After receiving diphenhydramine,a patient complains that his mouth is very dry.This is not uncommon for patients taking this medication.Which drug effect is this patient experiencing?

A) Side effect
B) Adverse reaction
C) Toxic reaction
D) Supportive effect

Dry mouth is a side effect of diphenhydramine.Side effects are unintended,often predictable,physiological effects that are well tolerated by patients.Adverse reactions are harmful,unintended,usually unexpected reactions to a drug administered at a normal dosage.They are commonly more severe than are side effects.Toxic reactions are dangerous,damaging effects to an organ or tissue.Supportive effects are intended effects that support the integrity of body functions.