Diphenhydramine and Pets
Find out if Diphenhydramine is toxic to dogs and cats.
Think your pet ate something toxic?
Call ASPCA Animal Poison Control Center: (888) 426-4435 or view emergency guide
Diphenhydramine—commonly known by the brand name Benadryl—is an over-the-counter antihistamine used in humans to treat allergies, itching, motion sickness, and insomnia. While veterinarians may sometimes recommend it for dogs, it can be dangerous or even life-threatening if the wrong dose is given, the wrong product is used, or the pet has underlying health conditions. Cats are particularly sensitive, so never give diphenhydramine to a cat without explicit veterinary guidance.
Pets can be exposed by eating tablets, capsules, or liquid drops left within reach, or by being given a human dose intended for an adult. Many diphenhydramine products are also combined with other drugs, such as acetaminophen, pseudoephedrine, or xylitol-sweetened liquids, which can cause additional and severe poisoning in dogs and cats. Even “plain” diphenhydramine can cause sedation, dry mouth, vomiting, rapid heartbeat, agitation, or urinary retention when overdosed.
To keep your pet safe, store all medications in a secure cabinet and never assume a human medication is safe for animals. If you think your pet has ingested diphenhydramine, contact your veterinarian or a pet poison control center right away. Bring the medication packaging to help the veterinary team identify the exact strength and ingredients.
Is Diphenhydramine Toxic to Dogs?
Veterinary use is possible under professional guidance, but overdose or inappropriate dosing can cause sedation, dry mouth, urinary retention, and more serious effects. Combination products containing acetaminophen, pseudoephedrine, or xylitol are especially dangerous.
Is Diphenhydramine Toxic to Cats?
Cats are more sensitive than dogs; incorrect dosing can cause severe sedation, agitation, abnormal heart rhythms, or life-threatening complications. Never give a cat diphenhydramine without veterinary advice.
Active Ingredients
- Diphenhydramine hydrochloride
- Diphenhydramine citrate
Common Brand Names
- Benadryl
- ZzzQuil
- Sominex
- Nytol
- Unisom SleepGels
- Tylenol PM
Dosage Form
tabletscapsulesliquidtopical cream or spray
Common Uses
- Allergies and itching
- Motion sickness
- Insomnia
- Cold and flu symptoms
Toxic Ingredients
- Diphenhydramine (in overdose)
- Acetaminophen (in combination products)
- Pseudoephedrine (in combination products)
- Xylitol (in some liquid formulations)
Symptoms to Watch For
- sedation
- lethargy
- dry mouth
- vomiting
- diarrhea
- urinary retention
- rapid heartbeat
- agitation or hyperactivity
- dilated pupils
- ataxia
- respiratory depression
- seizures
What If My Pet Was Exposed to Diphenhydramine?
Contact your veterinarian or a pet poison control center immediately if your pet may have ingested diphenhydramine. Do not induce vomiting unless instructed. Bring the product packaging so the exact formulation and strength can be identified.
Sources
Vet's Note
PetPilot provides general information for educational purposes. While we reference authoritative veterinary organizations, this page has not been individually reviewed by a veterinarian for your specific pet. Individual animals may react differently based on age, weight, breed, health conditions, and amount consumed. Always consult your veterinarian or a poison control center for personalized advice, especially if your pet is ill, injured, pregnant, nursing, or on medication.