What should you know about Benadryl for cats?

Benadryl is a brand name commonly associated with diphenhydramine, an antihistamine. A veterinarian may consider an antihistamine for a specific problem, but a cat's cough, swelling, itching or breathing change can have several causes. Treating the visible symptom at home may delay care for the underlying illness.

Cats process medicines differently from people. Some human formulations contain extra ingredients, including decongestants or pain relievers, that can be dangerous for cats. Liquids may also contain sweeteners or alcohol. Never assume that a product labelled for children, a combination cold medicine, or a different strength is suitable.

Diphenhydramine can cause sleepiness, dry mouth, stomach upset, wobbliness or difficulty urinating. A cat may instead become unusually restless or agitated. The risk can be greater in cats with heart, eye, liver, kidney or urinary problems, or in cats already receiving sedating medicines.

Before giving anything, contact a veterinarian and provide your cat's weight, age, symptoms, existing conditions and current medicines. Read the active ingredients and strength from the package rather than relying on the brand name. Follow only the product and instructions supplied or confirmed by the veterinarian.

If your cat has already received Benadryl, keep the package and note the product, amount, time and route of administration. Do not induce vomiting or give another medicine unless a veterinary professional tells you to. Keep the cat somewhere quiet and observe alertness, coordination, urination and breathing.

Seek emergency veterinary care immediately for open-mouth breathing, marked effort to breathe, blue or grey gums, collapse, seizures, severe weakness, repeated vomiting, or rapidly developing swelling of the face or throat. These signs can threaten breathing and should not be managed with a home antihistamine.

Call a veterinarian promptly after a possible overdose or an unintended product exposure, even if your cat seems normal. Bring the packaging. A cough that persists, wheezing, poor appetite, fever, or reduced activity also needs assessment because respiratory disease, irritation and other conditions may require different treatment.

Ask what is causing the symptom, whether diphenhydramine is appropriate, which exact formulation is acceptable, and what changes should prompt an urgent visit. Also ask whether your cat's other medicines or medical conditions alter the choice of treatment.