Why Is My Cat Foaming at the Mouth? According to a Vet

Let me tell you about Pickles the cat. He was a sweet, energetic young cat with a stool problem. We had prescribed some medication to firm up his stool, but his owner was unable to give it to him at home. She brought Pickles to the clinic for the vet techs to show her how to get the small pills into his mouth. 

Well, as sweet as Pickles was, he really did not understand what we were trying to do. He struggled as the tech tried to pop the metronidazole pill in the back of his mouth. He must’ve bitten into the bitter pill because he immediately started shaking his head, chewing and drooling a lot. Soon he had foamy saliva all over his face! The look on his face said, “Yuck!!!”

In cats, the brain regulates salivation in response to signals from both inside and outside the body. Saliva production is triggered by a variety of factors, including hunger, excitement, and poisonous compounds in the blood.

When you see your cat foaming at the mouth, your first thought should be, “What did he lick?” Oral contact with a foul-tasting substance is the most common reason a cat produces foamy saliva. Excessive salivation can also be caused by behavioral factors, envenomation, sickness, and facial focal seizures.

Why Is My Cat Foaming at the Mouth?

I’d want to go over a few of the various reasons why your cat is foaming at the mouth. Some of them are extremely common, while others are extremely rare. When trying to figure out why your cat is drooling, think about his age, general health, and what he’s exposed to in his environment. A physical examination and diagnostic tests performed by your veterinarian can assist you in identifying the cause of excessive salivation.

1. Bad Taste in the Mouth

This is perhaps the most common reason for cats to salivate excessively. They’ve licked or eaten anything that tastes sour, rancid, or just bad (in their opinion).

Oral Medication

Any oral drug can produce excessive drooling and mouth foaming in cats. Metronidazole, a typical antibiotic/antiparasitic given to cats for diarrhea, is the one that consistently causes foaming. Tramadol and gabapentin appear to be particularly unappealing to some cats.

Remember that cats can lick topical medication off their fur, too. Flea and tick control products like Frontline® Top Spot and Advantage® can make a cat drool like crazy if they lick it.

Certain Plants

Cats like to explore and nibble leaves of house and yard plants. Not all plants are actually poisonous, but even some non-poisonous plants act as oral irritants or have a very bad taste to a cat. Two very common house plants, Peace Lily (Spathyphyllum sp.) and Lucky Bamboo, can both cause drooling and foaming at the mouth after cats chew them. 

ASPCA Poison Control Center has a good list of toxic plants you should beware of if you share your home with cats.  

Household Cleaning Products

You might never have considered everything your cat comes into contact with in your house. If you mop your floor with a cleaner like Pine-Sol®, your cat’s paws will pick it up when they walk across the wet, clean floor. Cats are so meticulous that they lick any damp or unclean body area right away. When they get a taste of the bitter cleaner, their mouth turns foamier than a Pumpkin Spice Latte.

Concentrated household cleaners can cause mouth ulcers and tummy pain. I treated a cat who accidentally ran through a puddle of undiluted ammonia-based kitchen cleaner. He had an extremely sore, drooly mouth for about a week after he attempted to clean the cleaner from his paws by licking it!

Shampoo, Etc.

Your cat will lick just about anything you put on them. Grooming products like waterless shampoo, perfumes, regular shampoo and conditioner can all trigger excessive salivation. Always rinse your cat thoroughly after bathing and think twice before you apply anything to her fur. 

Essential Oils

There are some essential oils that can cause adverse reactions in cats including foaming at the mouth. It’s most likely to happen after a cat licks the oil, but even breathing it or having skin contact with essential oil can sometimes cause drooling. Citronella and peppermint oils are two that can cause adverse reactions in cats..

You should always dilute all essential oils and don’t apply them directly onto your cat. Dr. Melissa Shelton shares a lot of good advice about using essential oils safely with cats on the site AnimalEO.com. 

White cat with open mouth (why is my cat foaming at the mouth?)
Bubbly saliva usually means your cat tasted something very yucky!

2. Natural Behavior Response

The sympathetic and parasympathetic nervous systems regulate bodily fluid secretion. In varying stages of arousal, a cat produces more or less saliva.

When your cat is happy and being handled, she may begin to drool. Another trigger might be when she sees another cat outside and becomes agitated. Saliva flow is caused by a variety of emotions in cats, including:

  • Fear
  • Nervousness
  • Excitement
  • Contentment

3. Insect Stings, Etc.

Toxic venom produced by certain bugs, toads and snakes can cause saliva foaming from a cat’s mouth. It can arise as a result of oral venom contact or as a systemic reaction to a bite or sting. The following venomous creatures can cause hypersalivation in cats:

  • Bee and wasp stings
  • Black widow spider bite
  • Sonoran Desert toad, Cane toad (oral contact)
  • Poisonous snake bites (Coral snake, Copperhead, Rattlesnake, etc.)

4. Tummy Troubles

Due to the fact that the mouth and salivary glands are technically part of the gastrointestinal (GI) system, excessive drooling can be caused by almost any condition involving the gut.

Pancreatitis, esophageal difficulties, and inflammatory bowel disease are some of the most prevalent issues that affect a cat’s GI system and can result in saliva flowing from the mouth. 

Other feline gastrointestinal issues that can cause salivation:

  • Dietary indiscretion (cat ate something they shouldn’t have)
  • Constipation
  • Intestinal obstruction
  • Hiatal hernia 
  • Tumors

5. Mouth Problems

Diseases that affect the mouth and surrounding tissues can definitely cause a cat to foam at the mouth. Let’s review a few of the more common conditions… 

Dental Disease

In cats, dental disorders are fairly frequent, and the severity of the disease worsens with age. When you lift a cat’s lip,  heavy calculus on the teeth and red gums are indications of dental disease.

Even if you don’t see these indicators of dental disease, your cat could be suffering from major issues hidden under the gumline. If your cat has excessive salivation, your veterinarian will need to rule out dental problems by obtaining X-rays of your cat’s teeth while he or she is anesthetized.  


Stomatitis is an inflammatory illness that affects the soft tissues of the mouth. Although many cats with stomatitis also have dental disease, this is not the case for all of them. Stomatitis is sometimes linked to viral diseases such as FIV and Feline Leukemia in cats, but it can also be an immune system disorder.

Salivary Gland Problems

Sialadenitis is a condition in which one or more salivary glands become inflamed and infected. Poor appetite, swelling around the throat and jaw, terrible breath odor, and drooling are all symptoms of this condition. To make a diagnosis, a biopsy is required. A tissue culture can identify the bacteria present and assist your veterinarian in selecting the best antibiotic to treat the disease.

Oral Tumors

Tumors on the lips, gums, tongue, and throat can be malignant or non-cancerous. You may see saliva streaming or frothing from the cat’s mouth if the tumor is causing pain or obstructing swallowing.

Oral tumors are difficult to detect until they are quite large, so seek the advice of your veterinarian if you see anything unusual in your cat’s mouth. Your cat’s greatest chance for recovery is to get a biopsy and intensive treatment.

6. Nausea

Many GI conditions cause nausea. However, nausea can also be caused by problems beyond the GI tract. Poisons in a cat’s bloodstream trigger the chemoreceptor trigger zone in the brain. This protective mechanism causes a cat to vomit in an attempt to remove toxins from the stomach. Although toxins may have come from something the cat ate, this can also happen in response to metabolic waste building up in the blood as happens with liver and kidney disease.

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

  • Motion sickness
  • Kidney disease
  • Gastrointestinal parasites
  • Viral illness

7. Nervous System Response

Salivation in cats is heavily influenced by the brain and peripheral nervous system. Let’s take a look at how a cat’s nervous system responses can make them vomit…


Dexmedetomidine is a common injectable drug used to sedate and anesthetize cats. One of the best aspects of this medicine is that its effects can be reversed by injecting a reversal agent drug. Hypersalivation is one of the known negative effects of the reversal drug, atipamezole.

Any type of anesthesia has the potential to cause drooling. Excessive salivation occurs mainly during the 30-60 minute recovery period immediately after the cat wakes up. 

Seizure Disorder

Orofacial or focal facial seizures are somewhat common in pet cats. Caused by uncontrolled electrical activity in the brain, this kind of seizure may cause lip-smacking and foaming at the mouth. Cats affected by focal facial seizures may have twitches in their facial muscles but don’t lose consciousness. 

Causes of this type of feline seizure include infection, cancer, inflammation, trauma and immune-mediated disease. 

Liver Disease

For a variety of reasons, liver problems can produce foaming at the mouth or drooling. It can cause stomach/intestine irritation, and it can also cause a buildup of metabolic toxins in the blood, which can harm the brain (hepatic encephalopathy).

Vestibular Disease

The vestibular apparatus is located in a cat’s inner ear. This amazing set of organs sends information about body position to the brain. Anything that causes inner ear inflammation can interfere with the vestibular apparatus and make a cat feel like they’re spinning on a merry-go-round. 

And you can probably imagine how that could cause nausea and drooling!

8. Toxins

I want to discuss a few specific toxins we see frequently causing side effects, including excessive salivation and foamy mouths in cats. 

Pyrethroid Chemicals

Pyrethroids are synthetic versions of the natural insecticide, pyrethrin. Many spray and spot-on topical flea and tick preventives contain concentrated pyrethroids. 

Pyrethroid chemicals overstimulate the nerve cells of fleas and ticks. Cats are much less sensitive to this effect but the chemical can cause enough nerve stimulation to lead to saliva foam in the mouth. If your cat licks the chemical, they’re more likely to drool but some cats have the same reaction just from having the product on their skin. 

Be very careful if you use over-the-counter flea preventives on your cat. Pyrethroid flea/tick preventives made for dogs should not be applied to cats. Check the label if you’re in doubt. 


Amitraz is an insecticide used in “dips” and contained in collars to kill mites and ticks. It is not as popular as it used to be, but it’s still present in some products like tick collars. Amitraz can cause hypersalivation, wobbly gait and other depressive effects if an animal is very sensitive or receives an overdose. 


If you see your cat foaming at the mouth, don’t panic but do think about the following questions:

  1. Did he taste something bad?
  2. Has he been outside? Consider envenomation and trauma.
  3. Do you see other symptoms like vomiting, poor appetite or wobbly gait?
  4. How is he acting? Is he happy and relaxed or scared and hyperactive?
  5. When did the symptoms start?
  6. Is your cat older than 11 years or does he have a chronic disease?

If your cat seems mentally alert but is drooling heavily, gently rinse his mouth with warm water if you can do so without injuring yourself or the cat. Take your kitty to a veterinarian straight away if the problem persists or if he exhibits other symptoms.

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