Cat Foaming At The Mouth: Causes and Treatment

Last Updated on October 13, 2021 by Julia Wilson

At a glance


  • Nausea
  • Bitter tasting substances or medications
  • Poisoning
  • Spot-on flea treatments
  • Dental disorders
  • Seizures
  • Rabies
  • Anxiety

Diagnosis: Thorough physical examination and medical history. Baseline blood and urine tests and additional diagnostics depending on your veterinarian’s index of suspicion.


Foaming at the mouth and drooling are both characterised by the presence of excess amounts of saliva, I tend to define foaming at the mouth as saliva which is frothy, compared to drooling which is watery, but sometimes both are used interchangeably.



Just like humans, cats can become car sick, which may result in drooling/foaming at the mouth due to the feeling of nausea. Other signs of nausea may include a loss of appetite and lethargy.

Common causes of nausea include:

  • Kidney disease
  • Pancreatitis
  • Certain medications
  • Car/travel sickness
  • Umbilical hernia
  • Diabetes
  • Motility disorders (an abnormal movement of food through the gastrointestinal system)
  • Liver disease
  • Hyperkalemia (high blood potassium)
  • Stomach ulcer
  • Gastritis (inflammation of the stomach lining)
  • Hyperthyroidism
  • Hepatic lipidosis
  • Pregnancy (morning sickness)
  • Anxiety

Bitter tasting substances

Oral and eye medications are a common cause of this as they often have a bitter taste to them.

Eye medications such as atropine can also cause a cat to foam at the mouth as once administered into the eye the medications eventually reach the back of the throat, producing a distinctly bitter taste in the mouth. Other bitter-tasting medications include Flagyl (Metronidazole) and Benadryl, an over the counter antihistamine.

If the medication has been prescribed to your cat and administered as per instructions, then there is little to worry about if foaming at the mouth is the only symptom, although it is always important to let your veterinarian know. Offer your cat a small meal or a treat after he’s had his medication to help get rid of the bitter taste.

If the administration of a bitter-tasting medication becomes a problem for you or your cat, you can ask your veterinarian about having the medication compounded. Compounding medication can give it a more palatable flavour such as tuna, which is more palatable for your cat. Or the medication can be in liquid form instead of a tablet form.


There are so many potential hazards out there, and cats are particularly vulnerable. Poisons that can cause frothing of the mouth include pyrethrins, poisonous toads, plants, snail bait. Watch for additional symptoms of poisoning including confusion, ataxia (wobbly gait), vomiting, diarrhea, lethargy and seek immediate veterinary attention. 

Spot-on flea treatments

If they are applied in an area your cat can lick, the unpleasant taste can cause excessive drooling and foaming. Always apply topical flea products to the back of the neck where your cat can’t reach.

Be aware, that cats are extremely sensitive to pyrethrin and permethrin which are used in canine topical flea products. If you suspect your cat has ingested a dog flea treatment, seek veterinary treatment immediately as this is a life-threatening situation.


Seizures (convulsions or fits) are the result of a sudden and uncontrolled burst of electrical activity within the brain. They are one of the most common neurological disorders in cats, although the prevalence is much lower than that of dogs. Seizures occur in the cerebrum, which is located in the front of the skull and is responsible for sensory and neural functions as well as behaviour.

Dental problems

Several problems can affect the mouth, including a broken tooth, gum disease, and stomatitis. Common symptoms of dental problems may include loss of appetite, bad breath, and pain around the mouth.


A fatal viral infection caused by the rhabdovirus. In the late stages of this disease, foaming at the mouth can occur. Rabies is a rare disease in cats as most cats in the US have been vaccinated for rabies, and thankfully it doesn’t occur in Australia or the UK.

Any time you notice your cat foaming at the mouth, look for other symptoms he may be displaying. Ask yourself, has he recently had any medication, is it possible he has got into something he shouldn’t have? If you are in any doubt whatsoever, seek veterinary attention.


Find and address the underlying cause of anxiety, such as inter-cat aggression or separation anxiety. In some cases, the veterinarian will prescribe anti-anti medications.

When to see a veterinarian

If your cat is drooling after administration of prescribed medication, call the veterinarian for advice, the chances are that it is just in response to the bitter taste and aside from it being unpleasant, and your cat possibly not getting the full dose, he will be okay.

It can be helpful to take the medication to a compounding pharmacy who can flavour it to make it more palatable to the cat.

Apart from bitter-tasting prescribed cat medications, seek urgent veterinary attention if your cat is foaming at the mouth. If your cat has ingested any medication, flea treatment or poison bring along the packaging for the veterinarian to look at.


The veterinarian will perform a complete physical examination of your cat and obtain a medical history from you.

Has the cat consumed something he or she shouldn’t have, are there any underlying medical conditions your cat has and have you noticed any additional symptoms?

Diagnostic workup:

Biochemical profile, complete blood count, and urinalysis will give your veterinarian an overall picture of your cat’s health including how the organs are functioning.

Depending on his index of suspicion he may need to perform additional tests to determine the cause. This may include diagnostic imaging of the internal organs, as well as specific blood tests.


Nausea – A symptom and not a disease itself, so determining the cause and treating is necessary. Anti-nausea medications can relieve symptoms.

Bitter tasting medications – Offer the cat a small amount of food or water immediately after administering medication or consider using a compounding pharmacy to make it more palatable to the cat.

Poisoning Gastric decontamination if the toxin was induced within the past two hours, this may include inducing vomiting or pumping the stomach. Activated charcoal can bind to any toxin remaining in the gastrointestinal tract. In addition, your cat will receive supportive care such as IV fluids to correct electrolyte imbalances and treat dehydration.

Topical flea products – Foaming at the mouth due to topical flea products should resolve quickly. Offer the cat some water and a small amount of food or a treat to get rid of the taste.

Remember to apply topical flea products to the back of the neck where the cat can’t reach. Never use topical products for dogs on your cat as these are extremely toxic.

Dog flea treatment ingestion – If you have applied a dog product onto your cat, or recently treated your dog and your cat may have been exposed, contact your veterinarian immediately as this is a medical emergency.

Treatment will depend on the severity of signs; control seizures and tremors as well as provide supportive care.

There is no antidote for pyrethrin/pyrethroid toxicity; the goal of treatment is to manage symptoms.

  • Diazepam (valium) and Methocarbamol to control seizures or tremors.
  • Gas anaesthesia may be necessary for refractory seizures (seizures that do not respond to seizure medication).
  • Fluid therapy to maintain hydration.

Seizures – The veterinarian will need to determine and address the underlying cause as well as administer medications to help control the seizures.

Dental problems – Treatment is on a case by case basis. Some cats will only require a clean and scale. Sometimes the affected tooth is so severely damaged that extraction under general anesthesia is necessary.

Rabies – There is no effective treatment for rabies in cats and euthanasia is necessary. Veterinarians are required by law to report any animal with rabies to regularity authorities.