Chlorphenamine is an H1-receptor antagonist that competetively blocks H1-receptor sites on tissues.

Oral, adult
Allergic conditions: 4 mg every 4-6 hr. Max: 24 mg daily.

Parenteral, adult
Adjunct in the emergency treatment of anaphylactic shock: 10-20 mg IM, SC, or slow IV inj over 1 min. Max dose: 40 mg daily.

Adverse drug reactions: CNS depression, sedation, drowsiness, lassitude, dizziness. GI upsets, anorexia or increased appetite, epigastric pain, blurring of vision, dysuria, dryness of mouth, tightness in chest, hypotension, muscular weakness, tinnitus, euphoria, headache, paradoxical CNS stimulation.

Adapted from CIMS Drug Information System. Internet. Accessed on January 10, 2016.