Dog’s Lip is Swollen and Red: How to Help

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lip and mouth inspection at the vet

This article was updated on September 1st, 2023

Swelling and redness in a dog’s lip can stem from a variety of issues: bug bites, dental issues, allergies, injuries, and tumors top the list. Some are very minor and require little further attention, and some are severe and need professional care as soon as possible.

In this article, our expert veterinarians explore the most common causes of swollen, red lips in dogs, illustrated with pictures, and explain when you should be concerned.

swollen red lip on dog

Top Causes of Swollen, Red Lips in Dogs

1. Insect bites and Stings

When an insect is making a nuisance of itself, your dog’s first instinct is to snap or bite at it, hoping it’ll go away. All of that is fine until the bug fights back. Insect bites and stings elicit an inflammatory reaction that causes swelling, redness, heat, and pain, often in a dog’s lips.

  • These swellings usually show up suddenly and can become quite large.
  • You may also find a stinger lodged in the skin or a small, bloody area where the bite went down (see example in the picture below).
bug or insect bite on a dog's lips

Most insect bites are harmless and the swelling will go away with an antihistamine, icing, and time; however, rarely dogs can have an allergic reaction that leads to anaphylactic shock or the swelling can be severe enough to make breathing difficult.

Swollen face of dog stung by a bee

You can also click this picture to see a swollen lip on a dog after a bee sting.

2. Allergies

Dogs can have allergies to bug bites, pollen, grasses, plants, and chemicals. Some allergic reactions cause swelling of the lips and face, as well as these other frequent symptoms:

English bulldog with red swollen lips due to an allergy

As with insect stings, most allergic reactions will calm down with antihistamines and removal of the allergen, but swelling can be severe enough to cause difficulty breathing. Be sure to get a hold of your vet if you notice any moderate to severe swelling of your dog’s lips or face.
Learn more about skin issues from allergies.

3. Dental Issues

Dental disease is very common in our canine companions. So common, in fact, that it’s estimated that over 80% of dogs over three years of age have some stage of dental disease. Symptoms include:

  • bad breath,
  • bleeding gums,
  • loose teeth,
  • tooth root abscesses that can create swellings in the jaw and even in the lip covering it (mainly in the lower jaw)
  • you may also notice a foul odor, drainage, or drooling,
  • your dog probably won’t want to eat due to the pain.
Tooth abscesses can cause swellings in the mouth and lips

Tooth root abscesses are going to need antibiotics and a veterinary dental, so get them to the vet as soon as you can.

4. Benign growths or cancerous tumors

Tumors can show up anywhere on your pup, including the lips. Lip lumps and bumps can be malignant (cancerous) or benign and may look and act differently depending on the type of growth. Tumors of the lips can be slow-growing or grow large very quickly. This makes it important to have any new lumps, bumps, or swelling checked out by your veterinarian as soon as you can for the best outcome.

Pictures of tumors and growths on a dog lips:

warts on a dog's lips
Benign warts
Possible squamous cell carcinoma, melanoma, or mast cell tumor.
Possible cancerous lip tumor (swollen red lump)

Learn more about lip lumps and bumps (with pictures and vet advice).

“If your dog’s lips are swollen and red, but the situation doesn’t seem too serious, you can always take pictures and email them to your vet to ask for advice.”

Dr. Chyrle Bonk

Veterinarian at

5. Injuries

Dogs love to stick their noses in things, which can sometimes get them into trouble. Injuries to the lips or nose can cause swollen and red lips. It may be due to a small scrap with another animal, a well-positioned kick, or a run-in with a vehicle. You may notice:

  • other wounds
  • bleeding along with the swelling,
  • your pup may be a little disoriented or act as if they have a headache.

If your pup suffered any trauma to their head or mouth, it’s always best to have them checked out by a veterinarian to help ensure that they don’t have further injuries that could be serious.

6. Other causes

Snake bites, foreign objects, and minor irritations can also lead to a dog with swollen and red lips (View this dog with swollen lips and face after being bitten by a rattlesnake). These can be very minor or quite severe, causing your dog a lot of distress. If you notice any swelling or redness in your dog’s lips, be sure to contact your vet to determine the cause and how to best treat it.

At-Home Treatments for Dog With Swollen and Red Lips

If you notice a swelling in your dog’s lips, you should really contact your vet to make sure it’s not something very serious. While you wait for your appointment, try the following:

1. Find the cause. Inspect the swelling, if your dog is willing, to see if you notice any wounds, stingers, or rotten teeth that could indicate the cause.

2. Note the size and timeframe with pictures if possible. If the swelling is growing rapidly, you may want to show your vet how quickly it is growing.

3. Give an antihistamine if your veterinarian suggests it. They will provide you with the best medication to use as well as the dose. Note that you should never administer medication to your dog without first checking with your vet.

4. Apply ice or a cold pack to the swelling. Don’t apply it directly to the skin.

When to be Concerned

“You’ll want to check out any new swellings or lumps on your dog’s lips, but that doesn’t mean that you always need to rush right over. If your pup’s lip is only mildly swollen and they’re not having difficulty breathing, eating, or drinking, or if they are not showing other signs of illness, you may wait and see if things get better with a little time.”

Dr. Chyrle Bonk

Veterinarian at

When to visit your vet as soon as you can:

  • your pup’s lips and face or throat are swollen so severely that they are having trouble breathing
  • you can see pus or smelly drainage – this should be addressed as soon as possible
  • your dog isn’t feeling like eating or drinking
  • your dog is showing signs of discomfort or illness

Veterinary Treatment

Your veterinarian is going to start with a thorough exam, including a history of when the swelling showed up, if it’s grown or gotten smaller, and any other signs your pup is showing. Hopefully, you’ll know the cause, but if not, your vet may have to dig a little deeper by:

  • checking your dog’s teeth,
  • doing an x-ray, or
  • taking a sample of the swelling with a needle and syringe (learn more about biopsies)

Based on those findings, they will start treatment:

  • Allergic reactions, including insect stings and bites, are often treated with antihistamines and icing, and anti-inflammatories for those more severe cases.
  • Tooth root abscesses will be treated with antibiotics, a dental, and possibly removal of the tooth.
  • Injuries may be treated with antibiotics, anti-inflammatories, and other medications.
  • Tumors may need surgical removal with or without chemotherapy and radiation.


A dog lip that is swollen and red from an insect sting may only cost you around $75 for the exam and medications, while a tumor of the lip can run $2,000+ for surgery and aftercare. Everything else is going to fall somewhere in between, but generally speaking, most cases of swollen lips are going to be under $500.

Can a Vet Diagnose Swollen Lips With a Picture or Video Call?

Telemedicine has become popular in the veterinary world lately, but it can’t completely replace the need for a vet to get their hands on an animal. Some swollen lips can be seen this way and others are still going to need an in-office appointment.

Of course, if your dog is in distress, having trouble breathing or eating and drinking, don’t even consider a video call. If the swelling also has a foul odor or discharge, telehealth is not an option. If you suspect a tumor, you’ll need to make the in-office journey.

Those dogs that have mild swelling that is probably related to an insect bite or mild irritation are the only ones that you can fully rely on telemedicine.


  • Dr Chyrle Bonk, Veterinarian

    Dr. Chyrle Bonk received her Master in Animal Science from the University of Idaho and her Doctorate of Veterinary Medicine (DVM) from Oregon State University in 2010. She has over 10 years of experience in small animal veterinary practice, working for a veterinary clinic in Idaho.

Disclaimer: This website's content is not a substitute for veterinary care. Always consult with your veterinarian for healthcare decisions. Read More.


  1. I’m grateful for the information and picture. My 8-year old 110# black has a red fleshy spot on his lower lip. Not sure for how long…? But it’s been a while. Must be bigger to grab my attention. We live on 5 wooded acres in western Washington. He does seem to have allergies with skin, sneezing, etc. Will continue to watch for now as we are on a fixed income. He has no pain or difficulty eating. He’s a lab! LoL

    • Hey there Shari and thanks for this new question.
      If this lump has been there for more than 2 weeks, I’d want it looked into. This is especially true given his age and breed. The vet may biopsy it, to determine if it could be cancerous. If so, the sooner it is removed, the better the prognosis.

      While allergies can cause lip lesions/swellings, they would not cause any sort of fleshy mass to grow.

      “The information on this website is not a substitute for in-person veterinary care. Always seek advice from your veterinarian if you have concerns about your pet’s medical condition.”

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