H₁ antihistamines are effective for treating nasopharyngeal itching, sneezing,  watery rhinorrhea, and ocular itching, tearing, erythema.

•  Side effects associated with older H₁ antihistamines include sedation, visual disturbance, urinary retention, and arrhythmias

Newer H₁ antihistamines:( terfenadine (Seldane) astemizole (Hismanal))

• These agents exhibit less sedation associated with their reduced ability to cross the blood brain barrier.

• However, there are very important drug-drug interactions associated with this category.

  • For example, macrolide antibiotics such as erythromycin, clarithromycin (Biaxin), ketoconazole-class broad-spectrum antifungal drugs, inhibit  terfenadine (Seldane) or astemizole (Hismanal) metabolism.

  • Toxic levels of terfenadine (Seldane) or astemizole (Hismanal) may induce potentially fatal cardiac arrhythmias.

  • These new H₁ antihistamines are contraindicated for concurrent use with macrolide antibiotics and ketoconazole-class and fungal drugs or in the presence of impaired hepatic function or inpatients predisposed to arrhythmias.

Topical α-adrenergic agonists:

• Phenylephrine (Neo-Synephrine) or oxymetazoline (Afrin) reduce nasal congestion/obstruction.

  • Efficacy duration: limited due to rebound rhinitis and systemic effects which may include insomnia, irritability, and hypertension -- the latter which is seen more commonly with oral alpha adrenergic agonists.

 Oral α-adrenergic agonists may be useful in diminishing antihistamine-mediated sedation while improving antihistamine efficacy in relieving congestion. 

• However, there is a concern that these agents due to their potentially hypertensive effects, may precipitate adverse cardiovascular effects, such as stroke. 

• There has been an effort to remove such "pressor" agents from common over-the-counter cold medications.

 Cromolyn sodium: This agent is a liquid provided as a nasal metered-does spray.

• Cromolyn sodium (Intal) is not associated with side effects and typically is used prophylactically to reduce episodic allergen nasal mast cell activation. 

• This agent may be used as part of a anti-asthma drug regimen.

Intranasal glucocorticoids:

• Intranasal glucocorticoids are the most potent drugs available for management of established rhinitis (seasonal or perennial) and including vasomotor rhinitis

  • Topical-to-systemic activity greater for: flunisolide (AeroBid) or budesonide (Rhinocort), compared to beclomethasone (Banceril) or triamcinolone (Aristocort).

• Despite the different route of administration,  intranasal-administered glucocorticoids exhibit the same efficacy but with reduced systemic side effects compared to same agent administered orally.

• Side effects include local irritation, which is the most frequent side effect to Candida over-growth which is an unusual side effect

• Topical high potency glucocorticoids exhibit superior efficacy compared antihistamines during pollen season.

Immunotherapy (hyposensitization): This approach is based on repeated, subcutaneous injections of gradually increasing allergen (specific for the symptom complex) over a period of 3-5 years.

• Contraindications include significant cardiovascular disease and unstable angina

• Cautious use applies to patients receiving beta adrenergic blockers (due to difficulty in managing possible anaphylactoid responses to treatment)

• Clinical Management Sequence:

  1. Identification of allergens confirmed by allergens-specific IgE skin testing and/or serum assay.

  2. Avoidance of offending allergen

  3. Mild symptoms: prophylaxis with topical cromolyn sodium or single (bedtime) dose of  chlorpheniramine (Chlor-Trimeton) or astemizole (Hismanal) or terfenadine (Seldane) (decision based on side effects and presence of other concurrent medications or disease.

  4. Prominent symptoms: Topical beclomethasone (Banceril) or if needed budesonide (Rhinocort) or flunisolide (AeroBid)

  5. Management failure: immunotherapy