It is a human medicine. A vet may still prescribe it for a dog or cat, which is legal and common, but it means no company has proved to the FDA that it works or is safe in that animal, and there is no approved animal dose to look up. Ask your vet what they expect it to do and what to watch for.
The label says, word for word:
Human Drug Facts label, Uses: "temporarily relieves these symptoms due to hay fever or other upper respiratory allergies: runny nose, sneezing, itchy, watery eyes, itching of the nose or throat" and "temporarily relieves these symptoms due to the common cold: runny nose, sneezing". There is no FDA-approved animal label for diphenhydramine.
Drug Facts "Do not use": to make a child sleepy; with any other product containing diphenhydramine, even one used on skin.
Ask a doctor before use if you have a breathing problem such as emphysema or chronic bronchitis, glaucoma, trouble urinating due to an enlarged prostate gland.
Ask a doctor or pharmacist before use if you are taking sedatives or tranquilizers.
When using this product marked drowsiness may occur, avoid alcoholic drinks, alcohol, sedatives, and tranquilizers may increase drowsiness, be careful when driving a motor vehicle or operating machinery, excitability may occur, especially in children.
If pregnant or breast-feeding, ask a health professional before use.
Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center right away. (1-800-222-1222)
Diphenhydramine (Benadryl) is a human over-the-counter drug; the DailyMed label category is "HUMAN OTC DRUG LABEL", marketing category "OTC Monograph Drug" (monograph citation "M012"), active ingredient "Diphenhydramine HCl", purpose "Antihistamine". The label mentions no animals or pets, and no FDA-approved animal drug containing diphenhydramine was found on DailyMed or fda.gov in this research. Veterinarians may use it extra-label under AMDUCA.
The emergency page sorts the signs by how long you have, and the symptom checker asks what you are seeing. Reactions to a medicine can also be reported to the FDA yourself: how to report a problem.
These answers come from the label on DailyMed, read on 2 October 2026. Where the label does not say, the answer says so, and the vet or the pharmacist is the one to ask.
What the label says it is for is quoted at the top of this page. The label read for these answers is the one for Benadryl Allergy Ultratabs, a human tablet sold over the counter: it is an antihistamine for hay fever, allergy and common cold symptoms in people and does not mention dogs or cats, so ask the vet whether it is right for your pet.
The label gives no time. Ask the vet what to expect and by when.
The label gives directions for people only, by age, so the amount and the timing for your pet come from the vet. It does not say whether to take the tablets with food. The tablets on this label have one active ingredient, diphenhydramine, and the label says not to use them with any other product that contains diphenhydramine, even one used on the skin. Show the vet or the pharmacist the exact box you have.
The label does not say what to do about a missed dose. Call the clinic or the pharmacy before you give the next one.
The warnings on the label are quoted above. This label is written for people. It says marked drowsiness may occur, and that excitability may occur, especially in children. The label has nothing on dogs or cats, so ask the vet what to watch for and when to call.
The label says to store the tablets between 68° and 77°F and to protect them from light. It says not to use a tablet if its blister unit is torn or broken. Keep it out of the reach of children.
The FDA says the best way to get rid of most unused or expired medicines is a take-back option: a drug take-back location, which can be at a pharmacy or a police station, or a prepaid mail-back envelope. If you cannot use one and the medicine is not on the FDA's flush list, the FDA says to mix it, uncrushed, with something unappealing such as dirt, cat litter or used coffee grounds and to seal the mixture in a plastic bag before throwing it away. Flushing is only for medicines on that list, such as opioids. Do not give leftovers to another pet.
Write the dose, the times and the stop date here, then print this page for the fridge.
Dose and times: _____________________________________________
Stop date: _____________________________________________