What Are the Side Effects of Benadryl in Cats?

Benadryl is the brand name for the drug diphenhydramine. This drug is an antihistamine that treats allergies in both pets and humans. Use veterinarian dosing and supervision when administering Benadryl to cats or any pets. Allergy symptoms such as itchy skin, watering eyes and runny noses are often relieved in cats with the use of Benadryl.
  1. Drooling

    • Benadryl tastes tart to cats. Some cats begin immediate drooling from the taste of oral Benadryl. Try disguising the flavor in a small amount of seafood-flavored canned cat food. This can reduce the amount of drooling.

    Fatigue

    • Another side effect of Benadryl in cats is fatigue. Cats tend to take more frequent and longer naps. Keep an eye on the cat to be certain that it is waking at intervals. The cat might not be as playful as it was prior to the medication.

    Vomiting

    • Keep an eye on the cat for vomiting from the use of Benadryl. Vomiting can cause dehydration due to loss of fluids. Be certain cats have access to clean, fresh water at all times when administering Benadryl. Notify your veterinarian if vomiting occurs.

    Diarrhea

    • Another important reason for plenty of water is the side effect of diarrhea. Dehydration is always a risk to any animal suffering from diarrhea. If the diarrhea last more than 24 hours, be certain to notify the veterinarian.

    Appetite Loss

    • Do not expect cats to eat as much when on Benadryl. Monitor how much food the cat eats. Keep an eye on the cat's weight. Tempt the cat to eat more food by giving it its favorite foods and offering nutritious canned food. Limit treats if the cat is not eating regular amounts. Noticeable weight loss should be reported to the veterinarian supervising the Benadryl usage.

    Cotton Mouth

    • Tempt cats to drink more frequently by adding water to their food. Cotton mouth or dry mouth is a potential side effect of Benadryl. Moisten the cat's lips periodically with a few drops of clean water to help relieve symptoms of dry mouth.