Antimalarial Drugs: Malaria Causes, Treatment and Prevention

Antimalarial drugs are prescription medicines that travellers take before, during and after a trip to lower their chance of catching malaria, a serious illness spread by mosquitoes in parts of Africa, Asia, the Pacific and South America. No tablet protects completely, so they work alongside avoiding bites. This guide explains how malaria is caught, the main kinds of prevention, who needs them, and the fever after travel that always needs a doctor.

Key takeaways

• Preventive medicine lowers your chance of malaria but cannot remove it, so avoiding bites matters just as much.
• The right choice depends on where you are going, for how long, your health and anything else you take.
• Start before you leave and keep going after you come home, for seven days or four weeks depending on the tablet.
• A fever in the year after visiting a malaria area needs a doctor the same day; confusion, drowsiness or trouble breathing needs 000.

Malaria, the Infection Antimalarial Drugs Help Prevent

Malaria is an infection of the blood caused by Plasmodium parasites, which mosquitoes pick up from one person's blood and pass to the next when they bite. Five kinds infect people, and falciparum is the most dangerous, as it can become life threatening within a day or two of the first fever. Australia has been free of local malaria since 1981, so almost every case seen here is in a traveller who has come home, which is why preventive medicine is advised for many overseas trips.

Preventive medicine stops the parasite multiplying in the blood, but mostly cannot clear the resting liver stage of vivax and ovale, so these can still appear months after you get home.

Symptoms of Malaria After Travel

The symptoms of malaria are fever, chills and sweats, often with a headache, aching muscles, tiredness, nausea, vomiting or diarrhoea, so it is easily mistaken for flu. They usually start one to four weeks after the infecting bite, but some types appear months later, so a fever up to a year after you return still counts.

Signs of severe malaria are confusion, drowsiness, a seizure, trouble breathing, yellow skin or eyes and very dark urine: call 000. Taking antimalarial drugs does not rule malaria out, so if you become unwell with a fever during or after a trip, see a doctor in person the same day, say where you have travelled, and ask for the blood test that checks for it. Keep taking your medication until the doctor tells you otherwise.

How the Malaria Parasite Spreads Through Mosquito Bites

Malaria spreads through the bite of an infected female Anopheles mosquito, which mostly feeds between dusk and dawn. The parasites travel first to the liver, where they multiply quietly for a week or more, then burst into the blood and invade red blood cells, which is when the fever starts. Transmission is highest in rural areas, during and after the wet season, and on overnight stays near water.

It does not pass between people through touch or coughing, though it can rarely spread through a blood transfusion or from mother to baby. Antimalarial drugs act on the parasites once they are in your body, so they are taken before the first bite and for weeks after your last exposure.

Types of Antimalarial Drugs for Travellers

Three antimalarial drugs, often called anti-malaria meds, are commonly used by Australian travellers for prevention, and each preventive medication is taken on its own schedule. Doxycycline is a daily tablet started a day or two before you enter a malaria area and continued for four weeks after you leave. A combination of atovaquone with proguanil is also daily, started a day or two before and continued for seven days after. Mefloquine is a weekly tablet, started two to three weeks before travel and continued for four weeks after.

Older options such as chloroquine are now rarely used, because the parasite has become resistant to chloroquine in most malaria areas. All of these are only available on prescription in Australia, none works perfectly, and each has side effects a doctor weighs with you.

How a Malaria Infection Is Treated

Malaria is treated as a medical emergency, because falciparum malaria can become severe within hours. The diagnosis needs a blood test, either a blood film or a rapid test, done the same day, usually at a hospital emergency department.

Severe malaria is treated in hospital with medicine given into a vein, while milder cases are usually treated with a short course of combination tablets, often with a stay in hospital at first. Treatment uses a different dose and often different drugs from prevention, so never use your own supply to treat yourself. Vivax and ovale infections may also need a second medicine to clear the parasites resting in the liver, after a blood test checks it is safe for you.

Travellers Suitable for Preventive Malaria Medicine

Preventive medicine is recommended for most stays in areas where malaria is common, such as sub-Saharan Africa, Papua New Guinea and the Solomon Islands, and for some rural parts of Asia and South America. Many cities and resort areas in Asia carry little or no malaria risk, so the advice depends on your exact route. Malaria prevention also matters for people visiting family in their country of birth, who often stay longer and are more likely to skip it.

Whether a medicine is suitable for you, and which one, depends on your destination and season, how long you will stay, your age and health, whether you are pregnant, your regular medication and any side effects you have had before. Doxycycline makes skin burn more easily in the sun; mefloquine is not used by people with depression, anxiety, another mental health condition or epilepsy; and the combination is not used with severe kidney disease. Long stays can suit a weekly tablet and short trips one that stops a week after you return, and costs differ. Mention any intolerance too, including lactose, which a pharmacist can check for.

Mosquito Bite Prevention With Repellent, Clothing and Nets

Bite prevention matters as much as any tablet, because no medicine is fully effective. Use a repellent containing DEET, picaridin or oil of lemon eucalyptus on exposed skin, reapply it as the label says, and put sunscreen on first. From dusk to dawn wear long, loose, light coloured sleeves and trousers, ideally treated with permethrin, and stay in screened or air conditioned rooms.

Where rooms are open to the air, sleep under insecticide treated mosquito nets, tucked in and checked for holes, and pack your own if unsure the nets will be there. Malaria prevention rests on four things working together: knowing your risk, avoiding bites, taking your medication exactly as directed, and getting a fast diagnosis for any fever.

Travelling to a Malaria Area During Pregnancy

Malaria is more dangerous during pregnancy, for both mother and baby, raising the chance of severe illness, miscarriage, premature birth and low birth weight, so the usual advice is to delay travel to a malaria area until after the birth if you can. Pregnant women also attract more mosquitoes, so avoiding bites matters even more.

If the trip cannot wait, see a travel doctor in person well before you go, along with your pregnancy care team. Doxycycline is not used in pregnancy, and the combination tablet is generally avoided because there is too little safety information, so mefloquine is the medicine usually considered; it is only available on prescription in Australia. Breastfeeding or trying to conceive changes the choice too.

When to See a Doctor About Malaria Medicines

See a doctor well before you leave, ideally six to eight weeks ahead, so there is time to start and settle into the right medicine. A travel doctor or clinic in person also gives the vaccines you may need, which a phone consult cannot replace, but even a last minute trip is worth a consult, as some tablets start only a day or two before.

During and after your trips, see a doctor the same day for any fever, and say where you have been. Stopping early is a common reason prevention fails, so finish the course even when you feel well, and if a side effect makes a tablet hard to take, ask about switching rather than stopping.

Summary

This guide has explained what antimalarial drugs do, the main kinds, who needs them, and why avoiding bites and a fast blood test for any fever matter just as much. A Medio GP can talk antimalarial drugs through with you by phone consult, look at your trip and your health, and arrange an eScript where the doctor thinks it right, while vaccines need a travel clinic in person.

Frequently asked questions

What are the most common antimalarial drugs?

The most common antimalarial drugs for travellers are doxycycline, a combination of atovaquone with proguanil, and mefloquine, all only available on prescription in Australia. How long you take antimalarial medicine for depends on which one: seven days after you leave for the combination, and four weeks for the other two. However long the course, continue taking the tablets for that whole time after leaving a malaria area.

What antimalarial drugs are used in Australia?

The same three are used here, chosen by a doctor for each traveller. The side effects of antimalarial medications are usually mild: an upset stomach with any of them, sunburn and heartburn with doxycycline, which is best taken with food and a full glass of water while sitting up, and vivid dreams, anxiety or low mood with mefloquine, which can occasionally last.

Which anti-malaria tablets are the best?

No single tablet is best for everyone. The antimalarial drug you take is chosen with your doctor to fit where you are going, how long you will stay and your health. Countries where you need to take tablets against malaria include most of sub-Saharan Africa, Papua New Guinea and the Solomon Islands, and rural parts of Asia and South America. In Africa, you usually do not need tablets against malaria in Egypt, Morocco or Tunisia, or in Cape Town and Johannesburg, though north eastern South Africa does carry a risk. To avoid malaria, pair any tablet with bite avoidance.

What is the 4 tablet malaria drug?

No medicine goes by that name. People usually mean a treatment course taken as four tablets at a time over three days, which is how some combination treatments for a confirmed infection are given. It is a treatment dose, chosen by a doctor after a blood test shows malaria, or carried as standby treatment for remote travel on a travel doctor's advice, and only available on prescription.

What is the strongest anti-malaria drug?

No preventive medicine is the strongest; each works well where it is matched to the area and to you. The most powerful treatments are kept for a confirmed infection, given in hospital for severe illness. There are five different types of malaria parasite that infect people, and falciparum, common in Africa and Papua New Guinea, is the one that can turn severe, which is why a fever after travel needs a blood test that day.

Who is at risk of malaria?

Anyone bitten by an infected mosquito in a malaria area is at risk, because malaria is spread by mosquito bites, not from person to person. The chance is higher on long stays, in rural areas and when visiting family overseas, and illness is more severe for pregnant women, older adults, and people with no spleen or a weakened immune system. Some people who grew up with malaria are partly immune, but that protection fades within a year or so of living elsewhere and is never complete, so they need protection too. A child going on such a trip should see their own GP or a travel doctor in person.