Diphenhydramine

Diphenhydramine: Uses, Dosage and Side Effects

Overview

• Antihistaminergic (H1) effects are utilized to alleviate pruritus and prevent motion nausea.
• Additionally, it is a moderate anxiolytic and sedative.

Uses of Diphenhydramine

• To control mild pruritus (cats, dogs).
• Prevent motion sickness in dogs.

Dose of Diphenhydramine in Dogs and Cats

Dogs:

• Antiemesis: 2–4 mg/kg p.o. q6–8h.
• Suppression of pruritus: 1–2 mg/kg p.o. q8–12h.

Cats:

• 2–4 mg/kg p.o. q6-8h, 1 mg/kg i.v., i.m. q8h

Side Effects of Diphenhydramine in Dogs and Cats

• Paradoxical excitement may be seen in cats.

Contraindications of Diphenhydramine in Dogs and Cats

• Urine retention, glaucoma, and hyperthyroidism

Some Notes:

• An increased sedative effect may occur if used with benzodiazepines or other anxiolytics/hypnotics.
• Avoid the concomitant use of other sedative agents.
• Diphenhydramine may enhance the effect of adrenaline and partially counteract
  the anticoagulant effects of heparin