Diphenhydramine

Diphenhydramine

Species: Both

Antihistamine used for allergies, itching, mild allergic reactions, and motion sickness. Also used for mild sedation.

Caution in pets with glaucoma, prostate issues, heart disease, or high blood pressure. Avoid liquid formulations with **xylitol or alcohol**.

Common side effects: drowsiness, dry mouth, mild GI upset. Some pets (especially cats) may have paradoxical excitement.

Overdose causes extreme drowsiness, tremors, seizures, or hyperexcitability. In severe cases, respiratory failure is possible. Treat with IV fluids, seizure control.

Store tablets at 59–86°F in a dry place. Keep liquid formulations refrigerated if instructed. Avoid human formulations with toxic additives.