They can be used prn, but adverse effects may limit their usefulness when taken on a daily basis.Some patients tolerate the adverse effects with prolonged use, but they may experience cognitive impairment, and driving skills may be affected.The second-generation antihistamines are nonsedating in most patients and are preferred as first-line therapy.
Induces also bronchial relaxation and increases heart rate and contractility by stimulating beta-adrenergic receptors.
Fexofenadine is a nonsedating second-generation medication with fewer adverse effects than first-generation medications.
The newer, second-generation (ie, nonsedating) antihistamines are usually preferable to avoid sedation and other adverse effects associated with the older, first-generation antihistamines.
Ocular antihistamine drops (for eye symptoms), intranasal antihistamine sprays, intranasal cromolyn, intranasal anticholinergic sprays, and short courses of oral corticosteroids (reserved for severe, acute episodes only) may also provide relief.
Cetirizine selectively inhibits histamine H1 receptor sites in blood vessels, GI tract, and respiratory tract, which in turn inhibits physiologic effects that histamine normally induces at H1 receptor sites. Bedtime dosing may be useful if sedation is a problem.
Pseudoephedrine stimulates vasoconstriction by directly activating alpha-adrenergic receptors of the respiratory mucosa.Long-acting tricyclic histamine antagonist selective for H1-receptor.Major metabolite of loratadine, which after ingestion is extensively metabolized to active metabolite 3-hydroxydesloratadine.Regular use of an intranasal steroid spray may be more appropriate for patients with chronic symptoms.Daily use of an antihistamine, decongestant, or both can be considered either instead of or in addition to nasal steroids.Selective leukotriene receptor antagonist that inhibits the cysteinyl leukotriene (Cys LT 1) receptor.