Toxic to dogs · Medications

Is 5-fluorouracil (5-FU) 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

  • vomiting
  • diarrhea
  • tremors
  • seizures
  • bone marrow suppression
  • death

How vets treat it

Immediate veterinary treatment is necessary for the best patient outcome after exposure.

Why it's dangerous

The topical medication causes acute gastrointestinal distress, severe neurological impairment, and bone marrow suppression when ingested by pets.

Toxic compound: 5-fluorouracil

Good to know

Clinical signs occur within 30 minutes to 6 hours. Even a single lick can be highly toxic.

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

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