Which therapeutic outcome should a nurse expect when administering diphenhydramine to a client with Parkinson's disease?

When administering diphenhydramine to a client with Parkinson's disease, the expected therapeutic outcome is a reduction in tremors. Diphenhydramine, an antihistamine with anticholinergic properties, can help alleviate tremors, which are a common and debilitating symptom in individuals with Parkinson's disease. This medication acts on the neurotransmitter systems that involve acetylcholine, which is often imbalanced in Parkinson's patients due to the degeneration of dopaminergic neurons.

While symptoms like muscle rigidity and balance issues can also be present in Parkinson's disease, the focus of diphenhydramine’s specific action is more directly related to tremors than to these other symptoms. Improved sleep is a potential benefit of diphenhydramine due to its sedative effects, but the primary and more direct outcome related to the symptomatology of Parkinson's is its effect on reducing tremors.