Benadryl For Cats – Uses, Dosage and Side Effects




Benadryl uses   Benadryl dosage for cats   Precautions and side effects   How is Benadryl supplied?

Benadryl (dipenhydramine) for cats

Benadryl uses:




Benadryl (active ingredient diphenhydramine hydrochloride) is an over the counter antihistamine used to treat allergies in people. It is also a recognised medication for cats and dogs to help with allergies, insect bites and stings, rashes (urticaria), irritations, motion sickness and nasal congestion.

The medication works by blocking the effects of histamine, a compound released by cells which caused many of the symptoms of allergies such as a runny nose and itchy skin.

Benadryl dosage for cats:

Dosage seems to vary depending on the source. The Veterinary Drug Handbook by Donald C. Plumb recommends 2 mg/kg. Merck recommends 2-4 mg/kg, the general consensus seems to be:

1 milligram (mg) per pound, or 2 mg per kilo, twice a day.

See charts below.

Kilos Dosage
3 kilos 6 mg
3.5 kilos 7 mg
4 kilos 8 mg
4.5 kilos 9 mg
5 kilos 10 mg
5.5 kilos 11 mg
6 kilos 12 mg
Pounds Dosage
6 lbs 6 mg
7 lbs 7 mg
8 lbs 8 mg
9 lbs 9 mg
10 lbs 10 mg
11 lbs 11 mg
12 lbs 12 mg

Always check with your veterinarian before giving any medications to your cat and check the packaging to determine the strength of the medication.

There is no specific cat Benadryl, the medication for cats is the same as the medication for people and is available from any chemist. There may be generic versions of Benadryl (which is a registered trademark of Johnson and Johnson). Make sure the only active ingredient is diphenhydramine hydrochloride. Some preparations may also contain more than one active ingredient which can lead to serious poisoning in cats.

Precautions and side effects:

Any medication can have side effects, and these may include:

  • Urinary retention.
  • Drowsiness.
  • Foaming at the mouth (due to the bitter taste).
  • Vomiting.
  • Diarrhea.

Do not give Benadryl to cats who are allergic to diphenhydramine hydrochloride.




Benadryl should not be used in cats suffering from the following conditions:

  • Glaucoma.
  • Liver disease.
  • Kidney disease.
  • Heart disease.
  • Hyperthyroidism.
  • High blood pressure.

Check with your veterinarian before medicating a pregnant or lactating cat.

How is Benadryl supplied?

Benadryl comes in tablet, oral liquid or injectable form.

Oral tablets: 12.5 mg, 25 mg, 50 mg.

Oral liquid: 12.5 mg per 5ml.

Injectible: 50 mg per millilitre.

Also see:

Cat antibiotics  




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