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Your Cat Has a Swollen Lip? Our Vet Explains Reasons & How to Act

Written by: Dr. Joanna Woodnutt BVM BVS (Veterinarian)

Last Updated on May 14, 2024 by Catster Editorial Team

cat with swollen lower lip contain being examine by vet surgeon at vet clinic

Your Cat Has a Swollen Lip? Our Vet Explains Reasons & How to Act


Dr. Joanna Woodnutt Photo


Dr. Joanna Woodnutt

MRCVS, Veterinarian

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

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Sometimes, when we get a swollen lip, it can be due to an allergic reaction, biting it, getting hit in the mouth, or an infection. But what about cats? Can a cat get swollen lips? Do cats even have lips? The answer to both of those questions is yes. If you have noticed your cat’s lips looking a bit swollen, there could be a few reasons for that. Read on to learn more. 

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Possible Reasons Why Cats Have a Swollen Lip

Lips are part of what is called a “mucocutaneous junction.” This means they are the border between the outside skin and the special skin that coats our mouths, eyelids, and other unmentionable internal structures. These junctions are prone to various issues in all species, and swollen lips can be a common sign of many problems.

The fact the lip is swollen implies that something is causing inflammation inside or around the lip. Lots of things can cause inflammation—swelling is a generic immune system reaction that the body has in response to many insults. The swelling itself is usually caused by a surge of white blood cells and fluids into the area, rushing to try and deal with a problem. Let’s have a look at some of the more common things that can cause swellings in lips:

1. Trauma

sad sick cat in bed
Image Credit: Julia Cherk, Shutterstock

Cats have a reputation for finesse and elegance, but experience will tell us that they quite regularly end up getting into accidents, scrapes, fights, and knocks. They sometimes lack common sense! It is not unusual for cats to go headfirst into a trauma, and the lips may be damaged through trauma.

Both trauma and any subsequent infection can lead to swollen lips. Typically, the lips would just be swollen in one place, and there may be other wounds around the head, ears, and neck. It is worth checking your cat’s claws—scuffed and damaged claws are a good sign a cat has been through something violent


A swollen lip over a couple of days that your cat may be licking or cleaning excessively, often seen with wounds or swellings to other parts of the head. The lip will probably look angry and be sore to touch. There may be discharge or pus from the swollen area, and cats may dribble from one side of the mouth. Your cat will otherwise be well and fairly relaxed.

2. Stings, Bites, or Reactions

This is usually more of a dog problem, as dogs love sticking their heads into things, but cats may also suffer from reactions to something like a sting, bite, or nettles. If your cat has chased and tried to eat a bee or wasp, for example, a sting to the mouth may cause swollen lips. These are allergic reactions but are usually mild. More severe allergic reactions (known as hives, urticaria, or anaphylaxis) are rare but also possible. Again, the lips will likely be swollen in just one place, though swellings may be found all over.


Sudden appearance (within hours) of a swollen lip—your cat may be holding the mouth open and breathing heavily or harshly. There may be swellings or lumps over the rest of the body. Sometimes, the whole head swells up! Your cat will be hypersensitive and agitated, often dribbling heavily from the mouth. There will typically not be any discharge from the swollen area, but you may see a small brown stinger from a bee or wasp—try and brush this out and away with a light touch from a finger if you can do so safely.

3. Mouth or Dental Disease

cat mouth check by vet
Image Credit: mojahata, Shutterstock

Cats are prone to diseases of the mouth and teeth. These are known as gingivitis or stomatitis, depending on what parts they affect and how severe they are. Like all animals, cats suffer from tooth decay, tartar, and plaque, but in cats, these can become much more complex and sinister than in other species due to the interactions between several factors in the mouth—bacteria, viruses (especially calicivirus), and the immune system itself.

Where most animals will develop slowly progressive plaque and tartar, cats’ bodies can have massive inappropriate reactions to the bacteria and viruses that live in the mouth and these cause huge amounts of inflammation even if the teeth visually look fairly clean and healthy. This can even cause the teeth to start to be re-absorbed back into the jawbone! As you can imagine, this disease is really painful and unpleasant, just as mouth pain is for us.


Slowly progressive swollen lips (over days to weeks or more) in several places, especially the corners of the lips. The swelling will get gradually worse, alongside other symptoms. Your cat may be slow or reluctant to eat, especially avoiding crunching hard things. You might notice he has bad breath. If you can see your cat’s teeth, there will be intense redness of the gums around some or all of the teeth, and there may be angry red patches on the tongue and roof of the mouth, too. Your cat may groom the mouth and lick, and there may be small amounts of dribble from the mouth. You might notice blood in the water bowl after your cat has had a drink.

4. Autoimmune Diseases

Autoimmune diseases, in general, are rare across all species. In humans, rheumatoid arthritis is a good example of how unpleasant these problems can be. Essentially, the immune system inappropriately attacks or damages some part of its own body.

Cats suffer from a particular group of diseases called eosinophilic granuloma complex, known as EGC or as indolent ulcers or rodent ulcers. These are not well understood and can be quite variable, but essentially, there is a flood of a type of white blood cells called eosinophils into a particular area of skin. The attack often happens in the mouth, lips, or throat but can occur anywhere on the cat’s body. This surge of cells causes pain, swelling, intense inflammation, discharge, and, oddly, can become infected too! They come in three main types but can look very different between cats.

EGC often has no clear cause but has been linked to various things that can trigger the immune system, including food intolerances, allergies to parasites such as fleas or mosquito bites, or something from the environment (pollens, for example), and viruses (especially feline immunodeficiency virus, FIV).


Swellings of the skin or mouth appear quite quickly (within days) and can be very itchy and sore. Ulcers affect the upper lip and roof of the mouth—they are raised, red, angry, and quite well-defined around the edges. Other types of EGC present as raised, angry areas of skin that are yellow/pink, painful, and weeping with discharge. Cats are usually otherwise well but are uncomfortable and may show difficulty eating. They may be grooming excessively and dribbling.

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Everything Else

This list is by no means exhaustive, and there are many reasons cats can get a swollen lip. Regardless of the cause, if you are concerned about your cat then you should seek professional, expert help from a veterinarian as soon as practical. Only a veterinarian can appropriately diagnose and treat these problems to ensure a quick and proper resolution for your cat.

What Should I Do if My Cat Has a Swollen Lip?

It is best to seek advice from your local veterinarian if your cat has a swollen lip. As above, there are many reasons cats can get swollen lips and they can be very painful and very difficult to manage. For the most accurate diagnosis and most appropriate treatment, your cat needs professional help as soon as practical. Any delay will cause extended unnecessary pain and discomfort. The biggest challenge is that all of these causes of swollen lips can look very similar, but all need different treatments—so an expert evaluation is needed to tell them apart and provide the proper care at the right time.

Home remedies are not appropriate, given the challenges in diagnosing and treating these problems. Diagnosis is not straightforward, and treatments are specific and may be quite intensive, depending on the cause of the problem. There are many home remedies available, but these are mostly either not of any use or can be actively harmful to your cat, so they are not advised. At best, they will delay your cat’s recovery and so extend pain unnecessarily. The best and fastest treatments come after a proper diagnosis from a professional veterinarian.

The only home remedy that could be reasonably performed in some cases is giving your cat time—if you suspect your cat has had trauma but is otherwise well and has a small lip swelling from a cut or knock, then allowing this to heal is not unreasonable. However, if your cat appears in pain or is unwell, then again, it is best to seek professional help at an early stage. If the swollen lip does not go away within a few days, then again, it is best to seek advice—the situation may be more complicated than you think.

veterinarian listening to cat's heart
Image Credit: TShaKopy, Shutterstock

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How Do You Treat a Cat With a Swollen Lip?

This depends heavily on the cause of the problem.

Cats with trauma or reactions to bites and stings usually need an anti-inflammatory to reduce the swelling and the pain. Where the area is infected, antibiotics may be useful but are not required in all cases. Typically, cats will make a full and speedy recovery from these issues.

Dental disease

Dental disease can be more challenging to deal with and can affect cats of any age. Minor cases may respond well to anti-inflammatory treatment alongside antibiotic therapy. More severe or chronic problems are usually approached initially by an assessment of the mouth under an anesthetic. This allows your veterinarian to fully assess all the mouth and teeth, take dental X-rays if needed, and give the teeth a really good clean to reduce the bacteria, plaque, and tartar in the mouth as much as possible. It may be better if severely affected teeth are extracted at the same time, as they will be causing intense pain.

Where appropriate, swabs may be taken to check for viruses in the mouth (such as calicivirus). Good mouth hygiene is vital in these cases, so your veterinarian may recommend dental care and treatment at home. Some cases may need long-term anti-inflammatory therapy. In the most extreme cases, the problem is only manageable by removing all teeth and so removing all surfaces where bacteria, plaque, and tartar can accumulate.

Veterinarian checks teeth to a big maine coon cat at vet clinic
Image Credit: Ermolaev Alexander, Shutterstock

Rodent ulcers

Eosinophilic granuloma complex (EGC, rodent ulcers) can again be challenging to manage. In most cases, a biopsy will be recommended to confirm the diagnosis and ensure treatment is appropriate. Your veterinarian will perform a thorough examination and talk with you to try and establish any triggering factors. If triggers are obvious, then it may be possible to avoid these in the future (through strict parasite treatment, for example).

Some cats benefit from a change of diet if food intolerance is suspected—your veterinarian may recommend a 6-to-8-week trial of a special hypoallergenic or hydrolyzed food, which, as long as it is the only thing your cat eats during the trial, can help diagnose intolerances. The best bit is that if it works, then you already have the long-term treatment for your cat, too!

Most cats with EGC require anti-inflammatory treatment that suppresses all those eosinophils, and the most common way to do this is with steroid therapy (usually with prednisolone or dexamethasone). These are safe, cheap, and widely available, with minimal side effects (though they will make your cat eat more, pee more, and drink more). Steroids may be needed just in the short term (especially if there is an obvious trigger to deal with), or sometimes over the long term, seasonally, or even over your cat’s lifetime (if there is no obvious trigger). If the EGC area is infected, short-term antibiotics may also be helpful.

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While not one of the more common cat problems, cats can develop a swollen lip for a variety of reasons. This can be a mild problem with an obvious cause or can be more long-term and problematic. In all cases, it can cause real pain and discomfort for your cat. If you are unsure, it is best to seek expert, professional advice from your local veterinarian as soon as practical. Many different diagnoses can all look very similar, but all require very different treatments. For the fastest and most appropriate resolution, get in touch with your veterinary clinic.

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Featured Image Credit: M. Sam, Shutterstock

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