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Drug Class: Commonly Known As: Category:
Antimalarial Adult, Children

Mefloquine - Side Effects, Precautions, and Contraindications

What side effects can Mefloquine cause?

  • ​You may experience nausea, vomiting and abdominal pain.
    • Take the medication after food to minimise gastric side effects.
    • If you vomit within 30 minutes of taking the medication, take the medication again.
    • If you vomit 30 to 60 minutes after taking the medication, take half the dose of the medication again
  • You may experience headache and insomnia.
    • You should continue taking the medication unless you are unable to tolerate the side effects.

Most side effects from this medication usually occur before the second dose.

Rare but serious side effects include:

  • Vivid dreams
  • Dizziness
  • Loss of balance
  • Ringing in the ears
  • Acute anxiety, depression, restlessness and confusion
  • Liver problems
    • Symptoms include dark urine or light coloured stools, nausea, vomiting, loss of appetite, stomach pain, yellowing of your eyes or skin.
  • Fast or abnormal heartbeats
  • Changes in your eyesight or eye pain
  • Drug allergy (symptoms include one or more of the following)
    • Swollen face/eyes/lips/tongue.
    • Difficulty in breathing.
    • Itchy skin rashes over your whole body.

Some side effects of Mefloquine may last for a few months or can last longer and not go away even after the drug is stopped.

If you experience any of the above symptoms, stop taking Mefloquine and inform your doctor right away.  You may require a different medication to prevent malaria.

Before taking Mefloquine, what precautions must I follow?

​Inform your healthcare professional if:

  • You are allergic to this medication or any other ingredients of this medication.
  • You have an allergy to quinine, quinidine or chloroquine.
  • You are pregnant or breast-feeding. Avoid pregnancy and use contraceptives while taking this medication and for 3 months after the last dose.
  • You are taking any other medications, including supplements, traditional medications and herbal remedies.
  • You have a history of seizures (epilepsy or convulsions) or psychiatric disorders (including depression, generalized anxiety disorders, psychosis and schizophrenia) or heart conduction abnormalities.
  • You are taking Mefloquine for a year or longer.

Avoid activities that require a high degree of alertness, sense of balance or performance of skilled tasks until you know how Mefloquine affects you. You may feel dizzy or lose your balance. This could happen for months or years after you stop taking Mefloquine and it can be permanent in rare cases.

What food or medicine must I avoid when I take Mefloquine?

  • ​Mefloquine may interact with alcohol and increase your risk of experiencing certain side-effects such as dizziness or drowsiness. Limit your alcohol intake while taking Mefloquine and do not drink alcohol on the day you take your Mefloquine tablet.
  • Check with your healthcare professional if you had or intend to receive vaccines. Mefloquine might affect how well the vaccines work on you.

Inform your pharmacist or doctor if you are taking any of the medications below:

  • Halofantrine (used to treat malaria)
  • Ketoconazole (used for fungal infections)
  • Quinine (Qualaquin) or Quinidine (used to treat malaria or irregular heart beat)
  • Chloroquine (Aralen) (used to treat malaria)

This is not a complete list of all possible drug interactions with this medication. Check with your healthcare professional if you are unsure.

Mefloquine - Additional Information

To prevent malaria, you may protect yourself against mosquito bites by

  • Wearing long-sleeved clothing and long trousers between sunset and sunrise.
  • Applying insect repellent containing more than 20% DEET (N-Diethyl-meta-toluamide) for adults or 10% and less DEET for children on exposed skin. DEET is a common active ingredient in mosquito repellents.
  • Using mosquito coils in the room at night.
  • Sleep with mosquito nets around your bed, with the net edges tucked under the bed or sleep in a screened room.
  • Spray insecticide where mosquitos may rest. Mosquito larvae survive well in clear, slow-flowing streams.
  • Avoid going to an area where malaria is common.

Following these guidelines and medication does not mean that you will not get malaria. If you have a fever or experience chills between 1 week and up to 1 year after your return, you should seek medical attention. Inform the doctor that you have been to a country where malaria is common. Malaria can be effectively treated if discovered early. A delay in treatment may result in serious health problems.



  • Updated on Monday, September 30, 2019
  • Article contributed by PSS National Medication Information Workgroup PSS National Medication Information Workgroup

    The information provided is not intended as medical advice. Terms of use. Information provided by SingHealth

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