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Table 15 drug interactions involving antihistamines

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Table 15. Drug Interactions Involving AntihistaminesDrugEffectCimetidine, erythromycin, ketoconazoleIncreased loratadine plasma concentrationCNS depressants (alcohol, sedatives)Increased sedation (sedatingantihistamines)MAO inhibitors (phenelzine,tranylcypromine, isocarboxazid,furazolidone, procarbazine)Prolonged and intensified anticholinergicand CNS depressive effects (sedatingantihistamines)Decreased blood pressure(dexchlorpheniramine)PhenytoinDecreased phenytoin elimination(chlorpheniramine)Theophylline (doses >400 mg)Increased cetirizine plasma concentrationCNS = central nervous system; MAO = monoamine oxidase.
25OTC Advisor: Self-Care for Fever, Cough, Cold, and Allergywho are breastfeeding. No drug in-teractions with intranasal cromolynsodium have been reported.Sneezing is the most commonadverse effect reported for intranasalcromolyn. Other adverse effectsinclude nasal stinging and burning.Decongestants.Congestion is acommon symptom of allergic rhinitis.It usually can be controlled with sys-temic decongestants or short-termuse (no more than 5 days) of topicalnasal decongestants, as mono-therapy or in addition to antihistaminetherapy.Follow-UpMany patients achieve symptom-atic relief with initial nonprescriptiondrug therapy in 3 to 4 days, butcomplete relief of symptoms maytake 2 to 4 weeks. Patients who re-spond poorly to treatment shouldbe assessed to determine whetherthey are complying with allergenavoidance strategies and medicationregimens. Some patients may requirean increase in medication dosage ora switch to a different agent or formu-lation. Patients who do not respondto nonprescription therapy despitethese measures should be referred toa primary care provider.Patients who use ophthalmicantihistamines should consult an eyecare practitioner for symptoms thatdo not resolve within 72 hours.Points to RememberAllergic rhinitis is a systemic disease with prominent nasal symptoms. It is classifiedas mild intermittent, moderate/severe intermittent, mild persistent, or moderate/severepersistent, based on the duration and severity of symptoms.Allergic rhinitis is triggered by indoor and outdoor environmental allergens. Commonsymptoms include frequent paroxysmal sneezing; itching of the eyes, nose, and palate;anterior watery rhinorrhea; nasal congestion; and conjunctivitis (red, irritated eyes withprominent conjunctival blood vessels).Allergen avoidance is considered to be the best method of treating allergic rhinitis.However, many patients have no control over their work environment or are unable toimplement all of the recommended preventive measures at home.The goals of nonprescription medication therapy for allergic rhinitis are to reducesymptoms and improve the patient’s functional status and sense of well-being. Optionsinclude oral and ophthalmic antihistamines, topical and oral decongestants, and the mastcell stabilizer cromolyn sodium.

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Term
Fall
Professor
lee
Tags
Hyperthermia, fevers

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