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Why Is My Cat’s Bottom Lip Swollen? 9 Vet Reviewed Reasons & What to Do

Written by: Chelsea Mortensen

Last Updated on January 24, 2024 by Catster Editorial Team

cat opening its mouth

Why Is My Cat’s Bottom Lip Swollen? 9 Vet Reviewed Reasons & What to Do


Dr. Lauren Demos (DVM) Photo


Dr. Lauren Demos (DVM)


The information is current and up-to-date in accordance with the latest veterinarian research.

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Your cat’s health is your responsibility—but sometimes you might not be sure whether anything is wrong. If you notice your cat has a swollen lip, should you be worried about it? Should you call an emergency vet? The truth is, there are many different causes of swollen lips. That can make it tricky to diagnose at home.

Luckily, it’s not a sign that you need to take emergency measures unless your cat is struggling to eat or breathe. Here are nine common reasons for lip swelling in cats.

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The 9 Reasons Why Your Cat’s Bottom Lip is Swollen

1. Food or Contact Allergy

One of the most common causes of swelling is an allergic reaction to something that touches your cat’s mouth. Your cat may have a food allergy that is causing a reaction. The most common allergies in cats are to specific meat proteins, such as chicken, beef, or pork. Consider switching food to see if your cat reacts better to a different brand and flavor of food.

Another possibility is an allergy to something else your cat regularly touches, such as a toy or food dish.

cat eating beef
Image Credit: liudmila_selyaninova, Shutterstock

2. Insect Bite or Sting

Another common cause of a swollen lip is due to a reaction to an insect bite or sting. Fleas, ticks, and mosquitos can all cause swollen bites anywhere, including the lips. Demodex mites are another insect that can cause swelling, hair loss, and other issues. In fact, the lack of fur around your cat’s lips might leave them especially vulnerable.

Cats can also get bee stings around their mouth if they try to bite or pick up a bee. Insect bites and stings usually will heal on their own, but if you see recurring bites, it’s possible your cat is flea-infested.

3. Toxin Exposure

Along with allergic reactions, your cat can also experience lip swelling from toxic reactions. This usually occurs when your cat eats something toxic to cats. One common culprit that often leads to swelling is the pothos plant—a beautiful and hardy houseplant with shiny, heart-shaped leaves that can come in a variety of green, yellow, and white patterns.

Look for other signs of poisoning, such as vomiting, bloody stools, diarrhea, and lethargy, to know if your cat is in serious danger.

pothos plant
Image Credit: sweetlouise, Pixabay

4. Tumor

Oral or skin cancer is somewhat rare in cats, but it is not unheard of. Small tumors can develop around your cat’s mouth and lips. A vet assessment is needed to diagnose the tumor and decide if it’s benign or cancerous. Tumors are much more common in elderly cats than young cats.

5. Dental Disease

Your cat might also be facing swelling due to any number of dental issues—a broken tooth, an abscess, or tooth rot are all possible culprits. If this is the case, you may see other signs of disease when you open your cat’s mouth, and your cat will probably show signs of pain. Depending on the issue, a small surgery or medication might be needed.

vet checking cats teeth
Image Credit: PRESSLAB, Shutterstock

6. Infection

Various types of infections can cause swelling around your cat’s bottom lip. This can include fungal infections such as ringworm or bacterial infections in a small cut or wound on your cat’s lip. Treatment generally involves antibiotics or antifungals to help kill the infection.

7. Immune System Disease

Pemphigus is an auto-immune disease that can affect your cat’s skin. It can cause swelling along with scabs, redness, and lesions anywhere on your cat’s skin, including the lower lip. It can be diagnosed with a skin biopsy. There are various treatment options available, but not all cats respond well to treatment.

orange cat with scabies
Image Credit: Suharji Esha, Shutterstock

8. Feline Acne

Feline acne often occurs in the hair follicles of the chin, causing pimples, swollen areas, and clogged pores. Treatment varies depending on the situation—sometimes a change of food dish and better cleaning is all that’s needed, but other cats need oral or topical medication. Usually, feline acne is a gross but ultimately minor problem.

9. Eosinophilic Granuloma Complex

Eosinophilic granuloma complex refers to a condition in which small swollen lumps called granulomas develop around your cat’s lips. Although this can sometimes be caused by allergies, at other times, the cause is unknown. Although we don’t always know what causes the eosinophilic granuloma complex, the good news is that it is generally easy to treat with anti-inflammatory drugs.

devon rex cat take medicine
Image Credit: Veera, Shutterstock


Last Thoughts

As you can see, there are so many different reasons that your cat might have swelling around its lips. Although you can rule some of these reasons out at home, it’s really best to take your cat to the vet and get a proper diagnosis, especially if the swelling is persistent or recurring. And, of course, if your cat is having difficulty eating or breathing, you should seek treatment right away.

Every cause has a different treatment, and finding the right way to help your cat can be tricky. Luckily, swollen lips are usually treatable.

Featured Image Credit: dimitrisvetsikas1969, Pixabay

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