Certified Emergency Nurse (CEN) Practice Test

Diphenhydramine is an antihistamine that exerts its therapeutic effects primarily through its anticholinergic properties and its ability to cross the blood-brain barrier, where it can exert influence on the central nervous system (CNS). In the context of treating dystonic reactions, which may arise as a side effect of antipsychotic medications, diphenhydramine works by calming the CNS. This calming effect can counteract the heightened motor activity and abnormal muscle contractions characteristic of dystonia.

While it is true that diphenhydramine interacts with various neurotransmitter systems, its primary action in alleviating dystonic reactions in this scenario does not specifically involve reversing the effects of antipsychotics or directly blocking dopamine receptors. Instead, the calming mechanism helps to reduce the agitation and rigidity associated with dystonic reactions. This makes it effective in providing symptomatic relief for patients experiencing these types of movement disorders.