1.06 Dystonic Drug Reaction
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agk's Library of Common Simple Emergencies

Presentation
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Patients arrive with peculiar posturing or 
difficulty speaking, and are usually quite 
upset and worried that they are having a 
stroke. Often there is no history offered at 
all--the patient may not be able to speak, may 
not be aware he took any phenothiazines or 
butyrophenones (e.g., Haldol has been used to 
cut heroin), may not admit he takes psycho- 
tropic medication, or may not make the connect- 
ion between symptoms and drug (e.g., one dose 
of Compazine given for vomiting). Acute 
dystonias usually present with one or more of 
the following symptoms:

- buccolingual: protruding or pulling sensation 
   of tongue
- torticollic: twisted neck, or facial muscle 
   spasm
- oculogyric: roving or deviated gaze
- tortipelvic: abdominal rigidity and pain
- opisthotonic: spasm of the entire body

These acute dystonias can resemble partial 
seizures, the posturing of psychosis, or the 
spasms of tetanus, strychnine poisoning, or 
electrolyte imbalances. More chronic neurologic 
side effects of phenothiazines, including the 
restlessness of akathisia, tardive dyskinesias, 
and Parkinsonism, do not usually respond as 
dramatically to drug treatment as the acute 
dystonias.

What to do:
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- Give 2mg of benztropine (Cogentin) or 50mg of 
   diphenhydramine (Benadryl) iv, and watch for 
   improvement of the dystonia over the next 
   five minutes. This step is both therapeutic 
   and diagnostic. Benztropine produces fewer 
   side effects (mostly drowsiness), and may be 
   slightly more effective, but diphenhydramine 
   is more likely to be on hand in the ED.
- Instruct the patient to discontinue the 
   offending drug, and arrange for followup if 
   medications must be adjusted. If the culprit 
   is long-acting, prescribe benztropine 
   (Cogentin) 2mg or diphenhydramine (Benadryl) 
   25mg po q6h for 24 hours to prevent a 
   relapse.

What not to do:
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- Do not persist with treatment in the face of 
   a questionable response or no response, but 
   get on with the workup to find another 
   etiology for the dystonia (tetanus, 
   seizures, hypomagnesemia, hypocalcemia, 
   alkalosis, muscle disease, etc.).
- Do not use intravenous diazepam first, 
   because it relaxes spasms due to other 
   etiologies, and thus leaves the diagnosis 
   unclear.

Discussion
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The extrapyramidal motor system depends on 
excitatory cholinergic neurotransmitters and 
inhibitory dopaminergic neurotransmittors, the 
latter susceptible to blockage by phenothiazine 
and butyrophenone medications. Anticholinergic 
medications restore the excitatory-inhibitory 
balance. One intravenous dose of benztropine or 
diphenhydramine is relatively innocuous and 
rapidly diagnostic, and is probably justified 
as an initial step in any patient with a 
dystonic reaction.

References:
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- Lee AS: Treatment of drug-induced dystonic 
   reactions. *JACEP* 1979; 8:453-457.

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