Medication Guide • Reviewed by Dr. Tiffany Delacruz, DVM
Metronidazole for Dogs
Metronidazole is a prescription antibiotic and antiprotozoal often used in dogs for diarrhea, giardia, inflammatory bowel disease, and certain dental infections.
What Metronidazole is used for in dogs
- Diarrhea (especially large-bowel)
- Giardia infection
- Inflammatory bowel disease
- Some anaerobic bacterial infections
How it works
Metronidazole disrupts DNA synthesis in anaerobic bacteria and certain protozoa. It also has anti-inflammatory effects in the gut.
Available formulations
250 mg tablet
500 mg tablet
Compounded suspension
Side effects to know
Common side effects
- • Nausea
- • Decreased appetite
- • Drooling (the taste is bitter)
These usually resolve on their own. If they persist past the first few doses, ask your vet.
Call your vet immediately if you see
- ⚠ Neurologic signs (head tilt, ataxia, tremors) — especially at high doses
- ⚠ Severe vomiting or diarrhea
- ⚠ Liver toxicity (rare)
Drug interactions
- • Warfarin (anticoagulant interaction)
- • Cimetidine (raises metronidazole levels)
- • Alcohol-containing products
When not to use
- • Pregnant dogs (especially first trimester)
- • Severe liver disease (dose adjustment)
- • Dogs with documented neurologic toxicity history
Monitoring during treatment
Don't extend beyond the prescribed course unless instructed. Watch for any wobbling or balance issues, especially at higher doses.
Talk to a vet about Metronidazole
RexVet is the first 501(c)(3) non-profit online vet service in the U.S. Talk to a licensed veterinarian by video for $64.99 per visit.
Book a vet visit — $64.99Metronidazole for Dogs
Frequently asked questions
How long does it take metronidazole to work?
For diarrhea, most dogs improve within 24-72 hours. Complete the full course to prevent recurrence.
Why does my dog hate the taste?
Metronidazole is famously bitter. Hiding it in food, pill pockets, or asking a vet for a flavored compounded version usually helps.
Can metronidazole upset my dog's stomach?
Yes, ironically — it can cause nausea and decreased appetite. If GI signs worsen rather than improve, contact your vet.
Can RexVet prescribe metronidazole?
Not after a video visit alone. Metronidazole is a human-labeled drug, so a veterinarian needs to examine your pet in person before prescribing it.
Should my dog take a probiotic with metronidazole?
Often yes — many vets recommend a probiotic during and after the course to help restore healthy gut bacteria.
Medical review by Dr. Tiffany Delacruz, DVM
Chief Executive Officer & Lead Veterinarian, RexVet. Licensed in Florida, New York, and Virginia.
Last fact-checked: 2026-05-19
Sources
This page is an educational reference and does not replace veterinary advice. Always consult a licensed veterinarian before starting, changing, or stopping medication for your pet.