Why Is My Cat Foaming at the Mouth?

Salivation in cats is controlled by the brain in response to signals from inside and outside the body. There are many triggers for the production of saliva ranging from the anticipation of eating, to excitement and toxic substances in the blood. 

The most common cause of a cat foaming at the mouth is a reaction to a bad taste from something they’ve licked or eaten. Other causes of excessive salivation include behavioral causes, envenomation, nausea and facial focal seizures. 

Why Is My Cat Foaming at the Mouth?

I’d like to discuss some of the many reasons to explain why your cat is foaming at the mouth. Some of these are very common and others are uncommon. Consider your cat’s age, general health and what he’s exposed to in his environment when trying to figure out why he’s drooling. Your veterinarian can help you by doing a physical exam and running diagnostic tests. 

Bad Taste in the Mouth

This is probably the number one reason cats foam at the mouth. They’ve licked or eaten something bitter, rotten or just nasty tasting (in their opinion). 


Any oral medication can cause excessive cat drool and foaming at the mouth. The one I’ve seen cause foaming most reliably is metronidazole–a common antibiotic/antiparasitic given to cats for diarrhea. Tramadol and gabapentin seem to be especially distasteful to some cats, too. 

Household Cleaning Products

You probably don’t even think about all the things your cat comes into contact with in your home. If you use something like Pine-Sol® to mop your floor, your cat’s paws will pick it up when they walk through a freshly cleaned area. Cats are so fastidious that they immediately lick any body part that gets wet or dirty. When they get that little taste of cleaner, bam! Drool city. 

Larger exposures to concentrated cleaners can also cause oral ulceration and gastrointestinal distress. I once had a cat patient who slid through a puddle of straight Mr. Clean® and had an extremely sore, drooly mouth for about a week after licking the cleaner off his coat.

Cat is foaming at mouth
Lucky bamboo might not be so lucky if your cat chews it!


House and yard plants practically beg your cat to nibble on them. Some plants are very toxic, but many others are just oral irritants or have a yucky taste to a cat. A couple of perfect examples are the Peace Lily (Spathyphyllum sp.) and the Lucky Bamboo plant. Both can cause drooling and foaming at the mouth when cats chew them. 

Read more  Are Spider Plants Poisonous To Cats?

Check out the ASPCA Poison Control Center’s list of toxic plants to make sure you remove those from any area your cat can access. 

Grooming Products

Anything you apply to a cat’s body is fair game for them to lick. Things like waterless shampoo, perfumes, shampoo and conditioner can all cause buckets of cat drool to flow. Make sure you rinse your cat very well after bathing and think twice about applying anything to her fur. 

Essential Oils

Some essential oils can cause adverse reactions in cats that include excessive salivation. This mainly occurs when a cat licks an oil, but even breathing it or having skin contact with essential oil can cause symptoms. Some of the essential oils known to cause drooling include citronella and peppermint oils.

Be sure to dilute all essential oils and avoid applying them directly to your cat. Dr. Melissa Shelton has recommendations about using essential oils safely with cats on her site AnimalEO.com. 

Cat is foaming at mouth
This scared cat might salivate a lot from nervous system overstimulation.

Behavioral Causes

Secretion of body fluids is influenced by the sympathetic and parasympathetic nervous systems. Saliva will flow more or less in various states of arousal. 

Your cat might start to drool when she’s very content while being petted or when she sees another cat outside and gets all worked up. Different emotions make the saliva flow for different cats, but might include: 

  • Fear
  • Anxiety
  • Arousal/Excitement
  • Happiness/Contentment


Certain bugs, toads and snakes make toxic venom that can lead to saliva foaming in a cat’s mouth. It can happen from oral contact with the venom or as a systemic reaction to a bite or sting. Venomous creatures known to cause hypersalivation in cats include:

  • Bees and wasps 
  • Black widow spider 
  • Bufo toad (Colorado River/Sonoran Desert toad; marine/cane toad)
  • Snake envenomation (Coral snakes in the U.S.)

Gastrointestinal Problems

Since the mouth and salivary glands are technically part of the gastrointestinal (GI) tract, excessive drooling can result from practically any problem between the mouth and the anus. 

Some of the most common problems that affect a cat’s GI tract and could lead to saliva running from the mouth include pancreatitis, esophageal problems, and inflammatory bowel disease. Other problems of the feline GI tract

  • Intestinal obstruction
  • Food intolerance/garbage gut
  • Hiatal hernia 
  • Tumors
  • Constipation

Oral Cavity Problems

Next, I want to review a few problems that affect the mouth and surrounding structures. 

Dental Disease

Dental problems are very common in cats and their severity increases with age. Often you can tell a cat has dental disease by lifting their lip to see heavy calculus on the teeth (look at the big teeth in the cheek area) and gum inflammation just at the edge of the tooth.

But even if you don’t see these obvious signs of dental disease, your cat can still have serious problems under the gumline. If your cat has excessive salivation, your vet will probably want to rule out dental problems by taking X-rays of the teeth while your cat is anesthetized.  

Read more  Cat's Upset & Sensitive Stomach: Treatments & Food Choices


Stomatitis is a condition that affects the soft tissues of the mouth with inflammation. Many cats with stomatitis also have dental disease, but not all of them do. Stomatitis is associated with viral infections like FIV and Feline Leukemia but it can also be an immune system disease.


Sialadenitis is inflammation and infection of one or more salivary glands. This can cause poor appetite, swelling around the throat and jaw, bad breath odor and drooling. A biopsy is required to make a diagnosis. A culture of the tissue sample can identify the bacteria involved and help your vet choose the best antibiotic to treat the condition.

Oral Tumors

Cancerous and non-cancerous tumors can form on the lips, gums, tongue or the throat. The presence of the tumor can cause pain or obstruct swallowing, so you might notice saliva running or foaming from the cat’s mouth. 

It’s hard to detect oral tumors until they become pretty sizable, but you definitely need the help of your vet if you suspect any kind of bump in your cat’s mouth. Getting a biopsy and aggressive therapy will give your cat the best chance for recovery.


Nausea can occur when a cat has a GI problem as I discussed above. But things outside the GI tract can also cause nausea. There is an area in the brain called the chemoreceptor trigger zone in the brain that leads to vomiting when it senses toxins in the blood. The toxins might be from metabolic waste products or from something the cat ate. 

Here are some other causes of nausea in cats we see frequently in the vet clinic:

  • Kidney insufficiency
  • Viral infection
  • Parasites
  • Motion sickness

Neurologic Reaction

The brain and peripheral nervous system have a great deal of influence on salivation in cats. Let’s cover some of the reasons cats vomit that stem from things that affect their nervous system.


Dexmedetomidine is an injectable anesthetic that is used frequently to sedate and anesthetize cats. One of the great things about this drug is that we have a way to reverse its effects with another injection. The reversal drug is called atipamezole and one of the known side effects is hypersalivation. 

Any anesthetic can cause drooling through their general effect on the central nervous system. These effects are usually only seen during the recovery period, say maybe 30-60 minutes in most cases. 

Focal Facial Seizure

Orofacial or focal facial seizures are relatively common in the cat and can cause lip-smacking and foaming at the mouth. These kitties don’t lose consciousness but may have twitches in their facial muscles. 

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The causes of focal facial seizures include inflammation, infection, cancer, immune-mediated disease and trauma. 

Liver Disease

Liver disease can cause foaming at the mouth or drooling for a couple of different reasons. First, it can cause nausea and second it can cause metabolic toxin buildup in the blood that affects the brain (hepatic encephalopathy). 

Vestibular Disease

Vestibular disease affects a cat’s inner ear that is responsible for sending messages to the brain about body position. Anything that causes inflammation in the inner ear can cause a cat to feel like they’re spinning on a merry-go-round. I’m sure you can see how that could lead to nausea and drooling!


Finally, I want to mention a couple of common toxins that make cats drool a lot. 


Pyrethrin is a natural insecticide made from Chrysanthemum plants. Pyrethroids are synthetic versions of pyrethrin and are used in topical flea and tick preventives used on dogs and cats. 

Pyrethrins kill fleas and ticks by causing overstimulation of nerve cells. While cats are much less sensitive to this effect than fleas and ticks, pyrethrins/pyrethroids can still cause nerve cell stimulation that can make a cat foam at the mouth. This effect is often caused by a cat licking the product but very sensitive cats might not have to lick pyrethrin to have neurological effects. 

Use great caution when applying spot-on over-the-counter flea preventives on cats. Products made for use on dogs that contain pyrethroids can be way too strong for cats! 


Amitraz is an older insecticide used in “dips” and contained in collars to kill mites and ticks. Overdosage from ingestion of amitraz can cause hypersalivation, wobbly gait and other depressive effects. 


When your cat is foaming at the mouth, there is a logical set of questions you can ask to home in on the cause:

  1. Has he eaten something or licked something that tastes bad?
  2. Has he been outside and exposed to envenomation or trauma?
  3. Does he have any other symptoms like vomiting, poor appetite or wobbly gait?
  4. Does he seem either relaxed and happy or scared and anxious?
  5. How long has the problem been going on?
  6. Is he elderly?

If your cat is conscious but has a sudden onset of drooling or foaming at the mouth, you can try rinsing his mouth gently with warm water. If the problem continues or the kitty has other symptoms, take him to see a veterinarian right away.

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About the Author: Tung Chi