has atropine-like antiprutitic and sedative effects
P.O. 15 to 30 min 1 to 4 hr 4 to 7 hr
I.V. Immediate 1 to 4 hr 4 to 8 hr
I.M. 20-30 min 1 to 4 hr 4 to 8 hr
T1/2 : 2.5-7 hours Metabolized in Liver excreted in Urine
barbiturates, other CNS depressants: Possibly increased CNS depression
MAO inhibitors: Increased anticholinergic and CNS depressant effects of diphenhydramine
Alcohol can cause an increase in CNS depression
caution in renal or hepatic impairment (can alter the metabolism and excretion)
Keep elixir container tightly closed. Protect elixir and parenteral forms from light.
Expect to discontinue drug at least 72 hours before skin tests for allergies because drug may inhibit cutaneous histamine response, thus producing false-negative results.
Advise her to take drug with food to minimize GI distress.
Urge patient to avoid alcohol while taking diphenhydramine.
Instruct her to use sunscreen to prevent photosensitivity reactions.
Advise patient to avoid taking other OTC drugs that contain diphenhydramine to prevent additive effects.
ATI online Drug Guide