Metronidazole (Flagyl) is a nitroimidazole antibiotic that’s FDA-approved in humans. Veterinarians also prescribe this medication off-label to treat certain infections in dogs and cats. For pets, metronidazole is given by mouth, typically twice daily. Treatment usually lasts 5 to 7 days. Metronidazole comes as a tablet or capsule.Your veterinarian might recommend for you to go to a compounding pharmacy to have it made into a liquid that’s easier for your pet to take. Some side effects of this medication that your pet might have include gagging, drooling, and reddish-brown urine.
Metronidazole is a nitroimidazole antibiotic. It kills bacteria and parasites by damaging their genetic material. Metronidazole can also help lower inflammation (swelling and pain) in the gut that’s caused by the infection.
The following side effects might get better over time as your pet gets used to the medication. Let your veterinarian know immediately if your pet continues to experience these symptoms or if they worsen over time.
Contact your veterinarian immediately if your pet experiences any of the following.
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
More common
Agitation
back pain
blindness
blurred vision
burning, numbness, tingling, or painful sensations in the hands or feet
changes in speech patterns
confusion
decreased vision
dizziness
drowsiness
headache
irritability
lack of coordination
seeing or hearing things that are not there
seizures
shakiness and unsteady walk
slurred speech
stiff neck or back
trouble speaking
unsteadiness, trembling, or other problems with muscle control or coordination
unusual tiredness or weakness
vomiting
weakness in the arms, hands, legs, or feet
Less common
Black, tarry stools
blood in the urine
body aches or pain
burning while urinating
chills
clumsiness or unsteadiness
difficulty with breathing
ear congestion
fainting
feeling of pelvic pressure
frequent or painful urination
irregular heartbeat
loss of voice
pinpoint red spots on the skin
skin rash, hives, redness, itching
stomach and back pain (severe)
unusual bleeding or bruising
vaginal irritation, discharge, or dryness not present before taking the medicine
Rare
Bleeding gums
dark urine
fast heartbeat
indigestion
loss of appetite
painful or difficult urination
pains in the stomach, side, or abdomen, possibly radiating to the back
sores, ulcers, or white spots on the lips or in the mouth
swollen glands
yellow eyes or skin
Incidence not known
Blistering, peeling, or loosening of the skin
bloody or cloudy urine
burning while urinating
continuing diarrhea
continuing stomach pain
feeling of warmth
increased volume of pale, dilute urine
joint or muscle pain
loss of bladder control
red skin lesions, often with a purple center
red, irritated eyes
redness of the face, neck, arms, and occasionally, upper chest
redness of the skin
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
More common
Dizziness or lightheadedness
feeling of constant movement of self or surroundings
sensation of spinning
stomach cramps
trouble sleeping
Rare
Change in taste sensation
congestion
pain or tenderness around the eyes and cheekbones
tender, swollen glands in the neck
trouble with swallowing
unpleasant or sharp metallic taste
voice changes
Incidence not known
Decreased interest in sexual intercourse
inability to have or keep an erection
loss in sexual ability, desire, drive, or performance
painful sexual intercourse
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Once you start giving your dog metronidazole, the medication will get absorbed within a few hours. But you might not notice an improvement in your dog’s symptoms, such as fewer loose stools, until a few days later. It’s important that your dog finishes the full course of metronidazole prescribed by the veterinarian, even if your dog seems to feel better before then. Stopping an antibiotic too early can cause the infection to come back and become more difficult to treat.
Your veterinarian will let you know how long to give your dog metronidazole. Typically, a treatment course lasts 5 to 7 days. But this can differ from dog to dog depending on what type of infection they have, how serious it is, and whether or not they’re experiencing serious side effects from metronidazole. Talk with your veterinarian if you have concerns about how long your dog should take this medication.
You might be able to give metronidazole to your dog without food, depending on the form of the medication. In general, metronidazole tablets and capsules are bitter, so it’s recommended that you give the pills to your dog with a tasty treat to mask the taste. But you might not have this problem if your veterinarian gives you a prescription for a compounded liquid solution. The compounding pharmacist typically adds a flavoring agent to make this liquid solution taste better for your dog. In addition, some dogs feel nauseous from taking metronidazole, so giving this medication with food can help. Ask your veterinarian about the best way to give metronidazole to your dog.
Metronidazole pills taste bitter, so your dog might not want to take them. One way to help is by hiding the pill in foods or treats. You can also buy pill pockets from local pet stores. Another tip is to place the pill at the back of your dog’s throat, gently close their mouth, and stroke their throat to help them swallow. If pills are too hard to give, ask your vet about the liquid version (Ayradia) or having it compounded into a flavored liquid. Some dogs find liquids easier to take.
Metronidazole tablets and capsules taste bitter, so your cat might not take them easily. You can try hiding the pill in a pill pocket available at pet stores. If your cat refuses pills, ask your vet if metronidazole can be made into a flavored liquid by a compounding pharmacy. Pharmacists often add flavorings to compounded pet medications to make them taste better. Also try to speak calmly to lessen the stress your cat might be feeling. Sometimes, it helps to wrap your cat in a blanket to soothe them. If needed, ask your veterinarian for suggestions about the best way to give metronidazole to your cat.
Metronidazole isn’t known to cause constipation in cats. It’s more likely to cause diarrhea as a side effect because this antibiotic affects the balance of bacteria in your cat’s gut. If your cat experiences gut-related problems after starting metronidazole, talk with your veterinarian; they can let you know if your cat needs more medical attention.
Metronidazole can cause some serious health issues. This risk might be even higher for certain pets. If this worries you, talk to your veterinarian about other options.
If the dose of metronidazole is too high for your dog or cat, it can cause serious neurological side effects, including movement problems, tremors, seizures. The risk is higher for pets that already have seizure conditions or are taking seizure medications. Let your veterinarian know right away if you notice these symptoms in your pet so they can let you know about the next steps.
Based on how metronidazole works in the body and data from human studies, there’s a risk that it can interact with certain medications, including cimetidine (Tagamet), warfarin (Coumadin), and certain seizure medications. Let your veterinarian know about all the medications your pet is taking before starting metronidazole. Your veterinarian can help you check for possible interactions with metronidazole to keep your pet safe.
Metronidazole shouldn’t be given to dogs and cats that are pregnant or nursing. Though studies are limited, there’s a risk that this medication can cause serious harm during pregnancy. Metronidazole can also pass into mother’s milk and cause harm to nursing puppies or kittens. If your cat or dog is pregnant or nursing, let your veterinarian know. They can talk with you about options for your pet.
Let your veterinarian know if your dog or cat has liver or kidney problems. Metronidazole is mainly processed through the liver, and cleared from the body through both the liver and kidney. If your pet’s liver or kidney isn’t working well, they’re more likely to experience side effects. In some cases, the veterinarian will consider giving your pet a lower dose of metronidazole.
Though rare, pets that take metronidazole might experience a serious skin reaction called cutaneous vasculitis. This condition is caused by inflammation of the blood vessels. Get medical help right away if you notice symptoms of this skin reaction in your pet, such as cuts and bruises on the skin, purple or red spots on the skin, and fever. They might need more medical attention.
| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 59ml of 0.75% | 1 bottle | $55.54 | $55.54 |
| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 375mg | 14 capsules | $55.32 | $3.95 |
| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 55g of 1% | 1 pump | $38.28 | $38.28 |
| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 70g of 0.75% gel | 1 package | $22.53 | $22.53 |
| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 250mg | 30 tablets | $6.67 | $0.22 |
| 500mg | 14 tablets | $8.62 | $0.62 |
| 125mg | 14 tablets | $192.05 | $13.72 |
| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 45g of 0.75% | 1 tube | $22.71 | $22.71 |
Your veterinarian generally determines the dose of metronidazole for your cat or dog based on their body weight. But the dose can differ depending on other factors, such as your pet’s health condition or the type of infection the veterinarian thinks your pet has.
An example of possible dosing:
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.