The toxicity profile of systemic corticosteroids reflects the ubiquity of glucocorticoid receptor expression and the breadth of GR (glucocorticoid receptor)-driven transcriptional changes throughout the body. Adverse effects are dose-dependent and duration-dependent, with the risk of clinically significant toxicity increasing substantially above 5 mg/day of prednisone equivalent and with courses extending beyond 4 weeks. Understanding the mechanisms of each toxicity domain guides both prevention and management.
Metabolic and Endocrine Toxicity. Glucocorticoid (GC) excess drives a well-characterized metabolic syndrome that includes hyperglycemia, insulin resistance, dyslipidemia, and central adiposity. At the molecular level, GC transactivation of gluconeogenic enzymes (phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase) increases hepatic glucose output, while peripheral insulin resistance at the level of the glucose transporter type 4 (GLUT4) reduces glucose uptake in muscle and adipose tissue. The net effect is steroid-induced hyperglycemia, which may unmask latent type 2 diabetes mellitus (DM2) or worsen existing diabetes to the point of requiring insulin initiation. Fasting glucose measurements underestimate corticosteroid-induced hyperglycemia because the peak effect occurs postprandially, particularly in the afternoon and evening following morning doses. In patients without pre-existing diabetes, blood glucose monitoring after meals is more sensitive than fasting measurements. GC excess also causes central redistribution of adipose tissue (moon face, buffalo hump, truncal obesity), suppression of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) signaling, and in women at higher doses, suppression of gonadal axis function.1
Musculoskeletal Toxicity. Glucocorticoid-induced osteoporosis (GIOP) is the most clinically consequential long-term musculoskeletal adverse effect. GIOP occurs through two mechanisms: suppression of osteoblast-mediated bone formation (reduced OPG (osteoprotegerin), increased RANKL (receptor activator of NF-κB ligand), suppressed Wnt/beta-catenin signaling) and promotion of osteoclast-mediated bone resorption. The greatest rate of bone loss occurs in the first 3 to 6 months of therapy, making early bisphosphonate prophylaxis critical. American College of Rheumatology (ACR) guidelines recommend bisphosphonate prophylaxis for patients prescribed prednisone ≥2.5 mg/day for ≥3 months, with alendronate or risedronate as first-line oral agents. Calcium 1,000 to 1,500 mg/day and vitamin D 600 to 800 IU (International Units)/day are required in all patients on systemic corticosteroids. Avascular necrosis (AVN), also termed osteonecrosis, is a second distinct musculoskeletal complication: corticosteroids cause fat embolism and endothelial damage in subchondral bone blood vessels, leading to ischemic necrosis typically at the femoral head, humeral head, and femoral condyles. AVN can occur even after short high-dose courses (pulse methylprednisolone). Steroid myopathy is a third complication: proximal muscle weakness affecting hip flexors and shoulder girdle develops insidiously during long-term therapy; it is a diagnosis of exclusion distinguished from inflammatory myopathy by its non-inflammatory character (normal CK (creatine kinase), type II fiber atrophy on biopsy).1,2
Cardiovascular and Renal Toxicity. Systemic corticosteroids increase cardiovascular risk through multiple mechanisms: sodium retention and hypertension (via residual mineralocorticoid activity and direct vascular effects), dyslipidemia (elevated LDL (low-density lipoprotein) and triglycerides, reduced HDL (high-density lipoprotein)), endothelial dysfunction, direct effects on myocardial function, and acceleration of atherosclerosis through suppression of nitric oxide production and promotion of vascular smooth muscle proliferation. Even low-dose prednisone (5 to 10 mg/day) chronically administered substantially increases myocardial infarction (MI) and stroke risk in population studies. Blood pressure monitoring, lipid management, and cardiovascular risk factor optimization are essential components of long-term corticosteroid management. Renal toxicity is less prominent than with NSAIDs but occurs through fluid retention, hypertension-mediated glomerular damage, and in rare cases hypokalemic nephropathy from mineralocorticoid effects. Electrolyte monitoring (potassium, glucose, and in high-dose settings, magnesium) is appropriate at baseline and periodically thereafter.2
Ophthalmic Toxicity. Two distinct ophthalmic adverse effects are associated with systemic and topical corticosteroid use. Posterior subcapsular cataracts (PSC) form through direct GR-mediated effects on lens epithelial cells that promote abnormal differentiation and posterior migration; they are specifically associated with corticosteroids (not other drug classes) and are largely irreversible. PSC risk correlates with cumulative dose and duration rather than daily dose, meaning that annual screening is appropriate for patients on long-term therapy. Ocular hypertension and open-angle glaucoma develop through corticosteroid-induced trabecular meshwork dysfunction, reducing aqueous humor outflow and raising intraocular pressure (IOP). Topical ophthalmic corticosteroids carry the highest risk; systemic corticosteroids also raise IOP, with greater risk in individuals with a genetic predisposition to glaucoma. Patients with a family history of glaucoma or pre-existing elevated IOP require ophthalmologic monitoring. Intraocular pressure elevation is usually reversible on drug discontinuation, unlike PSC.3
Psychiatric and Neurological Toxicity. Psychiatric adverse effects of corticosteroids range from mild (insomnia, mood elevation, mild anxiety) to severe (frank psychosis, severe mania, major depression). The clinical spectrum is unpredictable: a patient who tolerated one course without psychiatric effects may develop psychosis on a subsequent course. Steroid psychosis typically presents within the first week of high-dose therapy (prednisone ≥40 mg/day or equivalent) and resolves within days to weeks of dose reduction or discontinuation. Euphoria and insomnia are common at moderate doses and often require no specific treatment beyond reassurance and adjustment of dosing timing (morning-only dosing reduces nocturnal insomnia). Major depression is more common than mania during tapering phases. In patients who develop severe psychiatric symptoms, dose reduction or discontinuation must be balanced against the severity of the underlying condition; antipsychotics and mood stabilizers may be required acutely. A prior history of psychiatric illness increases risk but does not absolutely contraindicate corticosteroid use; close monitoring is mandatory.3
Gastrointestinal, Dermatologic, and Growth Effects. Gastrointestinal (GI) adverse effects of corticosteroids alone are less prominent than those of NSAIDs, but the combination of corticosteroids with NSAIDs substantially increases peptic ulcer disease (PUD) risk (relative risk approximately 15-fold higher than either agent alone), making proton pump inhibitor (PPI) prophylaxis mandatory in patients receiving both drug classes. Corticosteroids alone are not routine indications for PPI prophylaxis unless additional GI risk factors are present. Dermatological effects include skin atrophy and striae from inhibition of fibroblast collagen synthesis, easy bruising and ecchymoses from capillary fragility, and impaired wound healing. Acne may occur at moderate to high doses due to androgenic stimulation. In children, growth suppression is a dose- and duration-dependent adverse effect mediated by suppression of GH and IGF-1 axis signaling and by direct effects on growth plate chondrocytes. Alternate-day dosing significantly attenuates growth suppression compared to daily therapy in pediatric patients requiring long-term systemic corticosteroids.1
Avascular necrosis (AVN) of the femoral head can follow even short high-dose corticosteroid courses (including pulse methylprednisolone) and may present months after treatment ends. Any patient who has received high-dose corticosteroids and develops hip, knee, or shoulder pain should be evaluated for AVN with MRI (the most sensitive modality, detecting AVN earlier than plain films). Plain radiographs are often normal in early AVN. Early diagnosis is essential because core decompression can preserve the joint if performed before structural collapse. There is no safe minimum dose below which AVN risk is zero; it is a class effect of corticosteroid therapy.
Immunosuppression from corticosteroids increases susceptibility to both opportunistic pathogens and reactivation of latent infections. Risk is cumulative, dose-dependent, and synergistic with other immunosuppressive therapies. The key clinical obligations are to quantify risk, screen for and treat latent infections before starting chronic therapy, provide appropriate prophylaxis, and employ steroid-sparing strategies to minimize the total corticosteroid exposure over time.
Dose Thresholds and Infection Risk. The concept of an immunosuppressive dose threshold is approximate but clinically useful. Prednisone <10 mg/day for <2 weeks is considered low-risk for opportunistic infections in otherwise immunocompetent patients. Prednisone ≥20 mg/day for ≥4 weeks substantially increases risk for bacterial, fungal, and opportunistic infections. Pulse corticosteroid therapy (e.g., methylprednisolone 1 g IV daily for 3 days) produces profound but transient immunosuppression and is associated with increased infection risk even without chronic exposure. Risk is markedly amplified when corticosteroids are combined with other immunosuppressants (calcineurin inhibitors, mycophenolate, azathioprine, biologics targeting TNF (tumor necrosis factor)-α or IL-6 (interleukin-6)). Commonly encountered serious infections in patients on systemic corticosteroids include Pneumocystis jirovecii pneumonia (PCP), invasive candidiasis, aspergillosis (particularly in severely immunosuppressed patients), bacterial pneumonia, urinary tract infections (UTI), and skin and soft tissue infections. Reactivation of latent tuberculosis (TB) and hepatitis B virus (HBV) are specific screens required before initiating chronic therapy.5
Pneumocystis jirovecii Pneumonia Prophylaxis. PCP (formerly called Pneumocystis carinii pneumonia) is caused by the opportunistic fungus Pneumocystis jirovecii and carries a mortality rate of 30 to 50% in immunosuppressed patients. Trimethoprim-sulfamethoxazole (TMP-SMX) 80/400 mg daily (single-strength) or 160/800 mg three times per week is the preferred prophylactic agent, with nearly 100% efficacy. Current evidence-based guidelines recommend PCP prophylaxis for patients receiving prednisone ≥20 mg/day (or equivalent) for ≥4 weeks in combination with other immunosuppressants, or for any patient receiving sustained corticosteroid therapy at doses producing a CD4⁺ (cluster of differentiation 4-positive) lymphocyte count below 200 cells per cubic millimeter (the threshold used for HIV-positive patients). In patients intolerant of TMP-SMX, alternatives include dapsone 100 mg/day, atovaquone 1,500 mg/day, or inhaled pentamidine 300 mg monthly. TMP-SMX also provides prophylaxis against toxoplasmosis and nocardiosis at the single-strength dose.4
Tuberculosis Screening and Management. Systemic corticosteroids at immunosuppressive doses can reactivate latent TB (LTBI), with prednisone ≥15 mg/day for ≥4 weeks representing the commonly applied threshold for pre-treatment screening. All patients about to begin prolonged moderate-to-high dose corticosteroid therapy should be screened with an IGRA (interferon-gamma release assay; QuantiFERON-TB Gold or T-SPOT.TB) or tuberculin skin test (TST), understanding that corticosteroid-induced immunosuppression may reduce the sensitivity of TST more than IGRA. Active TB must be ruled out clinically and radiologically. In patients with LTBI confirmed by IGRA or TST and no evidence of active disease, isoniazid (INH) preventive therapy for 9 months is initiated, ideally at least 4 weeks before starting immunosuppression in non-urgent cases. In urgent clinical situations (e.g., acute lupus nephritis), corticosteroids and INH can be started simultaneously.5
Hepatitis B Reactivation Screening. HBV reactivation in patients receiving systemic immunosuppression can cause severe acute hepatitis and liver failure. All patients initiating corticosteroid therapy at prednisone ≥10 mg/day for ≥4 weeks, or who will receive concurrent immunosuppressants, should be screened with hepatitis B surface antigen (HBsAg), antibody to hepatitis B core antigen (anti-HBc total), and antibody to hepatitis B surface antigen (anti-HBs). HBsAg-positive patients (chronic HBV infection) require antiviral prophylaxis with a high-barrier-to-resistance nucleotide analogue: entecavir 0.5 mg/day or tenofovir disoproxil fumarate (TDF) 300 mg/day or tenofovir alafenamide (TAF) 25 mg/day. Anti-HBc-positive but HBsAg-negative patients (past infection, occult HBV) have lower but non-zero reactivation risk; monitoring with HBV (hepatitis B virus) DNA (deoxyribonucleic acid) every 1 to 3 months is recommended; prophylaxis is indicated for those receiving high-level immunosuppression (e.g., anti-CD20 therapy combined with corticosteroids). HBV prophylaxis is continued for 6 to 12 months after cessation of immunosuppression.5
Live Vaccine Contraindication and Steroid-Sparing Strategies. Live attenuated vaccines (measles-mumps-rubella (MMR), varicella-zoster, yellow fever, intranasal influenza, live oral typhoid, oral polio, BCG (bacille Calmette-Guerin)) are contraindicated in patients receiving prednisone ≥20 mg/day for ≥2 weeks or equivalent immunosuppression, due to risk of vaccine-strain infection. Inactivated vaccines (injectable influenza, pneumococcal, recombinant zoster vaccine, Tdap) are safe and should be administered whenever feasible, ideally before immunosuppression begins. Steroid-sparing strategies are essential to limit cumulative corticosteroid exposure and toxicity. For rheumatic and autoimmune diseases, conventional disease-modifying antirheumatic drugs (DMARDs) such as methotrexate, hydroxychloroquine, leflunomide, and azathioprine provide background immunosuppression that allows corticosteroid tapering. For biologic indications, TNF-α inhibitors (etanercept, adalimumab, infliximab), IL-6 receptor antagonists (tocilizumab), and other biologics serve as corticosteroid-sparing agents. For asthma, long-acting beta-2 agonists (LABAs), long-acting muscarinic antagonists (LAMAs), anti-IgE (omalizumab), and anti-IL-5 agents (mepolizumab, reslizumab, benralizumab) reduce or eliminate the need for systemic corticosteroids.4,5
Before initiating prednisone ≥10 mg/day for anticipated duration ≥4 weeks: screen for LTBI (IGRA preferred), screen for HBV (HBsAg, anti-HBc, anti-HBs), update vaccinations (administer live vaccines at least 4 weeks before if possible; inactivated vaccines at any time), assess cardiovascular risk factors (BP, lipids, glucose), obtain baseline bone density (DEXA scan if anticipated duration >3 months), start calcium 1,000 to 1,500 mg/day and vitamin D, begin bisphosphonate if ≥2.5 mg/day for ≥3 months, consider PCP prophylaxis with TMP-SMX if ≥20 mg/day for ≥4 weeks with concurrent immunosuppression, counsel on sick day rules and emergency hydrocortisone.
Corticosteroid drug interactions fall into two mechanistic categories: pharmacokinetic interactions mediated primarily through CYP3A4 (altering corticosteroid plasma levels) and pharmacodynamic interactions (additive or antagonistic effects at target tissues). A third practical category is the live vaccine interaction, which is a safety rather than a pharmacokinetic issue. The corticosteroid withdrawal syndrome is a distinct clinical entity that must be differentiated from adrenal insufficiency because the two share overlapping features but have different thresholds and management implications.
CYP3A4 Pharmacokinetic Interactions. All systemic corticosteroids are substrates of CYP3A4, the dominant hepatic and intestinal wall metabolizing enzyme for this drug class. CYP3A4 inhibitors reduce corticosteroid clearance and raise plasma levels, potentially precipitating Cushing syndrome features even at doses not normally associated with toxicity. The most clinically hazardous inhibitor interaction is ritonavir (a component of many HIV (human immunodeficiency virus) antiretroviral regimens and boosting pharmacokinetics in other protease inhibitor combinations): ritonavir produces profound CYP3A4 inhibition that can raise fluticasone (inhaled) systemic exposure 350-fold, and triamcinolone (injected) exposure substantially, causing iatrogenic Cushing syndrome and secondary adrenal insufficiency at non-systemic corticosteroid doses. Azole antifungals (ketoconazole, itraconazole, voriconazole, posaconazole) are potent CYP3A4 inhibitors frequently co-prescribed with corticosteroids in immunosuppressed patients; this combination should be anticipated and corticosteroid doses adjusted if azoles are initiated. Diltiazem, verapamil, clarithromycin, erythromycin, and grapefruit juice are additional inhibitors with more modest effects. CYP3A4 inducers accelerate corticosteroid metabolism; rifampin is the most potent, reducing prednisolone area under the curve (AUC) by approximately 50 to 75% and potentially precipitating adrenal crisis in dependent patients when initiated without dose adjustment.6
Pharmacodynamic Drug Interactions. Several pharmacodynamic interactions with corticosteroids carry practical clinical significance. Corticosteroids combined with NSAIDs produce a multiplicative (approximately 15-fold) increase in peptic ulcer disease and GI (gastrointestinal) bleeding risk, requiring PPI (proton pump inhibitor) co-prescription. Corticosteroids antagonize the hypoglycemic effect of insulin and oral antidiabetic agents, necessitating intensification of diabetes management. Corticosteroids reduce the antihypertensive efficacy of diuretics, ACE (angiotensin-converting enzyme) inhibitors, and ARBs (angiotensin receptor blockers) through sodium retention and volume expansion; blood pressure management requires monitoring and dose adjustment. Corticosteroids combined with diuretics (particularly loop and thiazide diuretics) increase potassium wasting synergistically, raising risk of hypokalemia; potassium monitoring is required. Corticosteroids reduce the immunogenicity of vaccines administered during periods of immunosuppression, limiting the protection conferred by vaccination. Corticosteroids may increase the risk of tendon rupture in patients also receiving fluoroquinolone antibiotics, which themselves impair collagen synthesis; this combination should be used cautiously in patients with pre-existing tendinopathy.1
Corticosteroid Withdrawal Syndrome. The corticosteroid withdrawal syndrome is distinct from adrenal insufficiency and results from physiological dependence on supraphysiological glucocorticoid concentrations. Patients who have been maintained on pharmacological corticosteroid doses may develop a syndrome of arthralgia, myalgia, fatigue, headache, nausea, mood disturbance, and general malaise when doses are tapered, even when adrenal function has fully recovered and plasma cortisol levels are normal or supranormal. This syndrome occurs because tissues have adapted to chronically elevated glucocorticoid receptor activation and experience relative glucocorticoid deficiency when drug levels decline, even if those levels remain physiologically adequate. The clinical challenge is distinguishing withdrawal syndrome from: (1) adrenal insufficiency (managed by slowing the taper, not stopping it); and (2) relapse of the underlying inflammatory disease (managed by returning to a higher dose). Withdrawal syndrome is characterized by preserved adrenal function on ACTH (adrenocorticotropic hormone) stimulation testing and resolution within days to weeks with slower dose reduction, without the need for stress dosing or mineralocorticoid supplementation. Managing withdrawal syndrome requires patient education, reassurance, and a longer, more gradual taper, rather than dose escalation.7
Both present with fatigue, nausea, myalgia, and hypotension. Adrenal insufficiency (AI): morning cortisol low (<3 μg/dL); subnormal ACTH stimulation test; may have hyponatremia and hypoglycemia; requires slowing taper or stress dosing. Withdrawal syndrome: morning cortisol normal or elevated; normal ACTH stimulation; no electrolyte abnormalities; resolves with slower taper over longer time course. Relapse of underlying disease: inflammatory markers re-elevate; disease-specific symptoms recur; requires increase in immunosuppressive therapy, not just steroid dose adjustment. If any uncertainty, morning cortisol and ACTH stimulation testing are definitive.
Gout is the most common form of inflammatory arthritis in adults, caused by the deposition of monosodium urate (MSU) crystals in joints and periarticular tissues when serum urate concentrations persistently exceed the physiological solubility threshold of approximately 6.8 mg/dL (404 μmol/L). The acute gouty attack represents the clinical manifestation of the innate immune response to MSU crystals and is driven by a defined molecular pathway centered on the NLRP3 (NOD (nucleotide-binding oligomerization domain)-like receptor family pyrin domain-containing protein 3) inflammasome and interleukin-1 beta (IL-1β). Understanding this pathway explains both the acute attack and the pharmacological targets available for treatment.
Urate Metabolism and Crystal Deposition. Uric acid is the end product of purine catabolism in humans. Unlike most mammals, humans lack functional uricase (urate oxidase), the enzyme that converts uric acid to the more soluble allantoin, because the UOX (urate oxidase) gene was inactivated during primate evolution approximately 15 million years ago. As a result, serum urate concentrations in humans are 10-fold higher than in most other mammals, placing us at the upper limit of urate solubility. Renal urate handling involves glomerular filtration followed by extensive proximal tubular reabsorption (approximately 90%) mediated by the URAT1 (urate anion transporter 1, encoded by SLC22A12) and GLUT9 (glucose transporter 9, encoded by SLC2A9) transporters, with subsequent secretion and post-secretory reabsorption. Net renal urate excretion represents only about 10% of filtered load. Approximately two-thirds of daily urate production is excreted renally; one-third undergoes intestinal excretion. Hyperuricemia arises from urate overproduction (increased purine synthesis or cell turnover), decreased renal excretion (the most common cause in primary gout, affecting approximately 90% of patients), or both. Drug-induced hyperuricemia occurs with thiazide and loop diuretics (reduced renal excretion), low-dose aspirin, cyclosporine, niacin, pyrazinamide, and ethambutol.8
NLRP3 Inflammasome Activation and Acute Attack Pathogenesis. When serum urate exceeds 6.8 mg/dL, MSU crystals precipitate preferentially in cooler peripheral joints (first metatarsophalangeal joint, ankles, knees) where lower temperatures favor crystallization. Phagocytosis of MSU crystals by resident synovial macrophages and neutrophils triggers a sequence of innate immune responses. The key intracellular event is activation of the NLRP3 (NOD-like receptor family pyrin domain-containing protein 3) inflammasome, a multiprotein complex that assembles in response to cellular danger signals including urate crystals, mitochondrial reactive oxygen species (ROS), and potassium efflux. NLRP3 activation leads to autocleavage of procaspase-1 to active caspase-1, which in turn cleaves pro-interleukin-1 beta (pro-IL-1β) to the mature secreted form, IL-1β. Secreted IL-1β binds the IL-1 receptor (IL-1R) on synovial endothelial cells and fibroblasts, triggering a cytokine cascade including interleukin-6 (IL-6), interleukin-8 (IL-8, also CXCL8), and tumor necrosis factor-alpha (TNF-α) that drives neutrophil recruitment, endothelial activation, and the intense joint inflammation characteristic of an acute gout attack. The neutrophil influx amplifies the response: neutrophil crystal phagocytosis causes further NLRP3 activation and IL-1β release, creating a self-amplifying loop. The spontaneous resolution of acute attacks after 7 to 14 days even without treatment is believed to result from phagocyte apoptosis, lipid mediator (lipoxin A4) production, and exhaustion of the inflammatory cascade.89
NSAIDs for Acute Gout. NSAIDs are the first-line treatment for acute gouty attacks in the absence of contraindications (renal impairment, active peptic ulcer disease, anticoagulation, cardiovascular disease). Indomethacin has historically been the most-studied NSAID (non-steroidal anti-inflammatory drug) for gout and remains a standard reference agent at doses of 50 mg three times daily for 5 to 7 days, but is not superior in efficacy to other NSAIDs and is associated with higher rates of GI (gastrointestinal) and CNS (central nervous system) side effects (headache, dizziness, cognitive effects). Naproxen 500 mg twice daily and diclofenac 75 mg twice daily are equally effective and generally better tolerated alternatives. Full anti-inflammatory doses should be used and maintained for the full treatment course rather than tapering; early discontinuation is the most common cause of treatment failure. PPI (proton pump inhibitor) co-prescription is recommended for patients with GI risk factors. Celecoxib 400 mg loading dose followed by 200 mg twice daily is an evidence-based option for patients with GI intolerance to non-selective NSAIDs. NSAIDs are generally preferred over corticosteroids for acute gout when renal function allows, given their more favorable profile for short-course use.10
Colchicine for Acute Gout. Colchicine is a plant alkaloid derived from Colchicum autumnale (autumn crocus) with a mechanism of action distinct from NSAIDs: it binds tubulin and inhibits microtubule polymerization, impairing neutrophil chemotaxis, phagocytosis, and degranulation. Colchicine also inhibits the NLRP3 inflammasome by disrupting microtubule-dependent assembly and by reducing ASC (apoptosis-associated speck-like protein containing a CARD) oligomerization. Low-dose colchicine (1.2 mg immediately followed by 0.6 mg one hour later) is as effective as high-dose colchicine (historical regimens of 0.5 mg every hour to toxicity) and substantially less toxic. The GI tolerability of low-dose colchicine was established in the AGREE (Acute Gout Flare Receiving Colchicine Evaluation) trial. Colchicine must be initiated within 36 hours of acute attack onset for maximal efficacy; it is significantly less effective when started more than 36 to 48 hours after attack onset. Colchicine is renally cleared and dose reduction is required for estimated glomerular filtration rate (eGFR) <30 mL/min per 1.73 m²; it is contraindicated in severe renal failure (eGFR <15 mL/min per 1.73 m²) and hepatic failure. Critical drug interaction: colchicine is a CYP3A4 (cytochrome P450 3A4) and P-glycoprotein (P-gp) substrate; co-administration with potent CYP3A4 or P-gp inhibitors (clarithromycin, cyclosporine, ritonavir) raises colchicine plasma levels and can cause life-threatening toxicity (myopathy, neuromuscular toxicity, cytopenias).10
Corticosteroids and IL-1 Inhibitors for Acute Gout. Systemic corticosteroids are highly effective for acute gout and are the first-line treatment when NSAIDs and colchicine are contraindicated (severe renal impairment, anticoagulation, intolerance). Oral prednisone 30 to 40 mg/day for 5 days, then tapered over 7 to 10 days, produces rapid and complete resolution of acute attacks with an efficacy equivalent to indomethacin in randomized controlled trials. Intraarticular triamcinolone (40 mg for large joints, 20 mg for smaller joints) is effective for monoarticular attacks when systemic therapy is not preferred. A recognized hazard in practice is the rebound gout attack after corticosteroid taper; using a longer, more gradual taper (10 to 14 days rather than 5 days) and initiating urate-lowering therapy (ULT) only after the acute attack has fully resolved reduces this risk. IL-1 inhibitors provide targeted intervention at the critical cytokine mediator of gout inflammation. Anakinra (IL-1 receptor antagonist, 100 mg SC daily for 3 days) is used off-label for refractory acute gout and in polyarticular attacks where systemic options are contraindicated. Canakinumab (anti-IL-1β monoclonal antibody, 150 mg SC single dose) is approved in some jurisdictions for frequent refractory attacks; it produces prolonged (up to 16 weeks) attack suppression but carries significant cost and infection risk.9,10
Urate-lowering therapy (allopurinol, febuxostat, probenecid) should not be initiated during an acute gouty attack. Rapid changes in serum urate in either direction (reduction or increase) can mobilize urate crystals from tissue depots, triggering or prolonging attacks through a crystal shedding mechanism. The standard practice is to wait until the acute attack has fully resolved (typically 2 to 4 weeks) before starting or adjusting ULT. However, in patients already established on ULT who experience an attack, ULT should not be stopped, as fluctuating urate levels would worsen crystal instability.
Urate-lowering therapy (ULT) is the cornerstone of long-term gout management. Its goals are to dissolve existing urate crystal deposits, prevent new crystal formation, reduce attack frequency, and prevent chronic tophaceous gout and urate nephropathy. The decision to initiate ULT requires assessment of attack frequency, serum urate burden, presence of tophi, radiographic joint damage, and coexisting conditions that influence drug choice. A serum urate target of <6 mg/dL (360 μmol/L) is recommended for most patients; a target of <5 mg/dL (300 μmol/L) is recommended for patients with tophi, frequent attacks (≥3 per year), or evidence of urate-related joint damage.
Allopurinol -- Xanthine Oxidase Inhibition. Allopurinol is the most widely prescribed ULT and the first-line agent in most clinical guidelines. It is a structural analogue of hypoxanthine that inhibits xanthine oxidase (XO), the enzyme responsible for the final two steps of uric acid biosynthesis: conversion of hypoxanthine to xanthine and conversion of xanthine to uric acid. Allopurinol is itself metabolized by XO to its primary active metabolite, oxypurinol, which is a long-acting tight-binding inhibitor of XO with a plasma half-life of 18 to 30 hours, compared to allopurinol's own half-life of 1 to 2 hours. Oxypurinol is renally cleared; dose adjustment is mandatory in chronic kidney disease (CKD) to prevent oxypurinol accumulation, which is the principal cause of allopurinol hypersensitivity reactions. The starting dose is 50 to 100 mg/day, titrated upward by 100 mg increments every 2 to 4 weeks to achieve the serum urate target, with a maximum dose of 800 mg/day; doses above 300 mg/day are often required and are safe if titrated with renal function monitoring. HLA-B (human leukocyte antigen B) *5801 allele testing is recommended before starting allopurinol in patients of Han Chinese, Thai, Korean, and Vietnamese descent, as this allele confers approximately a 7% risk of severe cutaneous adverse reactions (SCAR) including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN).10
Febuxostat -- Non-Purine XO Inhibitor. Febuxostat is a non-purine selective inhibitor of xanthine oxidase that is structurally unrelated to allopurinol and does not require dose adjustment for mild-to-moderate CKD (eGFR ≥30 mL/min per 1.73 m²), making it useful in the subset of gout patients with renal insufficiency who cannot tolerate the required allopurinol dose reduction. Febuxostat is primarily hepatically metabolized (predominantly by glucuronidation and CYP1A2/2C8/2C9) and predominantly excreted via feces, with limited renal dependence. Standard doses are 40 mg/day or 80 mg/day. The CARES (Cardiovascular Safety of Febuxostat and Allopurinol in Patients with Gout and Cardiovascular Morbidities) trial found higher all-cause and cardiovascular mortality with febuxostat compared to allopurinol in patients with established cardiovascular disease, leading the FDA to add a safety communication that febuxostat should be reserved for patients who have failed allopurinol. The European FAST (Febuxostat vs. Allopurinol Streamlined Trial) trial did not replicate this mortality difference, and the pharmacological basis for the CARES finding remains debated; the current US guidance is to use allopurinol first-line and reserve febuxostat for allopurinol failure or intolerance.10
Uricosuric Agents -- Probenecid and Lesinurad. Uricosuric agents reduce serum urate by inhibiting the proximal tubular reabsorption transporters URAT1 (SLC22A12) and GLUT9 (SLC2A9), increasing renal urate excretion. Probenecid at 500 to 1,000 mg twice daily is the most widely available uricosuric and is effective as monotherapy in gout patients with normal renal function and without urolithiasis. Contraindications include CKD (eGFR <30 mL/min per 1.73 m², as efficacy requires adequate urine flow), urate overproduction (24-hour urinary uric acid >800 mg/day, increasing urolithiasis risk), and a history of urate nephrolithiasis. Low-dose aspirin (≤325 mg/day) blocks the uricosuric effect of probenecid and should be avoided if probenecid is used for gout; high-dose aspirin (≥3 g/day) paradoxically has uricosuric activity through a different transport mechanism. Probenecid interacts with numerous drugs (methotrexate, penicillins, cephalosporins, acyclovir, NSAIDs) by inhibiting their organic anion transporter (OAT)-mediated renal tubular secretion. Lesinurad is a selective URAT1 inhibitor that was available as combination therapy with allopurinol but was withdrawn from some markets due to limited commercial adoption despite regulatory approval; it remains listed in current guidelines as an option for add-on therapy in patients not meeting urate targets on XO inhibitors alone.11
Pegloticase -- Recombinant Uricase. Pegloticase is a pegylated recombinant porcine uricase that converts uric acid to allantoin, a highly soluble metabolite rapidly excreted by the kidneys. This mechanism is distinct from XO inhibitors and uricosurics in that it provides an enzymatic activity that humans lack, enabling dramatic reductions in serum urate (to near-zero levels acutely). Pegloticase is reserved for refractory tophaceous gout in patients who have failed or cannot tolerate conventional ULT. It is administered as a 8 mg IV infusion every 2 weeks. The principal limitations are immune-mediated. Approximately 40 to 50% of patients develop antibodies against pegloticase that accelerate drug clearance, abolish the hypouricemic effect, and dramatically increase the risk of anaphylaxis and serious infusion reactions. Loss of the serum urate response (serum urate rising above 6 mg/dL during treatment) predicts antibody formation and requires immediate drug discontinuation before the next infusion to avoid anaphylaxis. Co-administration of immunosuppression (most commonly methotrexate 15 mg/week started 4 weeks before pegloticase) substantially reduces anti-drug antibody formation and improves the proportion of patients who maintain response; this co-administration strategy is now endorsed in major guidelines.11
Gout Attack Prophylaxis During ULT Initiation. Initiation or dose escalation of any ULT reduces serum urate and can mobilize urate crystals from tissue depots, triggering acute attacks through crystal shedding. This paradoxical flare risk is highest during the first 6 months of ULT and is the primary reason patients discontinue therapy before reaching target urate levels. Guidelines recommend co-prescribing prophylactic low-dose colchicine 0.5 to 0.6 mg once or twice daily for the first 3 to 6 months of ULT initiation in all patients who can tolerate it, or low-dose NSAIDs as an alternative. If both colchicine and NSAIDs are contraindicated, low-dose corticosteroids (prednisone 5 to 10 mg/day) may be used as prophylaxis. Prophylaxis duration should extend for at least 6 months after achieving the serum urate target, and longer (up to 12 months) in patients with visible tophi. The target serum urate level for most patients is <6 mg/dL; for patients with tophi or frequent recurrent attacks, a target of <5 mg/dL accelerates crystal dissolution and reduces tophus volume more rapidly.10,11
Asymptomatic Hyperuricemia. Most patients with serum urate above the solubility threshold of 6.8 mg/dL will never develop clinical gout. The decision to treat asymptomatic hyperuricemia with ULT remains an area of clinical uncertainty and is not recommended in current major guidelines (ACR (American College of Rheumatology), EULAR (European Alliance of Associations for Rheumatology), BSR (British Society for Rheumatology)) as a routine practice, given the lack of evidence that ULT in asymptomatic patients reduces cardiovascular, renal, or metabolic outcomes in patients without gout. Exceptions where treatment of asymptomatic hyperuricemia may be considered include: serum urate ≥13 mg/dL in men or ≥10 mg/dL in women (very high levels at which nephropathy risk is substantial), patients receiving cytotoxic chemotherapy for malignancies with high tumor lysis risk (where allopurinol or rasburicase is standard prophylaxis), and patients with known urate nephropathy or recurrent urate nephrolithiasis regardless of gout history.11
Allopurinol hypersensitivity syndrome (AHS) is a severe, potentially fatal drug reaction characterized by fever, rash (ranging from maculopapular to SJS/TEN), hepatitis, eosinophilia, and renal failure. Risk factors include initiating at doses disproportionately high for the patient's renal function, high-dose diuretic use, and the HLA-B*5801 allele in Asian populations. Prevention: always start at 50 to 100 mg/day (not 300 mg/day as was historical practice), titrate slowly, and test for HLA-B*5801 in Han Chinese, Thai, Korean, and Vietnamese patients before prescribing. The starting dose should not exceed the patient's creatinine clearance (e.g., CrCl 30 mL/min → start at 50 mg/day, not 100 mg/day). Oxypurinol accumulation in renal impairment is the pharmacokinetic basis for increased hypersensitivity risk at higher doses in CKD.
Practical prescribing of corticosteroids and gout medications requires a structured approach to monitoring, prophylaxis, and dose management. This section consolidates the actionable clinical framework derived from the preceding sections, providing a monitoring schedule for long-term corticosteroid users and a summary algorithm for gout management from acute attack through maintenance urate-lowering therapy.
Monitoring Parameters for Long-Term Corticosteroid Use. Patients receiving systemic corticosteroids at prednisone ≥7.5 mg/day for ≥3 months require structured periodic monitoring. Blood pressure measurement at every visit identifies corticosteroid-induced hypertension early and guides antihypertensive management. Fasting blood glucose and hemoglobin A1c (HbA1c) should be checked at baseline and every 3 to 6 months; postprandial glucose monitoring is more sensitive than fasting measurements for detecting steroid-induced hyperglycemia during daytime corticosteroid dosing. Fasting lipid profile at baseline and annually guides lipid management. Dual-energy X-ray absorptiometry (DEXA) bone density scan at baseline and every 1 to 2 years assesses GIOP (glucocorticoid-induced osteoporosis) progression. Serum potassium and creatinine at baseline and periodically during therapy, particularly in patients also receiving diuretics or ACE (angiotensin-converting enzyme) inhibitors or ARBs (angiotensin receptor blockers). Ophthalmologic review annually for posterior subcapsular cataracts and intraocular pressure, particularly in patients with family history of glaucoma. In pediatric patients, growth velocity monitoring at every clinical visit and bone age assessment annually. Body weight and body composition changes (central adiposity, buffalo hump, moon face) should be assessed at each visit as markers of cumulative GC (glucocorticoid) exposure and Cushingoid progression.1,2
Gout Management Algorithm. Acute attack: treat promptly with first-line monotherapy (NSAID (non-steroidal anti-inflammatory drug) or colchicine 1.2 mg + 0.6 mg one hour later) if no contraindications; use corticosteroids or IL-1 (interleukin-1) inhibitors when first-line agents are contraindicated. Begin or continue intraarticular therapy for monoarticular attacks when systemic therapy is not ideal. Do not initiate or adjust ULT (urate-lowering therapy) during the acute attack. Interattack period: after full resolution (2 to 4 weeks), assess indications for ULT. Initiate ULT in patients with: ≥2 acute attacks per year, tophi on examination or imaging, radiographic joint damage, or CKD (stage 2 or worse). Start allopurinol at 50 to 100 mg/day (lower in CKD); titrate by 100 mg every 2 to 4 weeks to reach serum urate target. Check HLA-B (human leukocyte antigen B) *5801 allele status in at-risk populations before allopurinol. Co-prescribe colchicine 0.5 to 0.6 mg daily for 3 to 6 months as flare prophylaxis. Maintenance: monitor serum urate every 2 to 4 weeks during titration, then every 6 months once stable at target. If allopurinol fails to achieve target at maximum tolerated dose, consider febuxostat, add lesinurad, or refer to rheumatology. For refractory tophaceous gout failing conventional ULT, consider pegloticase with methotrexate co-administration.10,11
Chapter Summary -- Anti-Inflammatory Drug Pharmacology. This four-module chapter has covered the pharmacological foundations and clinical applications of the two dominant drug classes in anti-inflammatory pharmacology. Modules 1 and 2 addressed NSAIDs (non-steroidal anti-inflammatory drugs): their shared mechanism of COX (cyclooxygenase) inhibition, the pharmacological differences between non-selective and COX-2 (cyclooxygenase-2)-selective agents, and the systematic toxicity profiles encompassing GI (gastrointestinal) bleeding, cardiovascular risk, renal impairment, and aspirin-exacerbated respiratory disease. Modules 3 and 4 addressed corticosteroids: the molecular biology of glucocorticoid receptor signaling, the breadth of anti-inflammatory mechanisms that distinguishes corticosteroids from NSAIDs (including upstream PLA2 (phospholipase A2) inhibition, cytokine transrepression, and leukocyte trafficking effects), ADME (absorption, distribution, metabolism, and excretion) and the potency comparison table, clinical indications from emergency to chronic autoimmune disease, and the full toxicity, drug interaction, and prophylaxis profile. Module 4 also covered the pharmacology of gout, linking the NLRP3/IL-1β (interleukin-1 beta) pathogenesis of the acute attack to the mechanistically distinct drugs available for acute management (NSAIDs, colchicine, corticosteroids, IL-1 inhibitors) and for urate-lowering (allopurinol/xanthine oxidase inhibition, febuxostat, probenecid/URAT1 (urate anion transporter 1) blockade, and pegloticase/uricase replacement). Together these modules provide a complete pharmacological framework for managing the most prevalent inflammatory conditions encountered in clinical medicine.12
Acute attack: NSAIDs full dose ×5–7 days or colchicine 1.2 mg + 0.6 mg (if started ≤36 h) or prednisone 30–40 mg/day ×5 days (if contraindications to first-line). IL-1 inhibitors (anakinra, canakinumab) for refractory polyarticular disease. Do NOT start ULT during attack. After resolution (≥2–4 weeks): Start allopurinol 50–100 mg/day with colchicine 0.6 mg/day prophylaxis. Titrate allopurinol to serum urate <6 mg/dL (<5 mg/dL if tophi). Continue prophylaxis 3–6 months after target achieved. Allopurinol failure: Febuxostat (caution if CVD history) or add lesinurad. Refractory tophi: Pegloticase + methotrexate co-administration.
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