Pictured: Isoniazid

Poisonous to: Cats, Dogs

Level of toxicity: Generally severe, life-threatening

Common signs to watch for:

  • Drooling
  • Vomiting
  • Diarrhea
  • Abnormal heart rate
  • Organ injury
  • Walking drunk
  • Tremors
  • Seizures
  • Coma
  • Death

Isoniazid is an antimycobacterial agent used for the treatment of tuberculosis in human medicine. While it is sometimes used in veterinary medicine for the treatment of certain types of infection (Mycobacterium bovis, M. tuberculosis), it has a narrow margin of safety can be deadly when dogs and cats ingest them. Common signs with isoniazid poisoning include drooling, vomiting, diarrhea, abnormal heart rate, organ injury, walking drunk, tremors, seizures, coma, and death.

If your dog or cat ingested isoniazid, call your veterinarian or Pet Poison Helpline immediately for life-saving treatment advice.

Poison type: medications

Alternate names: INH, tuberculosis medication