Second-generation oral antihistamines (loratadine, desloratadine(Drug information on desloratadine), fexofenadine, cetirizine, levocetirizine(Drug information on levocetirizine)) are effective for pruritus and rhinorrhea in allergic rhinitis, although they are less effective for nasal congestion and are of no proven use in nonallergic rhinitis.7 They can be used as needed for rhinitis symptoms, but they generally are more effective with continuous use.8 As a group, the second-generation agents have fewer side effects than first-generation agents (diphenhydramine, chlorpheniramine, hydroxyzine, and others), which can cause sedation and anticholinergic side effects.9
In a double-blind study, the performance in a driving simulator of participants who took 50 mg of diphenhydramine(Drug information on diphenhydramine) was similar to or worse than that of persons with a blood alcohol(Drug information on alcohol) concentration of 0.1%, whereas the performance of participants who took 60 mg of fexofenadine(Drug information on fexofenadine) was not significantly different from that of those who received placebo.10 First-generation antihistamines have also been associated with impaired learning and school performance in children.
Among the second-generation oral agents, loratadine(Drug information on loratadine) and desloratadine generally have somewhat less efficacy11-13 and slower onset of action11-14 than other agents. The intranasal antihistamines (azelastine, olopatadine(Drug information on olopatadine)) have rapid onset of action15 and may be more effective than oral antihistamines,16,17 but combining agents from the 2 classes may not be better than using the intranasal antihistamine by itself.17 Unlike oral antihistamines, intranasal antihistamines have proven utility for vasomotor rhinitis.18 The principal adverse effects of intranasal antihistamines include bad taste and somnolence.18
Intranasal decongestants, such as oxymetazoline(Drug information on oxymetazoline), cause vasoconstriction and decrease nasal congestion, although they do not substantially affect itching, sneezing, and rhinorrhea.1 They can be useful in the short term in severely congested patients to allow other agents (eg, nasal corticosteroids or nasal antihistamines) to reach their site of action. While there is some evidence that intranasal decongestants can be safely tolerated for weeks,19 rebound congestion (rhinitis medicamentosa) may begin to develop within 3 days.20 Generally speaking, intranasal decongestants should not be recommended for longer than 3 days of continuous use.
Oral decongestants, such as pseudoephedrine(Drug information on pseudoephedrine) and phenylephrine(Drug information on phenylephrine), are α-agonists and work similarly to topical agents. They alleviate congestion caused by both allergic and nonallergic rhinitis. Although they do not cause rhinitis medicamentosa, they have the potential for systemic adverse effects, including palpitations, irritability, and elevated blood pressure.1 However, the effect on blood pressure is probably overestimated: in a well-done meta-analysis, pseudoephedrine raised systolic blood pressure by an average of 1 mm Hg, increased pulse by 3 beats per minute, and did not affect diastolic blood pressure.21 Because of significant individual patient variability in these parameters, close monitoring remains important.
An intranasal preparation of the anticholinergic drug ipratropium is useful for the treatment of rhinorrhea in both allergic22 and nonallergic rhinitis23-25 as well as in rhinitis caused by the common cold.26
The efficacy of the leukotriene receptor antagonist montelukast(Drug information on montelukast) in the treatment of allergic rhinitis is similar to that of oral antihistamines, and select studies suggest an additive benefit in combination with oral antihistamines. However, this combination is less effective than singleagent use of an intranasal corticosteroid for most patients.27 Montelukast is also useful in the treatment of asthma.28
Cromolyn, a mast cell stabilizer available as a nasal spray or eyedrops, is effective in preventing allergic rhinitis symptoms before allergen exposure. However, given a 4 times daily dosing regimen and limited efficacy following symptom onset, topical cromolyn preparations are of modest practical value for most patients.