Adverse reactions from essential oil-containing natural flea products exempted from Environmental Protection Agency regulations in dogs and cats

J Vet Emerg Crit Care (San Antonio). 2012 Aug;22(4):470-5. doi: 10.1111/j.1476-4431.2012.00780.x. Epub 2012 Jul 16.


Objective: To describe adverse effects in dogs and cats exposed to Environmental Protection Agency exempted plant-derived flea preventatives containing mixtures of essential oils.

Design: Retrospective study from 2006 to 2008.

Setting: Records of dog and cat cases were reviewed from the American Society for the Prevention of Cruelty to Animals, Animal Poison Control Center database.

Animals: Thirty-nine cats and 9 dogs with history of exposure to natural flea preventatives.

Measurements and main results: The following information was retrieved from each incident: number of animals, species involved, frequency, types, onset time, duration of clinical signs, exposure appropriateness, final outcome, and treatment information. Ninety-two percent of animals (n = 44) showed presence of one or more adverse effects. The frequency of adverse effects in dogs (n = 8; 89%) and cats (n = 36; 92%) was similar. Onset time of adverse effects in 39 of 44 animals occurred within 24 hours. The duration of signs in 24 animals ranged from 30 minutes to 149 hours. The products were used as per label in 77% animals (n = 37). Of 28 animals with known outcome, 50% (n = 14) recovered with bathing alone while others received intravenous fluids, muscle relaxants, and anticonvulsive medications. Death (1 cat; n = 1/28; 4%) or euthanasia (1 cat and 1 dog; n = 2/28; 7%) was reported in 3 animals.

Conclusion: Dogs and cats can experience significant adverse effects when exposed to plant-derived flea preventatives even when used according to label directions. The number of reports of exposure in cats was higher than dogs, but the frequency of reported adverse effects was similar between the 2 species. Agitation and hypersalivation were common in cats, whereas lethargy and vomiting were common in dogs.

MeSH terms

  • Administration, Topical
  • Animals
  • Cat Diseases / chemically induced*
  • Cat Diseases / parasitology
  • Cats
  • Dog Diseases / chemically induced*
  • Dog Diseases / parasitology
  • Dogs
  • Flea Infestations / drug therapy
  • Flea Infestations / veterinary*
  • Insecticides / administration & dosage
  • Insecticides / adverse effects*
  • Insecticides / chemistry
  • Lethargy / chemically induced
  • Lethargy / veterinary
  • Oils, Volatile / adverse effects*
  • Oils, Volatile / chemistry
  • Plant Oils / adverse effects*
  • Plant Oils / chemistry
  • Retrospective Studies
  • Seizures / chemically induced
  • Seizures / veterinary
  • Tremor / chemically induced
  • Tremor / veterinary


  • Insecticides
  • Oils, Volatile
  • Plant Oils