Mefloquine for Malaria

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Mefloquine for Malaria


Generic Name

How It Works

Mefloquine prevents the development of malaria parasites in the blood. Mefloquine does not destroy the Plasmodium (P.) vivax or P. ovale parasites that may remain in the liver.

You take mefloquine as a tablet (orally).

To prevent malaria, you take mefloquine once, 1 to 3 weeks before you travel to an area where malaria is present, and then weekly while you are in the area, and weekly for 4 weeks after you leave.1

Mefloquine is used mainly to prevent malaria. If used to treat malaria, you may take 2 doses of mefloquine 6 to 12 hours apart.

Why It Is Used

People take mefloquine to prevent malaria and, in rare cases, to treat malaria. It is used to prevent malaria in areas where the strain of P. falciparum is resistant to chloroquine.

Do not take mefloquine if you have a history of irregular heartbeats (ventricular arrhythmias), abnormal sensitivity to this medicine, psychological conditions (such as depression), or seizures.

How Well It Works

One review of several different studies found that mefloquine is effective in preventing malaria.2

Medicine to prevent malaria is most effective if you take the correct dosage regularly. It's easier to remember if you take your weekly dosage with meals on the same day of the week each week, such as every Monday at lunch.

Medicine to prevent malaria destroys the malaria parasite when the parasite enters the bloodstream. Due to the long life cycle of the parasite, you need to take the medicine for 4 weeks after you leave the area where malaria is present.

Mefloquine is usually effective against all five species of Plasmodium and in regions where the chloroquine-resistant P. falciparum parasite is common.

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Call 911 or other emergency services right away if you have:

  • Trouble breathing.
  • Swelling of your face, lips, tongue, or throat.

Call your doctor right away if you develop:

Common side effects of mefloquine may include:

  • Nausea and diarrhea.
  • Dizziness.
  • Sleep disturbances (such as vivid dreams).
  • Headache.

You may be able to avoid the common side effects of mefloquine by taking the medicine with meals.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

If you have had a mental illness such as depression, mefloquine may not be right for you. In North America, people typically only use mefloquine to prevent malaria infection from chloroquine-resistant P. falciparum. When taking mefloquine to treat malaria infection, you need higher doses, and central nervous system side effects are common.

Some species of Plasmodium in Thailand, along the border areas with Cambodia and Myanmar (Burma), are resistant to mefloquine.

In some areas where malaria is common, travelers may also be advised to get a rabies vaccine if they are staying longer than 30 days, or if their professions expose them to special risks, such as those seen by biologists and veterinarians. If you are taking mefloquine, make sure the rabies vaccine is injected into your muscle (intramuscular). Mefloquine can reduce the effectiveness of this vaccine when it's injected into the skin (intradermal).

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

If you are pregnant, breast-feeding, or planning to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.



  1. Hill DR, et al. (2006). The practice of travel medicine: Guidelines by the Infectious Diseases Society of America. Clinical Infectious Diseases, 43(12): 1499–1539.
  2. Croft AM (2010). Malaria: Prevention in travellers, search date November 2009. Online version of Clinical Evidence (7).


ByHealthwise Staff
Primary Medical ReviewerKathleen Romito, MD - Family Medicine
Specialist Medical ReviewerW. David Colby IV, MSc, MD, FRCPC - Infectious Disease
Last RevisedMay 14, 2012

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