Do Flea Collars Make Dogs Sick? 

Pet owners understand the importance of keeping your dog healthy and free from parasites like fleas. One of the biggest questions that comes up when considering ways to protect against these pests is “do flea collars make dogs sick?” While they can be an effective tool in preventing infestations, many pet owners are concerned about potential health risks associated with using them. Read below to learn about the safety of flea collars and tips on how to minimize any negative health impacts on your pup. 

Potential Risks of Flea Collars 

Flea collars are made with active ingredients that are designed to prevent and kill fleas. Depending on the brand, the active ingredients in flea collars may be amitraz, organophosphates, carbamates, or pyrethrin/pyrethroids. These compounds act as pesticides to prevent flea infestations but can be toxic to your pup if they ingest the contents of the collar. Ingestion can occur if your dog licks its fur, as the ingredients are designed to last on the skin for a long time. It can also occur if your dog holds the collar in its mouth. For some dogs, a long-term topical exposure is enough to cause discomfort, itching, and skin irritation.  

Flea Collar Toxicity  

The active ingredients in flea collars can affect the cardiac, gastrointestinal, and central nervous systems. Symptoms of flea collar toxicity includes: 

  • Lethargy 
  • Staggered walking 
  • Dilated pupils 
  • Seizures 
  • Coma 
  • Drooling 
  • Vomiting 
  • Diarrhea 
  • Bloating 
  • Slowed heart rate 
  • Low or high blood pressure 


If you suspect that your pup is sensitive to flea collars, it’s recommended to remove it immediately and call your veterinarian and Pet Poison Helpline at (855) 764-7661 for medical advice. If your dog has ingested the contents of a flea collar, you must seek medical attention right away. Depending on when the ingestion occurred, treatment may include inducing vomiting and administering activated charcoal to bind the toxins. IV fluids will help dilute the pesticide concentration in the blood. If you have concerns that your dog is having a reaction to its flea collar, do not hesitate to call Pet Poison Helpline for assistance.