Can a dog overdose on flea and tick medicine? What to Know

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Symptoms of Flea and Tick Medicine Poisoning in Dogs

  • Pyrethroid-based topical flea and tick preventives, especially “spot-on” formulas, cause symptoms that can develop from 15 minutes to several hours after application to your dog’s skin. Clinical signs include:
    • A tingling sensation; dogs will excessively itch or scratch that spot on their skin
    • Scratching, intense itchiness
    • Agitation or restlessness
    • Rolling around on the back or trying to bite the back
    • Vocalization, crying, whimpering
  • Pyrethrin and pyrethroid toxicity after oral ingestion usually causes clinical signs within 1 hour of absorption or exposure. Clinical signs may include:
    • Drooling
    • Vomiting
    • Lack of appetite
    • Gagging or hacking
    • Agitation

    • On rare occasions, bifenthrin (frequently used in liquids and granular fire ant products.) ingestion, in large concentrated amounts, can cause:

    • Tremors
    • Twitching
    • Shaking
    • Difficulty standing or walking
    • Weakness
    • Seizures
    • Death
  • Isoxazoline (commonly found in oral flea and tick preventatives) overdose can cause:
    • Muscle tremors
    • Difficulty standing or walking
    • Seizures

    • If you think your dog or cat is having toxic side effects or was exposed to pyrethrins or pyrethroids, call your veterinarian, ASPCA Poison Control, or a 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

    The formulations of pyrethrins and pyrethroids vary depending on how they will be used. Pyrethrins and pyrethroids typically come in varying concentrations. Higher concentrations can be safely used on dogs, but cats are more sensitive to these chemicals and cannot metabolize these drugs.

    Intended uses of these products include:

  • Home and outdoor yard and garden insecticides, which typically come in liquids, sprays, granules, and foggers
  • Over-the-counter medicated flea shampoos
  • Topical flea and tick preventives

    • Common brands of pyrethrins/pyrethroids include:

  • Advantix
  • Vectra 3D
  • Advantage sprays and home fogger
  • Seresto collars
  • Hartz products

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

    Signs of flea or tick medication toxicity in cats:

  • Cat acting nervous
  • Twitching
  • Shaking/tremors
  • Seizures
  • Drooling
  • Vomiting
  • Diarrhea
  • Lethargy
  • Incoordination

    • Flea Medication Poisoning

    Lufenuron is used to control fleas on dogs and cats. It is not used in humans, but humans might accidentally take an animal’s medication or come into contact with it in the form of an agricultural spray. Minor side effects such as GI upset and drowsiness might occur if that happens. No human overdoses have been published.

    Fleas are small (up to 1/8 inch), blood-sucking insects. They live on warm-blooded animals such as dogs and cats. Not only do they cause irritating, itchy bites, they also are capable of transmitting diseases and parasites such as typhus, plague, and some tapeworms. A heavy infestation of fleas can cause iron deficiency anemia due to blood loss, particularly in young animals. When a dog or cat becomes infested with fleas, pet owners need to thoroughly clean all bedding, rugs, floors, and carpets as well as treat all animals in the home. A good bath and flea comb are important tools to remove fleas and their eggs from fur. A veterinarian can recommend a medication to control fleas after this. The egg, larval, and adult stages of fleas must all be killed for flea control to be successful.