Worried about diphenhydramine, what are its side effects.

Dear Ask The Doctor: Are there any serious health risks from long-term use of diphenhydramine?

Dear Dona: Diphenhydramine in the short term may cause drowsiness, dry mouth, increased heart rate, nausea and vomiting. Long term usage may cause confusion, impaired movements, blurring of vision and short term memory loss. Please consult your doctor if you experience any of the above mentioned side effects.