Antihistamines
PREGNANCY CATEGORY B OR C
Therapeutic Actions
Antihistamines competitively block the effects of histamine at peripheral H1 receptor sites, have anticholinergic (atropine-like) and antipruritic effects.
Indications
Relief of symptoms associated with perennial and seasonal allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis, mild, uncomplicated urticaria and angioedema
Amelioration of allergic reactions to blood or plasma
Treatment of dermatographism
Management of tremor in early parkinsonian syndrome and drug-induced extrapyramidal reactions
Control of nausea, vomiting, and dizziness from motion sickness (buclizine, cyclizine, diphenhydramine, meclizine)
Adjunctive therapy in anaphylactic reactions
Unlabeled uses: Relief of lower respiratory conditions, such as histamine-induced bronchoconstriction in asthmatics and exercise- and hyperventilation-induced bronchospasm
Contraindications and Cautions
Contraindicated with allergy to antihistamines, pregnancy, or lactation.
Use cautiously with narrow-angle glaucoma, stenosing peptic ulcer, symptomatic prostatic hypertrophy, asthmatic attack, bladder neck obstruction, pyloroduodenal obstruction.
Adverse Effects
CNS: Depression, nightmares, sedation
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