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Atovaquone

What is atovaquone?

Atovaquone (brand names: Mepron®, Malanil®, Wellvone®) is a drug used to treat infections caused by protozoa (single-celled organisms that cause disease). It is often combined with other drugs to treat specific infections.

In cats, it is used off-label in combination with azithromycin to treat cytauxzoonosis. In dogs, it is used off-label in combination with azithromycin to treat Babesia. It may be prescribed to treat other infections in dogs such as pneumocystosis.

Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.

How is atovaquone given?

This medication can take a few weeks before full effects are noted, but gradual improvements are usually noticeable.

What if I miss giving my pet the medication?

If you miss a dose, give it as soon as you remember, and then continue with the regular dosing schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.

Are there any potential side effects?

There are no known side effects from atovaquone in animals. However, reactions can occur. If any of the following signs develop, stop giving atovaquone and contact your veterinarian immediately:

Drug sensitivities can develop over time, with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.

Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This long-acting medication may last up to six weeks and may last longer in pets with kidney or liver disease.

Are there any risk factors for this medication?

DO NOT USE atovaquone in:

USE WITH CAUTION in:

Are there any drug interactions I should be aware of?

Several medications should be used with caution when given with atovaquone, including:

Be sure to tell your veterinarian about any medications (including vitamins, supplements or herbal therapies) that your pet is taking before starting any treatment.

Is any monitoring needed with this medication?

How do I store atovaquone?

What should I do in case of an emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet's weight and symptoms.

© Copyright 2025 LifeLearn Inc. Used and/or modified with permission under license. This content written by LifeLearn Animal Health (LifeLearn Inc.) is licensed to this practice for the personal use of our clients. Any copying, printing or further distribution is prohibited without the express written consent of LifeLearn. This content does not contain all available information for any referenced medications and has not been reviewed by the FDA Center for Veterinary Medicine, or Health Canada Veterinary Drugs Directorate. This content may help answer commonly asked questions, but is not a substitute for medical advice, or a proper consultation and/or clinical examination of your pet by a veterinarian. Please contact your veterinarian if you have any questions or concerns about your pet’s health. Last updated on Jun 27, 2025.

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