Metronidazole (brand: Flagyl; dog-specific liquid brand: Ayradia) is a nitroimidazole antimicrobial—an antibiotic and anti‑parasite medicine. It is prescription‑only for dogs. A veterinary metronidazole oral suspension (Ayradia) is FDA‑approved for treating Giardia in dogs; other common canine uses are under a veterinarian’s direction (extra‑label).
Top reasons it’s prescribed: Giardia (a parasite that causes diarrhea), and certain anaerobic bacterial infections of the gastrointestinal tract; veterinarians may also use it for diarrhea associated with intestinal inflammation. Tablets can taste very bitter, so some dogs may drool if they chew them. Your veterinarian can discuss why this medication was chosen for your dog and how long it is intended to be used.
Most dogs do well, but call the clinic promptly if you see vomiting, worsening diarrhea, or marked loss of appetite. Treat as urgent if you notice new neurologic signs after starting the medication—stumbling or trouble walking, tremors, eye twitching, or seizures—and contact us or the nearest emergency clinic right away.
Front desk script: Metronidazole—also called Flagyl—is a prescription antibiotic/anti‑parasite medicine for dogs. We commonly use it for Giardia and for certain gut infections or diarrhea. There’s also a dog‑specific liquid form called Ayradia that’s FDA‑approved for Giardia. If you see severe side effects like stumbling, tremors, or seizures after a dose, please call us right away or go to the nearest emergency clinic. For details about your dog’s case and how long to use it, the veterinarian can go over that with you.
Common owner FAQs (short Q&A)
Q: Why was my dog prescribed metronidazole? A: It’s a prescription-only antibiotic/anti‑parasitic used by veterinarians for certain gastrointestinal infections and some anaerobic bacterial issues. In the U.S. it’s commonly used extra‑label in dogs under a veterinarian’s direction, which is normal and allowed. Your veterinarian can explain the specific reason for your dog.
Q: How fast will it help? A: It starts working within 1–2 hours, but you may not see improvement for a day or a few days depending on the condition. If you’re not seeing the expected improvement, your veterinarian can advise next steps.
Q: How should I give it? A: Give by mouth with food. The tablets are very bitter—do not crush them. If giving is difficult, your veterinarian can discuss alternatives (for example, flavored formulations) or tips to hide the taste.
Q: What if I miss a dose? A: If you remember soon after, give it then. If it’s close to the next scheduled dose, skip the missed one and resume the regular schedule—don’t double up. If multiple doses are missed, check with your veterinarian for guidance.
Q: What side effects should I watch for? A: Mild stomach upset, drooling (from bitterness), or tiredness can occur. Urgent signs include stumbling/wobbliness, tremors, seizures, eye twitching, or yellow gums/eyes (possible liver issue). If any urgent signs or a severe allergic reaction (hives, collapse, trouble breathing) occur, seek emergency care immediately and contact the veterinary team. Your veterinarian can discuss which effects are expected versus concerning for your dog.
Front desk script: Metronidazole is a prescription antibiotic/anti‑parasitic our doctor selected for your dog’s specific case. It usually starts working within a couple of hours, but improvements may take a day or a few days. Please give it with food and don’t crush the tablets because they’re very bitter; if that’s a problem, we can ask the veterinarian about options. If you miss a dose and it’s close to the next one, skip the missed dose—don’t double up. If your dog becomes wobbly, has tremors or a seizure, or you notice yellow gums or eyes, please go to the nearest emergency vet now and call us on the way.
What owners most often report with metronidazole: mild stomach upset (nausea, vomiting, diarrhea), decreased appetite, tiredness, and drooling right after giving a dose (the tablets are very bitter). Some dogs’ urine may look darker or reddish‑brown while on this medication; that color change has been reported with metronidazole and is not usually an emergency. Your veterinarian can discuss whether any formulation changes are appropriate if taste is an issue. ([vcahospitals.com](https://vcahospitals.com/know-your-pet/metronidazole))
Call the clinic the same day if GI signs are frequent or worsening, if there is blood in stool or vomit, if your dog won’t eat or is very lethargic, or if you notice yellow gums/eyes. Seek immediate care for any neurologic changes owners often describe as “wobbly/drunk walking,” stumbling, head tilt, eyes twitching back and forth, shaking/tremors, sudden weakness, or seizures—these can indicate rare but serious reactions that need urgent veterinary evaluation. Your veterinarian can advise on next steps and whether the treatment plan should be adjusted. ([vcahospitals.com](https://vcahospitals.com/know-your-pet/metronidazole))
Front desk script: Thanks for calling—some dogs on metronidazole can have mild stomach upset or drooling from the bitter taste. If vomiting or diarrhea is frequent, there’s blood, your dog won’t eat, or seems very tired, we’d like to see your dog today. If you notice wobbliness, twitching eyes, tremors, or any seizure activity, this is an emergency—please head to the nearest emergency clinic now and I’ll alert the team. Your veterinarian can review the medication and discuss any changes once your dog is assessed.
Forms and giving: Metronidazole comes as tablets/capsules and liquids. It is very bitter—do not crush or split tablets. Give by mouth with food to reduce stomach upset; shake liquids well. Wash hands after dosing; people who are pregnant should avoid handling crushed or broken tablets and avoid exposure to vomit/saliva when possible. Your veterinarian can discuss whether a flavored liquid (including the FDA‑approved oral suspension for dogs used for Giardia) or another form is appropriate if pills are difficult.
Pilling tips: Hide the pill in a very small amount of a safe, tasty food or a pill‑pocket, then follow with a regular treat so the dog swallows promptly. Offer a few “blank” treats first, give the medicated one, then another “blank” treat. If needed, a pill gun (pilling device) or direct placement of the tablet at the back of the tongue can help; watch to be sure it’s swallowed. If your pet has diet restrictions, ask the veterinarian which foods are allowed with this medicine.
Troubleshooting: If the dog spits out or vomits a dose, do not give another dose until the veterinarian advises—what to do depends on the medicine and timing. Call same day if your dog cannot keep doses down, has repeated vomiting/diarrhea, or you’re struggling to give it. Seek emergency care immediately for concerning neurologic signs (wobbliness, tremors, eye twitching, seizures). Compounded options (e.g., flavored suspensions or small capsules) are available; your veterinarian can advise which form best fits your dog.
Front desk script: This medication is very bitter, so please don’t crush the tablets. Give it with food and try hiding the pill in a tiny treat or pill pocket, then follow with another treat so they swallow it. If your dog vomits or spits the dose out, don’t re‑dose—call us and we’ll tell you what to do. If you notice wobbliness, tremors, eye twitching, or seizures, go to the nearest emergency clinic right away. If pills are a struggle, we can ask the veterinarian about a flavored liquid or other compounding options.
Metronidazole is a prescription‑only antimicrobial for dogs. A valid veterinarian‑client‑patient relationship (VCPR) is required before any prescription or refill can be approved, and refills should not be open‑ended; quantities are dispensed only as needed for the veterinarian’s plan. Many uses are short course; if a pet is requesting repeats or long‑term use, expect the veterinarian to review the case and may require a recheck exam and/or tests before authorizing more. Your veterinarian can discuss whether continued therapy is appropriate and the timing of any re‑examination.
When taking a refill request, collect: client and pet name, medication name and form (tablet vs oral suspension/compound), where it should be filled (clinic or licensed pharmacy), how much is left and the last dose given, any new medications, and any new symptoms. Standard turnaround is 1–2 business days for doctor review; urgent concerns are routed sooner. For online pharmacies, confirm they require a prescription and are U.S.‑licensed; our team will verify the request directly with the pharmacy. The exact product must match the veterinarian’s order (for example, human‑labeled tablets versus the FDA‑approved canine oral suspension); do not substitute—route requests for changes to the veterinarian.
Escalate immediately to medical staff if the caller reports possible adverse effects such as wobbliness/ataxia, tremors, eye twitching, severe lethargy, persistent vomiting, or seizures; seizures warrant emergency care. The veterinarian will advise on next steps and whether the medication should be adjusted or rechecked.
Front desk script: “Thanks for calling about a metronidazole refill for [Pet]. Because this is a prescription antibiotic, our doctor needs to review it under an active veterinarian‑client‑patient relationship. I’ll grab a few details: the exact medication and form, how much you have left and the last dose given, any new symptoms, and where you’d like it filled (our clinic or a licensed pharmacy). Turnaround is usually 1–2 business days—we’ll text or call when it’s approved. If you’re seeing wobbliness, tremors, eye twitching, severe vomiting, or seizures, please tell me now so I can alert our medical team immediately; seizures are an emergency.”
Escalate immediately if a dog on metronidazole shows any sudden neurologic signs: wobbling or stumbling, disorientation, head tilt, rapid eye flicking, body tremors or twitching, severe weakness, or any seizure. These can indicate metronidazole toxicity and may happen after extra doses or with longer courses—get a veterinarian or technician right away. Severe allergic reactions are emergencies: facial swelling, hives, trouble breathing, pale/blue gums, or collapse.
Same-day urgent escalation for repeated vomiting or diarrhea (especially with blood), refusal to eat, extreme lethargy, yellow gums/eyes, or very dark/tea‑colored urine, which can signal liver involvement. If the pet chewed the bottle, a double dose was given, the wrong strength was dispensed, or a different pet’s/human medication was given, alert medical staff immediately and be ready to contact animal poison control. Your veterinarian can discuss which side effects are expected vs. unsafe and what monitoring is needed.
Front desk script: Because you’re seeing [wobbliness/seizure/trouble breathing], this could be an urgent reaction to metronidazole. I’m alerting our medical team now—please come to the clinic immediately; if your dog is actively seizing or struggling to breathe, go to the nearest emergency hospital now. Bring the medication bottle and note the last dose and any extra doses or chewed tablets. If it’s after hours and you can’t reach us, call ASPCA Animal Poison Control at 888-426-4435 or Pet Poison Helpline at 855-764-7661. Our veterinarian will evaluate your dog and advise on next steps.
Key interactions to flag with metronidazole: cyclosporine (often for allergies/immune disease) because metronidazole can raise cyclosporine levels and side effects; phenobarbital or phenytoin (seizure meds), which can lower metronidazole levels and make it less effective; cimetidine/Tagamet (an acid reducer), which can raise metronidazole levels and side effects; certain chemotherapy drugs such as fluorouracil/5‑FU, which can increase 5‑FU levels and toxicity; and blood thinners like warfarin‑type products, which can increase bleeding risk. If any of these are mentioned, document the exact drug name and route to the veterinarian for review the same day before advising anything further. Your veterinarian can discuss safety, timing, and any monitoring if these drugs must be used together.
Common OTC items owners may give with GI issues: acid reducers (Tagamet/cimetidine; Pepcid/famotidine), anti‑diarrheals (Imodium/loperamide; Pepto‑Bismol/bismuth subsalicylate), and probiotics. Specifically flag Tagamet/cimetidine due to a known interaction with metronidazole. For any other OTCs, note the product and amount given and defer recommendations—your veterinarian can advise what’s appropriate alongside metronidazole.
Escalate immediately if the owner reports concerning signs while the pet is on metronidazole: wobbliness or loss of coordination, tremors, seizures, eye twitching, or unusual bruising/bleeding. Advise the owner to seek emergency care now and notify the veterinarian so the case can be triaged urgently.
Front desk script: Thanks for letting me know about the other medication. Because it can interact with metronidazole, I’m going to flag this for our veterinarian to review today so we can confirm it’s safe together. Please keep the bottle handy so we have the exact name and strength. If you see wobbliness, tremors, seizures, or unusual bruising or bleeding, please head to the nearest emergency vet right away and call us on the way. Your veterinarian can go over what’s safe to use together and any monitoring needed.
Storage basics: Keep metronidazole tablets/capsules in the original, tightly closed, child‑resistant container at controlled room temperature (about 68–77°F/20–25°C), protected from light and moisture. Avoid bathrooms, vehicles, and other hot/humid areas. For the FDA‑approved canine liquid metronidazole (Ayradia), store the bottle upright below 86°F (30°C); it does not require refrigeration and should be used within 6 months after first opening. Compounded liquids may have different storage needs and shorter beyond‑use dates—follow the pharmacy label exactly. If a product was left in a hot car, frozen, got wet, or tablets look damaged, your veterinarian can advise whether it’s still okay to use.
Handling and safety: Keep all metronidazole out of sight and reach of children and pets; flavored liquids can be especially tempting. Wash hands after handling tablets/capsules and avoid skin contact with Ayradia; if contact occurs, wash the area thoroughly. If Ayradia is mixed with food, keep that food away from children until the dog has finished eating. Direct any owner questions about unusual storage situations, label changes, or container damage to the veterinarian.
Disposal: Do not share leftover medication. Use a drug take‑back program when possible. If no take‑back is available and the medicine is not on the FDA flush list, mix it (do not crush tablets) with an unpalatable substance like used coffee grounds or cat litter, seal in a bag/container, and place in household trash; remove personal information from labels. Do not flush unless label/specific FDA guidance says to do so. If a pet chews into the bottle or anyone (pet or person) may have swallowed extra doses, contact the clinic or an emergency vet immediately and consider calling an animal poison control service (Pet Poison Helpline 855‑764‑7661 or ASPCA Animal Poison Control 888‑426‑4435).
For most short courses of metronidazole in dogs, there is no routine lab work required. Schedule any recheck exactly as the prescribing veterinarian indicates. If no recheck was specified, advise owners that many dogs show improvement within a few days; if signs are not improving or are worsening, book the next available exam with the prescribing doctor so they can reassess. Your veterinarian can discuss the ideal timing based on the pet’s condition and any other medications.
Bloodwork may be requested when a dog has known liver disease, is on a longer or repeated course, or is taking other medications that could interact. In those cases, the veterinarian may ask for a baseline chemistry panel and follow‑up liver values—please confirm test timing with the doctor before booking.
Ask owners to monitor at home for side effects such as vomiting or diarrhea, drooling (the drug is bitter), decreased appetite, or unusual tiredness. Escalate immediately if there are neurological signs (wobbliness/stumbling, tremors, rapid eye movements, seizures) or yellow gums/skin/eyes—advise emergency care right away. Your veterinarian can advise on whether any milder signs are expected or if adjustments are needed.
Front desk script: I’ll schedule the recheck exactly as the doctor noted. Routine bloodwork usually isn’t needed for short courses, but if your dog has liver issues or a longer course is planned, the doctor may want lab tests—I’ll confirm that with the veterinarian. Please watch for vomiting, diarrhea, drooling, or unusual tiredness and let us know if you’re concerned. If you see wobbliness, tremors, unusual eye movements, seizures, or yellow gums/skin/eyes, please go to the nearest emergency hospital now and call us on the way.
Metronidazole (brand name Flagyl) is a prescription antibiotic and anti-parasite medicine commonly used in dogs. Mild stomach upset can happen; giving with a small meal can help, and tablets should not be crushed because they are very bitter. If a dose is missed or if there are questions about refills or combining with other medications, the veterinarian can advise; do not give extra doses without veterinary guidance. Pregnant people should avoid handling this medication if possible and wash hands after contact.
Urgent red flags to escalate immediately: wobbliness or stumbling, tremors, eye flicking, seizures, severe or persistent vomiting/diarrhea, yellow gums or eyes, or signs of an allergic reaction (facial swelling, hives, trouble breathing). In these cases, direct the client to emergency care now and notify the doctor.
Phrases to avoid: “It’s okay to stop or change the dose,” “Double up a missed dose,” “It’s just an antibiotic—no worries,” or giving any diagnosis. Use deferral language instead: “Your veterinarian can discuss dosing, duration, and whether it’s appropriate for your dog.”
Front desk script: Thanks for calling [Clinic Name], this is [Your Name]. I can help with questions about your dog’s metronidazole. It’s a prescription antibiotic/anti-parasite medicine; mild tummy upset can occur, and giving it with a small meal may help—please don’t crush the tablets because they’re very bitter. If you see wobbliness, tremors, eye flicking, seizures, severe vomiting/diarrhea, yellow gums/eyes, or any swelling or trouble breathing, please go to the nearest emergency vet now and I’ll alert our doctor. For missed doses, refills, or how long to give it, our veterinarian can advise—would you like me to send a message or schedule a quick callback?