Skip to Content


Generic Name: Mefloquine (ME floe kwin)

Medically reviewed by Last updated on May 20, 2020.


  • This medicine can cause dizziness, loss of balance, ringing in the ears, anxiety, paranoia, low mood (depression), seizures, not thinking clearly or with logic, mood changes, changes in how you act, or hallucinations. These side effects may last for a few months or can be long-lasting and not go away even after the drug is stopped. Do not take mefloquine to prevent malaria if you have mental or mood problems. Call your doctor right away if you have any of these side effects.

Uses of Mefloquine:

  • It is used to treat or prevent malaria.

What do I need to tell my doctor BEFORE I take Mefloquine?

  • If you have an allergy to mefloquine or any other part of mefloquine.
  • If you have an allergy to quinidine or quinine.
  • If you are allergic to mefloquine; any part of mefloquine; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
  • If you have ever had any of these health problems: Anxiety, low mood (depression), psychosis, any other mood problem, or seizures.
  • If you are taking any of these drugs: Chloroquine, quinidine, or quinine.
  • If you are taking any of these drugs: Halofantrine or ketoconazole. Do not take these drugs within 15 weeks of your last dose of mefloquine.
  • If you have recently had a live vaccine

This is not a list of all drugs or health problems that interact with mefloquine.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take mefloquine with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take Mefloquine?

For all uses of mefloquine:

  • Tell all of your health care providers that you take mefloquine. This includes your doctors, nurses, pharmacists, and dentists.
  • Avoid driving and doing other tasks or actions that call for you to be alert until you see how mefloquine affects you.
  • Have patient safety card with you at all times.
  • Have your blood work checked if you are on mefloquine for a long time. Talk with your doctor.
  • Have an eye exam as you have been told by your doctor.
  • This medicine may raise the chance of seizures in some people, including people who have had seizures in the past. Talk to your doctor to see if you have a greater chance of seizures while taking mefloquine.
  • Use with care in children. Talk with the doctor.
  • Use birth control to prevent pregnancy while taking mefloquine and for 3 months after the last dose.
  • If you get pregnant while taking mefloquine or within 3 months after your last dose, call your doctor right away.
  • Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.

Preventing malaria:

  • Other measures are needed along with mefloquine including using screens, bed netting, insect repellent (10% to 35% DEET), and permethrin spray on clothing and nets. Avoid spraying most insect repellents on children. Lower evening and night-time outdoor activity.
  • If you have a fever after leaving a malaria area, call your doctor right away.
  • If you are a pregnant woman and traveling to a malaria infested place, talk to your doctor about the risks first.

How is this medicine (Mefloquine) best taken?

Use mefloquine as ordered by your doctor. Read all information given to you. Follow all instructions closely.

For all uses of mefloquine:

  • Take mefloquine with the largest meal of the day.
  • Do not take on an empty stomach.
  • Take with a full glass of water.
  • Tablet can be crushed and mixed with water, milk, or other liquid.
  • Keep using mefloquine as you have been told by your doctor or other health care provider, even if you feel well.
  • Talk with your doctor to find out what to do if you throw up after taking a dose of mefloquine.

Preventing malaria:

  • Use as you have been told to prevent malaria.
  • If using to prevent malaria, start mefloquine before traveling to the high risk place.

What do I do if I miss a dose?

Treating malaria:

  • Most of the time, 1 dose of mefloquine is needed. If you miss the dose, take it as soon as you think about it with food. If you need to take more than 1 dose of mefloquine, follow what your doctor has told you to do.

Preventing malaria:

  • Take a missed dose as soon as you think about it.
  • If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.
  • If you miss a dose before leaving for your trip, call your doctor to find out what to do.

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
  • Chest pain or pressure or a fast heartbeat.
  • Slow heartbeat.
  • A heartbeat that does not feel normal.
  • Very bad dizziness or passing out.
  • Change in eyesight, eye pain, or very bad eye irritation.
  • Not able to sleep.
  • Restlessness.
  • Some people taking mefloquine have committed suicide. It is not known if mefloquine was the reason for the suicides. Tell your doctor if you have thoughts of suicide.
  • Unsafe blood cell count problems have happened, like aplastic anemia and a type of low white blood cell count. Tell your doctor right away if you feel very tired or weak, or have a fever, chills, shortness of breath, any unexplained bruising or bleeding, or purple "splotches" on your skin.

What are some other side effects of Mefloquine?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Headache.
  • Upset stomach or throwing up.
  • Belly pain.
  • Diarrhea.
  • Not hungry.
  • Muscle pain.
  • Feeling tired or weak.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at

If OVERDOSE is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

How do I store and/or throw out Mefloquine?

  • Store at room temperature.
  • Store in a dry place. Do not store in a bathroom.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.

Consumer information use

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else's drugs.
  • This medicine comes with an extra patient fact sheet called a Medication Guide. Read it with care. Read it again each time mefloquine is refilled. If you have any questions about mefloquine, please talk with the doctor, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.