Pictured: Antihistamines

Poisonous to: Cats, Dogs

Level of toxicity: Generally mild to severe

Common signs to watch for:

  • Agitation
  • Lethargy
  • Sedation
  • Aggression
  • Abnormal heart rate
  • Abnormal blood pressure (hypertension)
  • Vomiting
  • Diarrhea
  • Inappetance
  • Seizures
  • Respiratory depression
  • Death

Antihistamines are used commonly in both human and veterinary medicine for allergies, hay fever, skin disease, etc. When accidentally ingested by dogs and cats, antihistamine poisoning can result in clinical signs of severe agitation, lethargy, sedation, aggression, abnormal heart rate, abnormal blood pressure, vomiting, diarrhea, inappetance, seizures, respiratory depression, and even death.

If you suspect your dog or cat were poisoned by antihistamines, contact your veterinarian or Pet Poison Helpline immediately for life-saving treatment recommendations.

Poison type: medications

Alternate names: Benadryl, Caldryl, Dermamycin, Ziradryl, diphenhydramine, DPH