A patient with haloperidol allergy reports neck stiffness and difficulty moving. What type of reaction should the nurse suspect?

• A. Akathisia
• B. Parkinsonism
• C. Synergistic
• D. Dystonia

Answer: (D)

Acute dystonia is the key idea here. It’s a sudden, painful, involuntary muscle contraction caused by dopamine D2 receptor blockade in the nigrostriatal pathway from antipsychotics like haloperidol. When these receptors are blocked, the balance shifts toward acetylcholine activity, leading to sustained muscle contractions that create abnormal postures. Neck involvement is common, producing torticollis and the kind of neck stiffness described.

This reaction typically appears soon after starting or increasing the dose of haloperidol, within hours to a few days, which fits the scenario you’re given. Treating it promptly with an anticholinergic such as benztropine or diphenhydramine usually relieves the spasms by rebalancing acetylcholine and dopamine. It’s also appropriate to assess haloperidol dosing or consider an alternative if needed.

To distinguish it from other EPS: akathisia presents as inner restlessness and an urge to move rather than twisting muscle contractions; parkinsonism features slower movements, tremor, and rigidity developing over days to weeks. The neck-spasm presentation aligns best with dystonia.