Mepron (Atovaquone) - Oral

What Is Mepron?

Mepron (atovaquone) is an orally administered medication used to prevent and treat Pneumocystis carinii pneumonia (PCP). PCP is a type of pneumonia likely to impact those with human immunodeficiency virus (HIV).

Specifically, Mepron works to prevent PCP in those who cannot tolerate trimethoprim-sulfamethoxazole (TMP-SMX; a drug used to treat urinary tract infections [UTIs]) or to treat PCP in those with mild-to-moderate PCP.

Mepron is an antimalarial approved for people 12 and older.

Mepron is classified as an antiprotozoal agent. Mepron works by halting the spread of certain types of protozoa (single-celled organisms that feed on organic matter) that can cause pneumonia.

The mechanism Mepron uses to fight infection is not entirely understood, but it prevents growth by inhibiting major processes that the fungus relies on for survival.

While also available as a generic product, Mepron is a brand-name medication that contains the active ingredient atovaquone. Mepron is administered as an oral suspension (a drug that is dissolved and mixed into a liquid).

Drug Facts

Generic Name: Atovaquone

Brand Name: Mepron 

Drug Availability: Prescription

Therapeutic Classification: Quinone antimicrobial

Available Generically: Yes

Controlled Substance: N/A

Administration Route: Oral

Active Ingredient: Atovaquone

Dosage Form: Oral suspension

What Is Mepron Used For?

The Food and Drug Administration (FDA) has approved Mepron for the prevention or treatment of Pneumocystis carinii pneumonia (PCP), which is now more commonly referred to as Pneumocystis jirovecii.

Mepron prevents PCP in those who cannot tolerate TMP-SMX or treats PCP in those with a current PCP diagnosis.

For context, TMP-SMX (often referred to as Bactrim), in addition to treating PCP, helps to treat middle ear infections, bronchitis, diarrhea, dysentery (a severe form of diarrhea), and UTIs.

PCP is most likely to affect those with HIV.

HIV-positive individuals possess a virus that attacks cells that help the body fight infection, making a person more susceptible to disease and opportunistic infections. It is spread by contact with certain bodily fluids.

Pertaining to the infection itself, PCP affects most people during childhood, but the majority of those impacted have an immune system strong enough to fight off the infection.

Finally, this fungus can incur shortness of breath, chest pain, a dry cough, diarrhea, and fatigue.

How to Take Mepron

When taking Mepron, the following instructions will guide you through safe consumption:

  • Mepron is usually taken either once or twice a day and should be taken with food to improve absorption.
  • Mepron is an oral suspension that you’ll take by mouth. It is yellow in color and has a citrus flavor. It will come either in a bottle that holds 210 milliliters and has a child-resistant cap or in individual foil pouches that each hold 5 milliliters of atovaquone.
  • If you’re using the large bottle, shake it gently before measuring and take your dose with an oral syringe or dosing cup.
  • If you have the foil pouches, open each one by folding along the dotted line and tearing open at the horizontal slit as directed by the arrow on the pouch.
  • Take the entire contents of the pouch by placing the medicine directly into your mouth or by putting it in a spoon or cup and then taking it. A typical dose will be either one or two full pouches.
  • Follow your prescribing instructions exactly. Do not abruptly stop your prescription without first consulting your healthcare provider.

Off-Label Uses

The use of Mepron is mostly limited to treating PCP.

However, a brand-name drug, Malarone, which is a combination of atovaquone and proguanil, is effective for treating and preventing malaria (a mosquito-borne disease caused by the bite of an infected mosquito).

How to Store Mepron

Whether you are given the large bottle of Mepron or the individual foil pouches, store the medicine at room temperature (59 to 77 degrees F). Do not refrigerate or freeze it.

Moreover, keep away from areas susceptible to high levels of moisture (e.g., the bathroom).

Keep Mepron packed in your carry-on luggage with the lid on tight so that pressure changes don’t cause leaks.

The TSA allows medically necessary liquids and supplies, so you don’t have to worry about carry-on liquid restrictions.

However, make sure to bring your prescription information and notify TSA personnel when you’re going through security that you have the drug with you.

How Long Does Mepron Take to Work?

The typical length of time you’ll take Mepron to treat PCP is 21 days. You will likely start seeing symptom improvement after a few days to a week. However, if you see no improvement in two weeks or your symptoms worsen, notify your healthcare provider as soon as possible.

What Are the Side Effects of Mepron?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects.

If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at or 1-800-FDA-1088.

Common Side Effects

If you notice any of the following side effects and believe they are growing in severity or do not go away promptly, you should notify your healthcare provider immediately:

Severe Side Effects

The severe side effects listed below were identified after Mepron was approved, rather than as part of clinical trials.

Specifically, these are reactions that were reported on a case-by-case basis, so how often, or in what percent of individuals they occur, is difficult to say.

Notify your healthcare provider right away if you notice these. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency.

Serious side effects and their symptoms can include the following:

Report Side Effects

Mepron may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Mepron Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For prevention of Pneumocystis jiroveci pneumonia (PCP):
    • For oral dosage form (suspension):
      • Adults and children 13 years of age and older—1500 milligrams (mg) or 10 milliliters (mL) once a day with food.
      • Children younger than 13 years of age—Use and dose must be determined by your doctor.
  • For treatment of Pneumocystis carinii pneumonia (PCP):
    • For oral dosage form (suspension):
      • Adults and children 13 years of age and older—750 milligrams (mg) or 5 milliliters (mL) two times a day with food for 21 days.
      • Children younger than 13 years of age—Use and dose must be determined by your doctor.
    • For oral dosage form (tablets):
      • Adults—750 milligrams (mg) taken with a meal three times a day for 21 days.
      • Children—Use and dose must be determined by your doctor.


Potential users should be aware of the following before beginning Mepron

In pregnancy: There isn’t enough data available from using Mepron in pregnant people to identify the risk of birth defects or miscarriage that it may cause.

In general, pregnant people who have HIV and get infected with PCP are at an increased risk of negative outcomes or maternal death compared to non-pregnant people.

In breastfeeding: The Centers for Disease Control and Prevention (CDC) recommends that parents infected with HIV not breastfeed to avoid the risk of passing HIV to their infants.

Moreover, it's not known whether Mepron is present in human milk or what effects it may have on the child receiving breast milk.

In children: The safety and effectiveness of using Mepron in children 12 and younger have not been established.

Missed Dose

If you forget a dose of Mepron, you can take it as soon as you remember. Just remember to take it with food.

If you are closer to your next dose than the dose you missed, go ahead and skip the missed dose and wait for your next scheduled one.

For example, if you take Mepron with breakfast and dinner at 7 a.m. and 6 p.m. and remember at 4 p.m. that you forgot your morning dose, skip it and take the next dose with dinner.

Overdose: What Happens If I Take Too Much Mepron?

If you take Mepron as directed, you shouldn’t be too concerned about using too much or overdosing.

If you do ingest too much Mepron, you may experience side effects like rash or blood disorders. There is no known antidote for Mepron.

Contact your healthcare provider as soon as possible if you think you have overdosed.

What Happens If I Overdose on Mepron?

If you think you or someone else may have overdosed on Mepron, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Mepron, call 911 immediately.


Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.

If your symptoms do not improve within a few days, or if they become worse, check with your doctor.

Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, vomiting, or yellow eyes or skin. These could be symptoms of a serious liver problem.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn't Take Mepron?

If any of the following apply to you, Mepron may not be your best drug choice.

  • If you have had any kind of hypersensitivity reaction to atovaquone in the past, like swelling, hives, or throat tightness.
  • There is a chance of significantly lower drug absorption and possible treatment failure if you cannot take Mepron with food or if you have gastrointestinal disorders that limit how much oral medicine you can absorb. Possible examples include inflammatory bowel disease (IBD), Celiac disease, irritable bowel syndrome (IBS), and short bowel syndrome (SBS).
  • Make sure your healthcare provider is aware if you have the severe hepatic (liver) disease, as atovaquone may worsen liver conditions.

What Other Medications Interact With Mepron?

The following are drugs that may interact with atovaquone and should be used with caution or may require dose adjustments:

  • Rifampin and Aemcolo (rifamycin) are antibiotics that can lower the concentration of Mepron in your body if either of them is taken while on atovaquone, causing it not to work as well—taking these antibiotics while on atovaquone is not recommended.
  • Tetracycline is another antibiotic that can lower Mepron concentration, so the Mepron dose may need to be increased to compensate for this interaction.
  • Raglan (metoclopramide) may reduce how much atovaquone gets absorbed. Raglan should only be used if another nausea medicine is unavailable.
  • Crixivan (indinavir) is an HIV medication that may be less effective if it’s taken with Mepron. Be cautious of this interaction since it’s very important that both of these drugs work as they are supposed to. Consider speaking with your healthcare provider about changing one of the drugs.

What Medications Are Similar?

The following are medicines that are also in the antiprotozoal drug class and are used to treat a variety of parasitic infections:

  • Alinia (nitazoxanide) is used to treat diarrhea caused by some parasites including Giardia or Cryptosporidium.
  • Nebupent (pentamidine) is also used for PCP. Nebupent is available as an injection or as a liquid inhaled via a nebulizer machine.
  • Lampit (nifurtimox) is an antiprotozoal used to treat Chagas disease caused by the parasite Trypanosoma cruzi in children younger than 18.
  • Fexinidazole is a newer antiprotozoal drug indicated for Trypanosoma brucei gambiense sleeping sickness, a parasitic disease transmitted by the bite of an infected tsetse fly that is prevalent in sub-Saharan Africa.

This list is not a list of drugs recommended to take with Mepron. In fact, you should not take these drugs together. Ask your pharmacist or a healthcare provider if you have questions.

Frequently Asked Questions

  • What is Mepron used for?

    Mepron is used to treat or prevent Pneumocystis carinii pneumonia (PCP), which is now more commonly referred to as Pneumocystis jirovecii pneumonia.

    PCP is an opportunistic infection that most often causes symptoms in HIV-positive individuals.

  • What are the side effects of Mepron?

    The most common side effects of Mepron include rash, nausea, vomiting, diarrhea, headache, insomnia, or trouble sleeping.

    Mepron side effects that are potentially more serious, but whose frequency is unknown, include blood disorders, hypersensitivity reactions, and liver or kidney injury.

  • How long will it take for Mepron to work?

    The typical length of time you’ll take Mepron to treat PCP is about three weeks. You will likely start seeing symptom improvement after a few days to a week.

    However, if you see no improvement in two weeks or your symptoms worsen, notify your healthcare provider.

How Can I Stay Healthy While Taking Mepron?

While you’re fighting a PCP infection, it’s essential to stay as healthy as you can in all the ways you can control, including maintaining proper nutrition, staying hydrated, getting plenty of decent rest, and avoiding others who are sick.

It's also important to note that coughing is a common symptom of PCP. This is one mechanism your body uses to help clear the infection from your lungs.

If you can, try to use cough medicine only at night when you’re trying to get a full night of sleep. If it is otherwise disruptive to your rest or is causing chest pain, talk to your healthcare provider about what cough medicine regimen they recommend for you.

Make sure to get some protein with each meal to help your body repair damage.

Do whatever you can to prioritize your mental health as well, since stress, anxiety, and depression can all weaken your immune system further.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Sara Hoffman, PharmD
Sara is a clinical pharmacist that believes everyone should understand their medications, and aims to achieve this through her writing.