Metronidazole for Dogs: Uses, Side Effects and Alternatives

Metronidazole for Dogs

Dog diarrhea is a challenge for any dog owner and their pet. When evaluating treatment options, Metronidazole, often called Flagyl, is a commonly prescribed drug for to treat both chronic and acute diarrhea.

Even though Metronidazole for dogs is a well-known treatment, fully understanding its effects is crucial to your dog’s health. This medication effectively stops diarrhea but it can deliver potential side effects that could harm your dog over time.

Let’s look at Metronidazole for dogs, how this antibiotic works, its possible downsides, and natural alternatives you can try. You can soothe your dog’s upset stomach without the risk of long-term side effects, so let’s explore a healthier, more natural way to treat diarrhea and bacterial infections.

How Metronidazole Works in Dogs

Metronidazole is a prescription medication that’s commonly prescribed for bacterial and parasitic infections. It’s an antibiotic that works by killing the bacteria or parasites that are causing the infection. 

When a dog is given metronidazole, this prescription medication is absorbed into the bloodstream and distributed throughout the body. It then enters the cells of the bacteria or parasites and interferes with their ability to replicate and grow. This ultimately leads to the death of the bacteria or parasites, which allows the dog’s immune system to clear parasitic or bacterial infections.

Metronidazole is most effective against anaerobic bacteria, which are bacteria that don’t require oxygen to survive. These bacteria are often found in areas of the body that have low oxygen levels, such as the intestines. By targeting these bacteria, metronidazole can help to treat diarrhea, oral and dental infections, and manage inflammatory bowel disease and colitis.

In addition to its antibacterial properties, metronidazole also has anti-inflammatory effects. This means that it can help to reduce inflammation in the body, which can be beneficial for dogs with inflammatory bowel disease or other inflammatory conditions.

Overall, metronidazole is designed to target anaerobic bacteria and reduce inflammation, which can make it a versatile option for a range of conditions. But, like all drugs, these benefits come at a cost: side effects.

The Problem with Using Metronidazole to Treat Diarrhea

To start, it’s important to understand that, at the time of writing, Metronidazole isn’t FDA approved for veterinary use. But there are other problems with this veterinary medicine for issues in the digestive tract:

While Metronidazole is effective when used to treat bacterial infections and protozoal infections, it’s a short acting medication that doesn’t treat the root cause of diarrhea. 

Recent research has cast a cloud over the usefulness of Metronidazole for dogs. One clinical trial examined dogs with acute hemorrhagic diarrhea. Dogs treated with Metronidazole, Amoxicillin, Clavulanic Acid and supportive therapy showed little improvement.

So the jury is still out on the potency of Metronidazole for dogs. As of today, the FDA hasn’t even approved veterinary use of this medication.

Side Effects of Metronidazole in Dogs

When you give your dog Metronidazole, you need to be prepared for side effects. Here are some of the more common side effects of this drug:

Neurological Issues: Includes, head tilt, lethargy, coordination problems, nystagmus (rapid back and forth eye movements) and seizures.

Gastrointestinal Issues: Includes nausea, vomiting, blood in the urine, decreased appetite, changes in liver enzymes.

Allergic Reactions: Includes hives, rashes or difficulty breathing.

Drug Interactions: Metronidazole can interact with other medications including warfarin, Phenobarbital, Cimetidine, sedatives, Fluorouracil and some chemotherapy drugs, other antibiotics and cyclosporine.

Other Adverse Effects

Most cases of Metronidazole toxicity involve very high doses or chronic use of smaller doses. This can be a problem if Metronidazole treatment is used to manage chronic diarrhea.

Metronidazole is also used to treat central nervous system infections because it can penetrate the blood-brain barrier. But that also means it can cause neurologic symptoms. 

Finally, dogs taking Metronidazole suffer the same unwanted gut changes as they would from any antibiotic. Metronidazole indiscriminately kills both pathogenic and beneficial gut bacteria, which can make diarrhea worse, cause an allergic reaction or activate inflammatory mechanisms in the immune system. 

Long-term use of Metronidazole can result in liver disease, liver toxicity, kidney disease and more. If your dog is on Metronidazole, be sure to contact your veterinarian immediately if you see any of these symptoms. 

Natural Remedies: Alternatives To Metronidazole for Dogs

If you are interesting in using Metronidazole to treat diarrhea in your dog, you might want to try these natural alternatives first:


Fasting is one of the best things you can do to relieve your dog’s upset stomach. Stop feeding him for a short period of time and let his gut work out its issues on its own. 

Some dogs will fast themselves. If this happens, don’t encourage him to eat.

Even if he seems hungry, try fasting your dog for anywhere between 6 hours to as long as a day. It gives his digestive system a break and time to heal. When your dog’s symptoms start to improve, go slow as you reintroduce food and water back into his diet. 

Caution: don’t fast young puppies under 6 months old.

Healthy Foods

As he recovers, give your dog something simple, bland, and nutritious. Bone broth is one such solution. When feeding your dog, you can serve broth on its own or add light servings of meat and mashed vegetables. 

You can also feed your dog pre- and probiotic foods to rebuild his gut health. Probiotics help balance good bacteria in the gut. And prebiotics feed the probiotics, making them more effective.

Foods like jive yogurt, kefir, and fermented vegetables are a great source of probiotics. Meanwhile mushrooms, chicory root, garlic, and dandelion greens are some options full of prebiotics.

Or, you can give your dog probiotic supplements.

Herbs as an Effective Treatment

There are a variety of other supplements and herbs that can treat your dog’s upset stomach and naturally treat diarrhea:

Slippery ElmHerbs from this tree can cause mucous secretion, which can relieve your dog’s stomach. Give a ¼ tsp of powder for every 10 lbs of body weight. Mix the powder into food or some yogurt.

L-Glutamine: This is an amino acid that can heal the cells inside your dog’s intestines. Give 500 mg per 25 lbs of body weight per day.

Marshmallow Root: Generations of societies have used this herb to treat digestive problems. In tincture form, 0.5-1.5 ml per 20 lbs, 2-3 times per day. Or give a supplement that contains marshmallow root.

Digestive EnzymesThese can improve your dog’s digestive function by preventing malabsorption

Bach Flower Essences: Stress is often a cause of doggy diarrhea. Bach flower remedies can calm your dog’s emotional stress.

Our Final Verdict on Metronidazole for Dogs

If your dog has diarrhea, you may want to skip the Metronidazole. There are better natural solutions that can help his upset stomach. Metronidazole only provides your dog a short-term fix for anaerobic bacterial infections and other health issues. It suppresses the symptoms associated with your dog’s problematic gut. What Metronidazole doesn’t do is actually cure your dog’s underlying gut issues.

As a result, you may find yourself giving Metronidazole to your dog over the long haul. And long-term, chronic use can yield some scary, negative effects. When it comes to your dog’s health, the best bet is to go with a natural approach. Your dog’s future self will thank you when you do.


1. What are the common side effects of Metronidazole for dogs?
Answer: The common side effects of Metronidazole for dogs include vomiting, diarrhea, loss of appetite, lethargy, and neurological symptoms such as seizures and tremors.

2. How long do the side effects of Metronidazole for dogs last?
Answer: The duration of the side effects of Metronidazole for dogs varies depending on the severity of the symptoms and the dosage administered. In most cases, the side effects subside within a few days after discontinuing the medication.

3. What should I do if my dog experiences severe side effects from Metronidazole?
Answer: If your dog experiences severe side effects from Metronidazole, such as difficulty breathing, swelling of the face or limbs, or severe neurological symptoms, seek immediate veterinary attention.

4. Can Metronidazole for dogs cause long-term side effects?
Answer: Metronidazole for dogs can cause long-term side effects such as liver damage or neurological damage. These side effects usually occur with prolonged use or high doses of the medication.

5. Are there any precautions I should take when administering Metronidazole to my dog?
Answer: Yes, you should always follow your veterinarian’s instructions when administering Metronidazole to your dog. Additionally, you should monitor your dog for any signs of side effects and report them to your veterinarian immediately. It is also important to avoid giving Metronidazole to pregnant or nursing dogs, as it can harm the developing fetuses or puppies.

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