Why Does Your Cat Have A Swollen Lip?

For the most apprehensive of us, any changes in our pets can easily make us worried.

Any sign of sickness, be it behavioral or physical like a swollen lip, shouldn’t be underestimated, although it’s not always critical.

When a cat has a swollen lip, there may be many causes, including their diet, environment, dental issues.

It’s not always a concerning sign, but if the problem doesn’t go away in a few days or it’s recurring, it might be hiding a bigger issue.

Why Does Your Cat’s Lip is Swollen?

The reason for a cat’s swollen lip is often eosinophilic granuloma complex or EGC.

This term is used to describe a group of skin disorders, and often when this condition is present your cat’s bottom lip will be swollen.

EGC can have many causes, including a wrong diet, bugs, dental or environmental issues, but it’s commonly caused by an allergy.

Listed below are a few common causes of EGC along with other possible conditions behind cats’ swollen lower lip.

Food Allergy 

Have you recently changed the type or brand of food you give to your cat? That could be the reason why your cat has a fat lip.

Just like us, cats can be allergic to food, and some of these allergies can be very dangerous or hide more serious conditions, like onion poisoning.

Many brands of dry and wet food have industrial additives to make food more appetizing to your pet. Some of these components may ignite an allergic reaction in your pet.

Sometimes simply removing the problematic food solves the problem. Other times, even if the cause is found, the swollen lip on the cat remains.

In this case, you can keep your cat on a hypo-allergenic diet for a while, and see if the problem solves itself. Topical medication may be needed to help the healing process.

Of course, you should consult your veterinarian before changing your cat’s diet or giving them medications.

If your cat suffers from recurring episodes of swelling, keeping your pet on a hypo-allergenic diet for the rest of their life could be a solution.

Bug Bites 

When the season is warm and mosquitos are out for our blood, it’s not uncommon to see a cat with a swollen lip.

Mosquito bites are the most common cause of EGC during summer, but it’s not always easy to know for sure that your cat fat lip was provoked by a mosquito, so if it doesn’t go away in the span of a few days, call your veterinarian.

Mosquitoes aren’t the only culprits behind a swollen lip in cats. During summer, as well as the rest of the year, it’s not uncommon for bugs and insects to come into our home.

Surely if you have an outdoor cat, you have to consider the risks and the ‘encounters’ your cat might have when outside, but indoor cats aren’t immune to bug bites either.

Cats are also predators, and they have a lot of fun catching flies or other bugs.

There’s no saying in what insects and bugs have touched or the places they’ve been before meeting your playful feline, that’s why cats may get swollen lips from trying to catch them.

The swelling caused by bug bites should disappear in a few days.

However, if they touched a bug that carried some substance your cat is allergic to, this might not be the case and they will need a medical examination.

Food Bowls 

Cats can have more or less sensitive skin, just like humans. One of the items they come in contact with more often is of course their food and water bowls.

These bowls can easily provoke contact dermatitis or EGC if bacteria linger on them, but the material they’re made of plays an important role as well.

In fact, plastic bowls are known to be the worst type of bowls your pet can have. They’re not dangerous for cats only, they’ve been proven to cause skin problems to dogs as well.

That’s because plastic contains chemicals that might ignite an allergic reaction in your pet. On top of that, bacteria are more likely to linger on plastic rather than other materials.

If you had a plastic bowl for a long time, that doesn’t rule out the possibility that your cat lip swelling is caused by the bowl. In fact, your cat might develop an adverse reaction to plastic in the long run.

Try substituting your cat’s plastic bowls with stainless steel or ceramic bowls.

Stainless steel bowls are considered the best type of bowls for pets. Remember to wash your cat’s bowl often and regularly to avoid lingering bacteria.

Environmental Causes 

This category is very vague because it refers to the specific habits and the environment that your cat lives in.

Outdoor cats are bound to visit different places and there’s no saying in what material, food, ground, or living being could give them a swollen lip or other kinds of issues.

However, the life of indoor cats is not void of risks. Even the cleanest house is bound to have some dust, dirt, or other materials lying around every now and then.

As cats are very curious and exploratory by nature, it doesn’t take much for them to come in contact with something that might cause an allergic reaction or even a light form of dermatitis.

How many times has your cat sneaked under a chair or a piece of furniture? That’s one of the easiest ways to get swollen lips on cats.

It’s impossible to restrain a cat, especially if it’s an indoor one that doesn’t have a lot of stimulation by default, so they should have the freedom to explore and play as long as it’s a safe environment.

Swollen lips caused by these unfortunate circumstances are often innocuous and should pass on their own. However, if a cat’s lip is swollen for more than a few days, don’t hesitate to contact your veterinarian.

Dental Issues 

Sometimes dental issues are behind a cat’s swollen bottom lip. A dental abscess, rotting tooth, or infected gums could provoke swelling in the lips or face.

In this case, the swollen lip might be the last symptom you notice, because dental issues are rarely without pain, and your cat will likely do one or more of the following:

  • Whine incessantly
  • Avoid food even when they’re clearly hungry
  • Drool
  • Have extremely bad breath (more than usual)
  • Shake their head for apparently no reason
  • React aggressively or painfully when you touch their face, mouth, under their chin

Dental issues shouldn’t be underestimated because they’re likely to get worse with time. Your veterinarian will recommend medications or surgery to remove the problematic tooth or the infected tissue.

Chin Acne

Did you know that cats can get acne? Not many people are aware of a condition called chin acne, which is often overlooked or not recognized at all because its symptoms are easily confused with other conditions.

This skin disorder is actually called follicular keratinization, where there is an overproduction of keratin in the outer layer of the skin that gets trapped in the hair follicle.

Chin acne can be a consequence of using plastic bowls because it exposes the cat to bacterial contamination.

Poor grooming habits are another cause of chin acne, so it’s not uncommon to see this disorder in older cats that cannot manage to groom themselves properly anymore.

When the acne affects hair follicles near the mouth, it may look like your cat has a swollen lower lip.

However, this condition has nothing to do with the oral cavity and another symptom is usually the dirty appearance of the chin.

Chin acne is diagnosed through clinical signs, but sometimes blood tests and skin cultures may be needed.

Treatment usually involves products to flush out the hair follicles and improve the hygiene of the pet.


A swollen lip might be, in rare cases, the symptom of an oral tumor, specifically feline oral squamous cell carcinoma, or FOSCC.

This kind of tumor is the most common oral tumor in cats, but it doesn’t mean it’s a common tumor. It usually occurs in old cats and affects the lower jaw and lip.

This tumor might affect other parts of the mouth, and cause great discomfort for your pet. A cat affected by this carcinoma has difficulty eating and might share the same symptoms as a cat with dental issues.

Luckily, metastasis for this kind of tumor is rare, but a more accurate assessment can only be done after a thorough medical examination.

The veterinarian will decide whether to proceed with treatment or surgery and will help you assess the quality of your cat’s life in the future.

What Should You Do if Your Cat has a Swollen Lip?

A cat with a swollen lip is not necessarily a medical emergency, but you should nonetheless monitor your cat closely until they get better.

When the swelling is due to their diet, their food and water bowls, or another recent change in their routine, it is enough to remove the problematic item from their daily life and wait for the swelling to pass.

During the summer season, it’s not uncommon for cats to be bitten by mosquitoes or other bugs. In that case, as well, the swelling should subside in a couple of days.

More often than not, outdoor cats come in contact with dirt, unknown materials, or other animals or insects that might provoke such a reaction.

Indoor cats are also at risk of developing swollen lips from eating the wrong food or sneaking under a dusty piece of furniture.

The wisest thing to do is to call the veterinarian right away, however, some pet parents might be reluctant because a trip to the vet can easily become an expensive situation.

Often, a cat with a swollen lip will be fine in a few days, but in the case that the swelling doesn’t go away on its own after 2-3 days, or if it seems to be getting worse, it’s absolutely mandatory that you call your veterinarian.

A medical examination is the only way to find out if the swelling is due to a particular allergy, a dental issue, or another medical condition, and in some cases, it might save your cat’s life.

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