Information on Mefloquine (Lariam®)

You will be spending part of your trip in an area where chloroquine-resistant malaria is widespread. Malaria is an important cause of disease and death abroad. It is a blood infection caused by a parasite called Plasmodium, which is transmitted by a mosquito bite.

Malaria can be prevented by taking medication regularly. However, since no drug is 100% effective, it is important to protect yourself against mosquito bites: use an insect repellent containing DEET, sleep under mosquito netting (preferably impregnated with permethrin), avoid perfumes, wear pale colored clothes that cover most of the body, and avoid going out in the evenings and at night. These measures are just as important as taking medicines.

Mefloquine (Lariam®) is recommended at the following dosage:


  • 1 tablet (250 mg) per week


  • 10-19 kg : 1/4 tablet per week
  • 20-29 kg : 1/2 tablet per week
  • 30-45 kg : 3/4 tablet per week
  • ≥ 46 kg : adult dose

Start taking the medication at least 3 weeks before departure and continue preventive treatment during your trip and for 4 weeks after leaving the region where malaria can be transmitted. Always take mefloquine on the same day of the week, after a meal, with a large glass of water or other liquid. Avoid excessive use of alcohol for the whole period during which you are taking this medication.

Side effects

Most travelers have no side effects. Occasionally, stomach aches, nausea, dizziness, feelings of anxiety, vertigo, or insomnia can occur. These reactions are usually minor and tend to be temporary; they disappear when medication is stopped. Adverse reactions can be lessened by splitting the dose in two smaller ones and taking one every 3 or 4 days (for example, ½ tablet on Monday and ½ tablet on Thursday).

Side effects such as vertigo and panic attacks can occur in less than 1 person in 100. More serious reactions such as depression, hallucinations, confusion, or convulsions occur very rarely (1 person in 6,000 to 13,000). All these side effects disappear when medication is stopped.

WARNING: stop taking the medication and consult your doctor if you


This medication may sometimes cause coordination problems: exercise caution if you are operating a vehicle or if you require fine motor coordination.

In case of fever

Despite taking preventive medication, fever that occurs when traveling or in the months after your return may be a sign of malaria. See a doctor immediately and tell him or her about your recent travel to a tropical area.

In case of fever, you should avoid taking halofantrin (Halfan) and Lumefantrin (one of the two components of CoArtem® and Riamet®) if you already take mefloquine, because the combination of those drugs may cause cardiac problems.


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