What is the treatment for a dystonic reaction?

• A. Ketamine
• B. Diphenhydramine 50 mg IM/IV/IO
• C. Atropine
• D. Epinephrine

Answer: (B)

Dystonic reactions come from an imbalance in signaling in the basal ganglia caused by dopamine blockade, which leads to unwanted muscle contractions and abnormal postures. The treatment is an anticholinergic to rebalance the acetylcholine-dopamine interaction. Diphenhydramine is useful here because it provides a strong anticholinergic effect and can act rapidly in the central nervous system. Administering 50 mg intramuscularly, intravenously, or intraosseously delivers quick relief of the painful muscle spasms and abnormal movements characteristic of dystonia. The response is often seen within minutes, and the dose can be repeated if symptoms persist. Other drugs listed do not target this mechanism: ketamine is a sedative/anesthetic, atropine’s effect isn’t reliably therapeutic for dystonia, and epinephrine is for anaphylactic or shock-like states, not dystonic reactions.