Flea and Tick Medicine Poisoning in Dogs

Barri J. Morrison, DVM
By Barri J. Morrison, DVM. Reviewed by Michael Kearley, DVM on May 5, 2024
A pet parent gives flea and tick preventative to their pup.

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What Is Flea and Tick Medicine Poisoning in Dogs?

It’s crucial for your dog to be on flea and tick prevention to help minimize the risk of disease. However, there are important guidelines to prevent toxicity when giving these medications to your pup. Substances that are toxic to fleas and ticks can also be harmful to pets when consumed or applied in large quantities.

Active ingredients found in common flea and tick medications include naturally derived pyrethrins, synthetic pyrethroids, or a newer class of drugs, isoxazolines, which were the first oral flea and tick products.

While they are all highly effective, they can cause toxicity if given incorrectly or if an overdose occurs.  

These preventions are generally safe to use if the appropriate dose is administered. Dogs can also become exposed at toxic quantities through the ingestion or absorption of household insect sprays, foggers, and granules. 

Common brands of pyrethrins/pyrethroids include:

Isoxazoline-containing preventives include:

Keep in mind there are many more generic and brand-name preventives that include these ingredients.

Symptoms of Flea and Tick Medicine Poisoning in Dogs

Toxicity associated with flea and tick preventatives can cause a variety of symptoms that can develop within 15 minutes to several hours after ingestion or application to your dog’s skin.

These symptoms include:

If you think your dog is having toxic side effects from the ingestion or absorption of pyrethrins, pyrethroids, or isoxazolines, call your veterinarian, ASPCA Poison Control, or the Pet Poison Helpline immediately for potentially life-saving treatment advice.

Depending on the severity of clinical signs, seek emergency vet care immediately.

Causes of Flea and Tick Medicine Poisoning in Dogs

Dogs often become poisoned unintentionally either through the misuse of flea and tick prevention or through the accidental ingestion or absorption of insecticides. 

Prior to medicating your dog, verify the correct drug, dose and size of the product and that the proper time frame in between doses has occurred nor that someone else in the family already gave it.   

Additionally, don’t give expired medications or cut larger sizes into smaller pieces or give multiple smaller doses. 

If the product is labeled for cats, do not give it to your dog—or vice versa.

Not all products may result in toxic symptoms as products contain varying concentrations of drug but be sure to consult your veterinarian immediately if noted.

How Veterinarians Diagnose Flea and Tick Medicine Poisoning in Dogs

After a complete physical examination, your veterinarian will make a presumptive diagnosis if there is a known or possible history of exposure to a product containing a pyrethrin or pyrethroid, or ingestion of flea/tick medicine.

In a presumptive diagnosis, a veterinarian has a good reason to believe that something is causing the problem but can't prove it with a specific diagnostic test.

Blood work and urine testing may help rule out other possible causes.

Treatment of Flea and Tick Medicine Poisoning in Dogs

Depending on the severity of the toxicity and the symptoms your dog is displaying, treatment could be on an outpatient basis, or your dog might need to be hospitalized for supportive care.

There is no antidote for these types of poisoning.

Treatment includes quick removal of the product by bathing your dog with a liquid dish soap like Dawn®, Joy®, or Palmolive® to get the greasy substance off and rinsing the mouth with copious amounts of water.

Use a garden hose, if necessary, to help flush from the mouth any toxins ingested.

In cases where neurologic signs occur, it’s helpful to minimize the extent and severity of them by having your dog hospitalized, which could require several days.

Supportive care might consist of:

  • Repeat bathing

  • Intravenous (IV) fluids

  • Anti-nausea medications

  • Muscle relaxation

  • Seizure medication

Your veterinarian might also want to monitor your dog’s temperature, blood sugar levels, and kidney function, since these can be affected by toxicity in dogs.

Recovery and Management of Flea and Tick Medicine Poisoning in Dogs

With prompt recognition and early treatment, the prognosis is good.

If your dog develops neurologic signs, kidney issues, seizures, and elevated body temperature, the prognosis is generally poor.

Adverse reactions such as excessive drooling, paw flicking/scratching, and ear twitching are often mild and can go away on their own.

Although drooling may recur for several days after use of a flea-control product, most mild to severe symptoms resolve within a few days.

Prevention of Flea and Tick Medicine Poisoning in Dogs

To prevent accidental exposure, follow all directions on flea and tick preventives and insecticides very carefully. Ensure that your dog only receives his prescribed medication as flea and tick preventatives are dosed on body weight.

Also, make sure that you do not give more than one drug at a time, as that can cause an accidental overdose and can possibly interact with other medications. Speak to your veterinarian about the risk of drug interactions.  

Do not use part of a larger-sized dose or multiple smaller doses, as this may result in an overdose and increased chance of poisoning. When in doubt, bring your dog to the veterinarian for proper dose.

Barri J. Morrison, DVM


Barri J. Morrison, DVM


Barri Morrison was born and raised and currently resides in Ft. Lauderdale, Florida. She went to University of Florida for her...

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