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Mefloquine for malaria prevention


Mefloquine tablets help to protect against malaria when travelling to a country where malaria occurs.

It is important that you start taking the tablets before you travel - the usual recommendation is to start the course of tablets 2-3 weeks before you travel. This allows the level of medicine in your body to become effective, and it also gives time to check for any side-effects before you travel. Continue to take a tablet on the same day of each week during your stay, and for four weeks after you return.

Mefloquine is only one of a number of measures that you need to take to reduce your risk of malaria. Others include wearing suitable clothing, using insect repellents and sleeping in screened rooms or beds.

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About mefloquine

Type of medicine

An antimalarial medicine

Used for

To prevent malaria (it is also used to treat malaria infection)

Also called


Available as


Mefloquine tablets help to protect you from malaria when you travel to areas where this can be a problem. Malaria is a serious infection. It is common in tropical countries such as parts of Africa, Asia, South and Central America, and the Middle East. Malaria is a disease which is passed on to humans by infected mosquitoes. A parasite called plasmodium lives inside the stomachs of infected female mosquitoes and is passed on to humans by a bite. Mefloquine works by killing the parasites passed into your body from the bites of the infected mosquitoes.

Because the pattern of malaria varies with the part of the world you are travelling to, as well as the season and the type of activity you have planned, you should always obtain the latest advice about malaria prevention from your doctor, pharmacist or travel organiser. A backpacking trip may well require different preventative measures against malaria to those needed for a business trip to a city.

Mefloquine tablets are not available on the NHS, although you will require a prescription from a doctor to obtain them. You will be given a private (non-NHS) prescription to take to your local pharmacy, and you will be asked to pay for the tablets when they are supplied.

Mefloquine can sometimes be given to treat malaria in people who have become infected. This leaflet does not contain information about this, but your doctor can give you more information if you have been prescribed it for this reason.

Before taking mefloquine

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking mefloquine it is important that your doctor or pharmacist knows:

  • If you are pregnant, trying for a baby or breastfeeding.

  • If you have epilepsy or have ever had fits (convulsions).

  • If you have a heart condition.

  • If you have ever had depression, severe anxiety, or any other mental health problem.

  • If you have any problems with the way your liver works, or with the way your kidneys work.

  • If you have had Blackwater fever (a complication of malaria infection).

  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.

  • If you have ever had an allergic reaction to a medicine. It is particularly important that you tell your doctor if you have ever had a bad reaction to a medicine called quinine.

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How to take mefloquine

  • Before you take mefloquine, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about mefloquine. It will also provide you with a full list of the side-effects which you may experience from taking it and what to do if you experience them.

  • Take the tablets exactly as your doctor tells you to. The dose to prevent malaria in an adult is one 250 mg tablet once a week. Your dose will be printed on the label of the pack to remind you. (If you have malaria and you are taking mefloquine to treat it, your dose will be different to this.) If you are giving mefloquine to a child, the dose prescribed will depend on the weight of your child. Check the label carefully to make sure you are giving the correct dose.

  • Start taking the course of tablets 2-3 weeks before you travel and continue to take them for four weeks after you return. Take the tablet on the same day of the week. If you develop any side-effects in the 2-3 weeks before you travel, speak with your doctor for further advice.

  • Swallow the tablet with a drink of water during a mealtime (or just after a snack). If you prefer, the tablet can be crushed and mixed with a little food, such as jam or honey, to make it easier to swallow.

  • If you forget to take a dose, take it as soon as you remember and then continue with your next dose on the usual day. Do not take two doses at the same time. You must complete the full course of tablets unless you are told otherwise by a doctor.

Getting the most from your treatment

  • These tablets will help prevent you from getting malaria, but it is also important that you take the following precautions against being bitten by mosquitoes:

    • Cover up bare areas of your arms and legs with long-sleeved, loose-fitting clothing, long trousers and socks. This is especially important if you are outside after sunset, as this is when mosquitoes feed.

    • Use an effective insect repellent spray on your clothing and any area of your skin which is bare. If you are also using a sunscreen, apply the sunscreen first and the insect repellent afterwards.

    • Spray the room with an insecticide each evening a couple of hours before you go to bed. Check your sleeping areas for mosquitoes - pay particular attention to furniture and areas under your bed where insects can hide.

    • If you are sleeping in an unscreened room, use a mosquito net impregnated with an insecticide.

  • It is possible that mefloquine may make you feel dizzy and affect your balance. These effects may continue for a while, even after you have stopped mefloquine. Make sure you know how you react before you drive and before you use machines or tools.

  • Your doctor will discuss with you the possibility of other unwanted side-effects. If you develop any changes in your moods, thoughts or behaviour, you should see your doctor before your next dose is due so that you can be given an alternative antimalarial medicine.

  • If you have been advised to have an oral vaccine to protect you against typhoid, you should arrange to have this at least three days before you start taking mefloquine. This is because mefloquine can stop the vaccine from working properly.

  • If you buy any other medicines to take, check with a pharmacist that they are safe to take alongside mefloquine.

  • If you feel ill or develop a high temperature (fever) or flu-like symptoms while you are travelling or within one year (especially if it is within three months) of returning home, you should see your doctor straightaway. This is important, even if you have taken your antimalarial tablets correctly.

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Can mefloquine cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with mefloquine. You will find a full list in the manufacturer's information leaflet supplied with your medicine. Speak with your doctor or pharmacist if any of the following continue or become troublesome.

Common mefloquine side-effects

What can I do if I experience this?

Feeling sick (nausea) or being sick (vomiting), stomach ache

Stick to simple meals - avoid spicy or rich foods


Drink plenty of water to replace any lost fluids

Feeling dizzy, loss of balance, problems with vision

Do not drive and do not use tools or machines. Symptoms may continue for some time even after you have stopped taking mefloquine


Drink plenty of water and ask your pharmacist to recommend a suitable painkiller. If the headaches continue, let your doctor know before you travel

Difficulties sleeping, itchy skin

If troublesome, speak with your doctor

Nightmares, feelings of panic, restlessness or anxiety, depression, confusion

Stop taking mefloquine tablets and speak with a doctor to obtain an alternative antimalarial

as soon as possible



be before your next dose would be due)

If you experience any other symptoms which you think may be due to the tablets, discuss them with your doctor or pharmacist who will be able to advise you further.

How to store mefloquine

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

MHRA - Reporting adverse reactions

Report suspected side effects to medicines, vaccines, e-cigarettes, medical device incidents, defective or falsified (fake) products to the Medicines and Healthcare products Regulatory Agency to ensure safe and effective use.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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