This medicine contains the active ingredient mefloquine, which is a type of medicine called an antimalarial. It is used in both the prevention and treatment of malaria.

Lariam (Mefloquine) 250mg
1 Tablets
Lariam (Mefloquine) 250mg
8 Tablets

Malaria is a potentially fatal disease caused by various types of parasites known as Plasmodium. Plasmodium are carried by mosquitoes and injected into the bloodstream during a bite from an infected mosquito. Once inside the blood the parasites travel to the liver, where they multiply. The parasites are then released back into the bloodstream where they invade the red blood cells and multiply again. An actual attack of malaria develops when the red blood cells burst, releasing a mass of parasites into the bloodstream. The attacks do not begin until a sufficient number of blood cells have been infected with parasites.

Mefloquine works by attacking the parasites once they have entered the red blood cells. It kills the parasites and prevents them from multiplying further.

It is not fully understood how mefloquine kills the parasites, but it is thought to work by blocking the action of a chemical that the parasites produce to protect themselves once inside the red blood cells. The parasites inside the red blood cells digest the oxygen carrying pigment haemoglobin that is found in these cells. This divides the haemoglobin into two parts; haem and globin, and the haem part is toxic to the malaria parasite. To prevent itself from being damaged by haem, the malaria parasites produce a chemical that converts haem into a compound that is not toxic to them. Mefloquine blocks the action of this chemical. This causes the levels of the toxic haem to rise, thus killing the malaria parasites.

Mefloquine is one of the options for preventing malaria in areas of the world where there is a high risk of falciparum malaria that is resistant to chloroquine. It is important to check with your pharmacist which medicines are currently recommended to prevent malaria in the country you are travelling to.

If mefloquine is recommended it should be started at least one week but preferably two to three weeks before travel to the malarious region. It should then be taken throughout the stay so that if you are bitten by an infected mosquito, there will be medicine in your blood to prevent malaria developing. Mefloquine should be continued for a further four weeks after leaving the malarious area so that there is still medicine in the blood to kill any remaining parasites released from the liver into the red blood cells during this time.

Higher doses than those used for preventing malaria are used to treat malaria infection.

What is it used for?

Prevention of malaria
Treatment of malaria


In some people mefloquine can cause psychiatric side effects such as mood or behaviour changes, anxiety, depression, feelings of persecution, crying, aggression, forgetfulness, agitation, confusion or hallucinations. If affected you should stop taking this medicine and consult a doctor immediately. In 75 per cent of cases such side effects appear by the third dose if they are going to affect you. For this reason, if taking mefloquine to prevent malaria it is recommended you start taking it 3 weeks before travel, so that if affected you can be prescribed an alternative preventative medicine.
This medicine may cause various side effects that could impair your mental or physical ability to safely drive or operate machinery. You should be aware of how you react to this medicine before driving or operating machinery.
To prevent malaria it is important that you take this medicine regularly and try not to forget a dose. You should still take precautions to avoid being bitten by mosquitos, such as using mosquito repellants and sleeping under mosquito nets. This is particularly important if you have vomiting or diarrhoea. If you fall ill within one year of your return, and especially if within three months of your return, you should consult your doctor immediately and let him know that you have visited a country where malaria is endemic.
To prevent malaria this medicine should be taken once weekly, on the same day each week, as directed by your doctor. It should be started at least one week, but preferably two to three weeks before travelling to the malarious area (see above). It should be taken regularly throughout the stay and continued for four weeks after leaving the malarious area.
This medicine is not recommended for children aged under three months or weighing less than five kilograms.
Women of child-bearing age who are taking this medicine for malaria prevention or treatment are advised to use effective contraception to prevent pregnancy, both during treatment and for three months after stopping treatment. This is because the safety of the medicine during pregnancy has not been established. Seek further medical advice from your doctor.

Use with caution in

Decreased kidney function
Defects of the heart’s electrical message pathways, causing irregular heartbeats (heart conduction defects)

Not to be used in

Allergy to quinine
People with a history of convulsions, eg epilepsy, if used for malaria prevention
People with a history of psychiatric illness (including depression) if used for malaria prevention
People with severely decreased liver function, if used for malaria prevention

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.

If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and Breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

The safety of this medicine during pregnancy has not been established. It is not recommended for use during pregnancy, unless considered essential by your doctor for malaria treatment. It should not be used for malaria prevention in women who are pregnant. Non-pregnant women taking this medicine for malaria prevention or treatment are advised to use effective contraception to prevent pregnancy, both during treatment and for three months after stopping treatment. Seek further medical advice from your doctor.
This medicine may pass into breast milk, therefore mothers taking this medicine must not breastfeed. Discuss with your doctor.

Label warnings

Take this medication with or after food.
This medication is to be swallowed whole, not chewed.
This medication is to be taken with plenty of water.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

Disturbed sleep
Shaking, usually of the hands (tremor)
Visual disturbances
Balance problems involving the inner ear (vertigo)
Pins and needles (paraesthesia)
Awareness of your heartbeat (palpitations)
Changes in blood pressure
Sleepiness (somnolence)
Weakness or loss of strength (asthenia)
Chest pain
Skin reactions such as rash and itch
Disturbances of the gut such as nausea, vomiting, diarrhoea or abdominal pain
Psychiatric reactions such as depression, mood changes, anxiety, confusion, hallucinations, panic attacks, restlessness, forgetfulness, psychosis, paranoia, emotional instability, aggression and agitation (see warnings above)
Fits (convulsions)

The side effects listed above may not include all of the side effects reported by the drug’s manufacturer.

For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.
How can this medicine affect other medicines?

There may be an increased risk of irregular heart beats (arrhythmias) if mefloquine is taken with the following medicines:
– halofantrine (must not be taken at the same time as or following treatment with mefloquine)
– quinidine
– medicines for irregular heart beats (antiarrhythmics)
– beta-blockers eg propranolol
– calcium channel blockers eg verapamil
– antihistamines, eg terfenadine
– tricyclic antidepressants eg amitriptyline
– antipsychotics, eg chlorpromazine, pimozide, thioridazine.

There may be an increased risk of convulsions if mefloquine is taken with the following medicines:
– antiepileptics eg phenytoin, carbamazepine, valproate
– chloroquine
– quinine
– quinidine.

Mefloquine may weaken the effect of the oral typhoid vaccine. If the oral typhoid vaccine is needed the course should be completed preferably at least three days before the first dose of mefloquine is taken. In urgent cases where mefloquine is already being taken the vaccination should be arranged so that a mefloquine dose is not taken for at least 12 hours before or after a dose of the vaccine.