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Why is My Cat’s Bottom Lip Swollen?

Every day, we take for granted our God-given senses, and we do not give too much thought to these senses until we lose them. You can learn to live and adapt if you lose one of your senses.  On the other hand, cats use their senses to exist and navigate safely in this human world. All of a cat’s senses are extremely sensitive and necessary for its survival.

I bet not too many cat parents, including me, stopped to think about how sensitive a cat’s lips and mouth are for daily navigation. The lips of a cat are complex and complicated.

Who would have thought?

Why is My Cat’s Bottom Lip Swollen?

If you have not noticed it, cats are pretty closed-mouthed critters. It is challenging to look inside a cat’s mouth. The vet must manually open your cat’s mouth at the top and bottom to do an oral examination. Cats do not appreciate anyone messing with their mouth. This could be because the mouth is very sensitive.

If you notice the bottom lip of your cat being swollen, know that there may be several reasons why this is happening. It takes your vet’s expertise to determine if your cat has any oral issues. The vet will prescribe the proper treatment to take care of these issues.

A cat’s mouth contains hair, glands, sensitive skin, teeth, and tongue. So, if your cat develops a swollen bottom lip, you cannot help but notice this swelling. Even though several factors can cause the bottom lip of your cat to swell, allergies are the most common reason. The fancy name for this condition is an eosinophilic granuloma.

Eosinophils pertain to white blood cells. When a cat (or human) develops an inflammation, white blood cells rush to the affected area to attack the intruder. This causes swelling to occur in the area. Possible factors causing this swelling of the bottom lip are as follows.

  • Parasites
  • Auto-immune disease
  • Dental caries
  • Toxins

If you notice a swelling of your cat’s lower lip,

  • Investigate where the cat has been
  • Take note of your cat’s eating and drinking habits.

Your cat may or may display some of the following signs and symptoms.

  • Are there changes in your cat’s litter box routine?
  • Has your cat had new food, toys, or bedding since the symptoms?

Symptoms Associated with a Swollen Lip in Cats

Swelling generally occurs at the edge of the bottom lip. Lip inflammation in a cat can bring a host of signs and symptoms.

  • An ulcer or scab on the lip, much like a human who has a cold sore
  • Red gums
  • An oral tumor
  • Healing scabbed-over sores on the face or head that may present bleeding or oozing of clear, blood, or pus
  • Hair loss around the mouth
  • Itching throughout the body
  • Swollen chin
  • Noticeable bad breath
  • Excessive head shaking
  • Decreased eating, dropping of food, difficulty chewing
  • Excessive face rubbing
  • Drooling

Like humans, a cat has lymph nodes in the lower jaw and neck. If these are swollen, the cat likely has an oral infection somewhere.

Common Causes for a Cat’s Bottom Lip to Swell

Environmental Allergens

Since allergies are the most common issue causing lip swelling in a cat, you need to be aware of some more common things that can cause this allergy. However, as in humans, it is difficult to pinpoint a specific allergen. Most times, in humans and cats, the allergy symptoms are treated without knowing what caused the allergic reaction.

When you let your cat outside, they love to take their time to smell the roses (grass, weeds, trees, shrubs, and more). My cats even love to smell the aluminum on our doors and take their time in the doorways. Don’t ask me why. Allergic pollen is everywhere.

Food Allergies

Food is the number one culprit causing possible allergic reactions in cats. Did you change your cat’s food brand?

Food Dishes

When a cat eats, it is not uncommon for the cat to bump its lip on the dish, causing swelling in the lip.


Applying flea treatment to your cat year-round is vital because it is common for a flea to bite a cat’s lip, causing swelling.


A cat contracts parasites when it is bitten by mosquitos. The bite of a mosquito causes hypersensitivity in your cat.

  • Mites are parasites that burrow down and live under the cat’s skin and hair follicles. Sometimes these mites do not cause problems, even though they are spread among cats. Mites live in a cat’s head, ears, and lips and can infect the lips, causing swelling.


Located on these things and in the air is pollen. In the fall and spring seasons, you see more pollen. Cats are hypersensitive to pollen, the same as many people, which can cause their lips to swell.

Oral Tumors

Tumors can be benign or cancerous, so the vet may want a biopsy. Common tumors can be the same as those found in humans; squamous cell carcinoma, fibrosarcoma, or malignant melanoma. Skin cancers generally start around the mouth. The prognosis for these is poor and we always think of the worst-case scenario.

Dental Carries



Skin infections 

Skin infections present as bacterial infections and fungal infections such as ringworm can cause swollen lips.

Chin Acne

Like humans, cats develop plugged and inflamed hair follicles on the chin. These present like blackheads, causing lip swelling.


Cats can pick up toxins from house plants, such as but not limited to Pothos. If you have cats, eliminate inside plants or put your household plants where your cat cannot get to them.

What To Do If My Cat’s Bottom Lip Is Swollen? 

When allergies become a big problem for humans, they can go for skin testing to determine which of the more common allergens they are sensitive to. Cat parents cannot do this as there is no such test for a cat. However, you can watch your cat closely and try to determine what allergy exposure is affecting them. This is a real challenge; most times, the vet will treat the symptoms versus the cause.

Most times, humans or cats cannot pinpoint the cause unless the reaction is so severe that you know what caused the reaction. You can,

  • Do a food trial
  • Provide filtered water only
  • Change your cat’s food dishes

Some vets recommend changing food dishes. Researchers say that studies show more problems with plastic and stainless steel feeding dishes. They say that glass or ceramic dishes seem to cause fewer problems.

Be sure to wash your cat’s feeding dishes after they eat a meal. You wash your dishes each time you eat, right? Cats are no different. When your cat is done eating, wash its dish in hot soapy water and rinse well before its next meal.

Your vet may recommend the following. All of these tests cost money, but if the allergy is severe, you may want to consider doing them so the vet can appropriately treat your kitty.

  • Skin scrape
  • Fungal or bacterial culture
  • Skin biopsy
  • Blood tests
  • Medication trial and error

Never assume that your cat’s lip is swollen due to an allergen because there can be other more serious reasons, but also remember that a cat’s swollen lip is usually temporary, not a severe health concern, and is treatable. Practice caution when it comes to your fur baby. Let your vet examine your cat to rule out any other more severe health issues.