Toxic to dogs · Medications

Is Isoniazid toxic to dogs?

Extreme severity No safe amount — No amount is considered safe.

Yes. Even a small amount can be life-threatening — treat any exposure as an emergency and contact a vet immediately.

Symptoms to watch for

  • drooling
  • vomiting
  • diarrhea
  • abnormal heart rate
  • organ injury
  • walking drunk
  • tremors
  • seizures
  • coma
  • death

How vets treat it

Call your veterinarian or Pet Poison Helpline immediately for life-saving treatment advice.

Why it's dangerous

Isoniazid has a narrow margin of safety in pets and can cause severe neurological and systemic toxicity, leading to seizures and organ injury.

Toxic compound: Isoniazid

Good to know

Commonly used for tuberculosis in humans; has a very narrow margin of safety in dogs and cats.

Sources

This page is informational and is not veterinary advice. If your pet has been exposed to something risky, contact your vet or an animal poison control line right away.

More substances toxic to dogs

5-fluorouracil (5-FU) Extreme severity Amphetamines Extreme severity Antibiotics Extreme severity Antihistamines Extreme severity Everything toxic to dogs →

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