Cat Foaming At The Mouth After Medication

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  • Why is my cat foaming at the mouth after receiving oral medication?

    Some medications can cause the cat to drool or foam at the mouth after administration, which is medically known as drug-induced sialorrhea or hypersalivation.

    Hypersalivation occurs due to the bitter taste of certain medications, which can increase saliva flow as a way to clear the taste from the mouth. It tends to look more dramatic than it is. Common types of medications that can trigger foaming at the mouth include diphenhydramine (Benadryl), metronidazole (Flagyl) and sulfa antibiotics.

    Topical flea products can also result in hypersalivation if the cat accidentally licks the product. While it is generally harmless if the cat licks a cat topical product, contact with a dog flea treatment is a different and more dangerous situation. Cats are not small dogs and they are unable to process many medications including pyrethrin and permethrin which are common ingredients in dog flea treatments.


    No medical treatment is necessary for hypersalivation due to veterinary prescribed oral medications unless the cat is displaying additional symptoms. It can help to offer the cat something tasty to eat or drink such as tuna juice or milk (preferably lactose-free, but ordinary milk will do at a pinch).

    Cats are smarter than we think and most will turn their nose up at food with crushed up medications. Hiding medication in pill pockets (soft mouldable treats) or a cube of cheese may work, but not always.

    Speak to your veterinarian about the possibility of compounding or transdermal medications. Compounding takes the medication reformulates them into flavoured liquids or chews, which are more appealing to cats. Transdermal medications are drugs dissolved into a gel and applied to the skin of the pinna (ear).


    Only administer medications that have been prescribed by a veterinarian. While some medications can cause hypersalivation, non-prescribed drugs can be potentially life-threatening.

    When to see a veterinarian

    Always seek the advice of a veterinarian if your cat is drooling and has not been medicated recently. There are a number of possible causes of drooling.

    • Poisoning
    • Dental problems
    • Ingestion of plants that contain insoluble calcium oxalate crystals
    • Nausea
    • Pain
    • Foreign object in the mouth
    • Topical flea products
    • Oral tumours
    • Kitten teething
    • Liver disease
    • Reflux
    • Rabies
    • Pseudorabies


    • Julia Wilson, 'Cat World' Founder

      Julia Wilson is the founder of Cat-World, and has researched and written over 1,000 articles about cats. She is a cat expert with over 20 years of experience writing about a wide range of cat topics, with a special interest in cat health, welfare and preventative care. Julia lives in Sydney with her family, four cats and two dogs. Full author bio