Symptoms of malaria can develop as quickly as 7 days after you're bitten by an infected mosquito.

Typically, the time between being infected and when symptoms start (incubation period) is 7 to 18 days, depending on the specific parasite you're infected with. However, in some cases it can take up to a year for symptoms to develop.

The initial symptoms of malaria are flu-like and include:

• a high temperature of 38C or above
• feeling hot and shivery
• headaches
• vomiting
• muscle pains
• diarrhoea
• generally feeling unwell

These symptoms are often mild and can sometimes be difficult to identify as malaria.

With some types of malaria, the symptoms occur in 48-hour cycles. During these cycles, you feel cold at first with shivering. You then develop a high temperature, accompanied by severe sweating and fatigue. These symptoms usually last between 6 and 12 hours.

The most serious type of malaria is caused by the Plasmodium falciparum parasite. Without prompt treatment, this type could lead to you quickly developing severe and life-threatening complications, such as breathing problems and organ failure.

Read more about the complications of malaria.

Seeking medical advice

Seek medical advice immediately if you develop symptoms of malaria during or after a visit to an area where the disease is found.

You should still seek medical help even if it's several weeks, months or a year after you return from travelling.

Malaria is caused by the Plasmodium parasite. The parasite can be spread to humans through the bites of infected mosquitoes.

There are many different types of plasmodium parasite, but only 5 types cause malaria in humans.

These are:

• Plasmodium falciparum – mainly found in Africa, it's the most common type of malaria parasite and is responsible for most malaria deaths worldwide
• Plasmodium vivax – mainly found in Asia and South America, this parasite causes milder symptoms than Plasmodium falciparum, but it can stay in the liver for up to 3 years, which can result in relapses
• Plasmodium ovale – fairly uncommon and usually found in West Africa, it can remain in your liver for several years without producing symptoms
• Plasmodium malariae – this is quite rare and usually only found in Africa
• Plasmodium knowlesi – this is very rare and found in parts of southeast Asia

How malaria is spread

The plasmodium parasite is spread by female Anopheles mosquitoes, which are known as "night-biting" mosquitoes because they most commonly bite between dusk and dawn.

If a mosquito bites a person already infected with malaria, it can also become infected and spread the parasite on to other people. However, malaria can't be spread directly from person to person.

Once you're bitten, the parasite enters the bloodstream and travels to the liver. The infection develops in the liver before re-entering the bloodstream and invading the red blood cells.

The parasites grow and multiply in the red blood cells. At regular intervals, the infected blood cells burst, releasing more parasites into the blood. Infected blood cells usually burst every 48-72 hours. Each time they burst, you'll have a bout of fever, chills and sweating.

Malaria can also be spread through blood transfusions and the sharing of needles, but this is very rare.

Antimalarial medication is used to prevent and treat malaria.

You should always consider taking antimalarial medicine when travelling to areas where there's a risk of malaria. Visit your GP or local travel clinic for malaria advice as soon as you know when and where you're going to be travelling.

It's very important to take the correct dose and finish the course of antimalarial treatment. If you're unsure, ask your GP or pharmacist how long you should take your medication for.

Preventing malaria

It's usually recommended you take antimalarial tablets if you're visiting an area where there's a malaria risk as they can reduce your risk of malaria by about 90%.

The type of antimalarial tablets you will be prescribed is based on the following information:

• where you're going
• any relevant family medical history
• your medical history, including any allergies to medication
• any medication you're currently taking
• any problems you've had with antimalarial medicines in the past
• your age
• whether you're pregnant

You may need to take a short trial course of antimalarial tablets before travelling. This is to check that you don't have an adverse reaction or side effects. If you do, alternative antimalarials can be prescribed before you leave.

Types of antimalarial medication

The main types of antimalarials used to prevent malaria are described below.

Atovaquone plus proguanil

• Dosage – the adult dose is 1 adult-strength tablet a day. Child dosage is also once a day, but the amount depends on the child's weight. It should be started 1 or 2 days before your trip and taken every day you're in a risk area, and for 7 days after you return.
• Recommendations – a lack of clear evidence means this antimalarial shouldn't be taken by pregnant or breastfeeding women. It's also not recommended for people with severe kidney problems.
• Possible side effects – stomach upset, headaches, skin rash and mouth ulcers.
• Other factors – it can be more expensive than other antimalarials, so may be more suitable for short trips.

Doxycycline (also known as Vibramycin-D)

• Dosage – the dose is 100mg daily as a tablet or capsule. You should start the tablets 2 days before you travel and take them each day you're in a risk area, and for 4 weeks after you return.
• Recommendations – not normally recommended for pregnant or breastfeeding women, but your GP will advise. Not recommended for children under the age of 12 (because of the risk of permanent tooth discolouration), people who are sensitive to tetracycline antibiotics, or people with liver problems.
• Possible side effects – stomach upset, heartburn, thrush, and sunburn as a result of light sensitivity. It should always be taken with food, preferably when standing or sitting.
• Other factors – it is relatively cheap. If you take doxycycline for acne, it will also provide protection against malaria as long as you're taking an adequate dose. Ask your GP.

Mefloquine (also known as Lariam)

• Dosage – the adult dose is 1 tablet weekly. Child dosage is also once a week, but the amount will depend on their weight. It should be started 3 weeks before you travel and taken all the time you're in a risk area, and for 4 weeks after you get back.
• Recommendations – it's not recommended if you have epilepsy, seizures, depression or other mental health problems, or if a close relative has any of these conditions. It's not usually recommended for people with severe heart or liver problems.
• Possible side effects – dizziness, headache, sleep disturbances (insomnia and vivid dreams) and psychiatric reactions (anxiety, depression, panic attacks and hallucinations). It's very important to tell your doctor about any previous mental health problems, including mild depression. Don't take this medication if you have a seizure disorder.
• Other factors – if you haven't taken mefloquine before, it's recommended you do a 3-week trial before you travel to see whether you develop any side effects.

Chloroquine and proguanil

A combination of antimalarial medications called chloroquine and proguanil is also available, although these are rarely recommended nowadays because they're largely ineffective against the most common and dangerous type of malaria parasite, Plasmodium falciparum.

However, chloroquine and proguanil may occasionally be recommended for certain destinations where the Plasmodium falciparum parasite is less common than other types, such as India and Sri Lanka.

Treating malaria

If malaria is diagnosed and treated promptly, a full recovery can be expected. Treatment should be started as soon as a blood test confirms malaria.

Many of the same antimalarial medicines used to prevent malaria can also be used to treat the disease. However, if you've taken an antimalarial to prevent malaria, you shouldn't take the same one to treat it. This means it's important to tell your doctor the name of the antimalarials you took.

The type of antimalarial medicine and how long you need to take it will depend on:

• the type of malaria you have
• where you caught malaria
• the severity of your symptoms
• whether you took preventative antimalarial tablets
• your age
• whether you're pregnant

Your doctor may recommend using a combination of different antimalarials to overcome strains of malaria that have become resistant to single types of medication.

Antimalarial medication is usually given as tablets or capsules. If someone is very ill, it will be given through a drip into a vein in the arm (intravenously) in hospital.

Treatment for malaria can leave you feeling very tired and weak for several weeks.

Emergency standby treatment

In some cases, you may be prescribed emergency standby treatment for malaria before you travel. This is usually if there's a risk of you becoming infected with malaria while travelling in a remote area with little or no access to medical care.

Examples of emergency standby medications include:

• atovaquone with proguanil
• artemether with lumefantrine
• quinine plus doxycycline
• quinine plus clindamycin

Your GP may decide to seek advice from a travel health specialist before prescribing standby emergency treatment.

Read more about standby emergency treatment for malaria.

Antimalarials in pregnancy

If you're pregnant, it's advisable to avoid travelling to areas where there's a risk of malaria.

Pregnant women have an increased risk of developing severe malaria, and both the baby and mother could experience serious complications.

It's very important to take the right antimalarial medicine if you're pregnant and unable to postpone or cancel your trip to an area where there's a malaria risk.

Some of the antimalarials used to prevent and treat malaria are unsuitable for pregnant women because they can cause side effects for both mother and baby.

The list below outlines which medications are safe or unsafe to use while pregnant:

• Mefloquine – not usually prescribed during the first trimester of pregnancy, or if pregnancy is a possibility during the first 3 months after preventative antimalarial medication is stopped. This is a precaution, even though there's no evidence to suggest mefloquine is harmful to an unborn baby.
• Doxycycline – never recommended for pregnant or breastfeeding women as it could harm the baby.
• Atovaquone plus proguanil – not generally recommended during pregnancy or breastfeeding because research into the effects is limited. However, if the risk of malaria is high, they may be recommended if there's no suitable alternative.

Chloroquine combined with proguanil is suitable during pregnancy, but it is rarely used as it's not very effective against the most common and dangerous type of malaria parasite.

Malaria is a serious illness that can be fatal if not diagnosed and treated quickly. Pregnant women, babies, young children and the elderly are particularly at risk.

The Plasmodium falciparum parasite causes the most severe malaria symptoms and most deaths.

As complications of severe malaria can occur within hours or days of the first symptoms, it's important to seek urgent medical help as soon as possible.

Anaemia

The destruction of red blood cells by the malaria parasite can cause severe anaemia.

Anaemia is a condition where the red blood cells are unable to carry enough oxygen to the body's muscles and organs, leaving you feeling drowsy, weak and faint.

Cerebral malaria

In rare cases, malaria can affect the brain. This is known as cerebral malaria, which can cause your brain to swell, sometimes leading to permanent brain damage. It can also cause fits (seizures) or coma.

Other complications

Other complications that can arise as a result of severe malaria include:

• liver failure and jaundice – yellowing of the skin and whites of the eyes
• shock – a sudden drop in blood pressure
• pulmonary oedema – a build-up of fluid in the lungs
• acute respiratory distress syndrome (ARDS)
• abnormally low blood sugar – hypoglycaemia
• kidney failure
• swelling and rupturing of the spleen
• dehydration

Malaria in pregnancy

The World Health Organization (WHO) recommends that pregnant women should avoid travelling to areas where there's a risk of malaria.

If you get malaria while pregnant, you and your baby have an increased risk of developing serious complications, such as:

• premature birth – birth before 37 weeks of pregnancy
• low birth weight
• restricted growth of the baby in the womb
• stillbirth
• miscarriage
• death of the mother

Visit your GP if you're pregnant and travelling to a high-risk area. They may recommend taking antimalarial medication.

Read more about taking antimalarials while pregnant.

There's a significant risk of getting malaria if you travel to an affected area. It's very important you take precautions to prevent the disease.

Malaria can often be avoided using the ABCD approach to prevention, which stands for:

• Awareness of risk – find out whether you're at risk of getting malaria.
• Bite prevention – avoid mosquito bites by using insect repellent, covering your arms and legs, and using a mosquito net.
• Check whether you need to take malaria prevention tablets – if you do, make sure you take the right antimalarial tablets at the right dose, and finish the course.
• Diagnosis – seek immediate medical advice if you have malaria symptoms, including up to a year after you return from travelling.

These are outlined in more detail below.

Being aware of the risks

To check whether you need to take preventative malaria treatment for the countries you're visiting, see the Fit for Travel website.

It's also important to visit your GP or local travel clinic for malaria advice as soon as you know where you're going to be travelling.

Even if you grew up in a country where malaria is common, you still need to take precautions to protect yourself from infection if you're travelling to a risk area.

Nobody has complete immunity to malaria, and any level of natural protection you may have had is quickly lost when you move out of a risk area.

Preventing bites

It's not possible to avoid mosquito bites completely, but the less you're bitten, the less likely you are to get malaria.

To avoid being bitten:

• Stay somewhere that has effective air conditioning and screening on doors and windows. If this isn't possible, make sure doors and windows close properly.
• If you're not sleeping in an air-conditioned room, sleep under an intact mosquito net that's been treated with insecticide.
• Use insect repellent on your skin and in sleeping environments. Remember to reapply it frequently. The most effective repellents contain diethyltoluamide (DEET) and are available in sprays, roll-ons, sticks and creams.
• Wear light, loose-fitting trousers rather than shorts, and wear shirts with long sleeves. This is particularly important during early evening and at night, when mosquitoes prefer to feed.

There's no evidence to suggest homeopathic remedies, electronic buzzers, vitamins B1 or B12, garlic, yeast extract spread (such as Marmite), tea tree oils or bath oils offer any protection against mosquito bites.

Antimalarial tablets

There's currently no vaccine available that offers protection against malaria, so it's very important to take antimalarial medication to reduce your chances of getting the disease.

However, antimalarials only reduce your risk of infection by about 90%, so taking steps to avoid bites is also important.

When taking antimalarial medication:

• make sure you get the right antimalarial tablets before you go – check with your GP or pharmacist if you're unsure
• follow the instructions included with your tablets carefully
• depending on the type you're taking, continue to take your tablets for up to 4 weeks after returning from your trip to cover the incubation period of the disease

Check with your GP to make sure you're prescribed a medication you can tolerate. You may be more at risk from side effects if you:

• have HIV or AIDS
• have epilepsy or any type of seizure condition
• are depressed or have another mental health condition
• have heart, liver or kidney problems
• take medicine, such as warfarin, to prevent blood clots
• use combined hormonal contraception, such as the contraceptive pill or contraceptive patches

If you've taken antimalarial medication in the past, don't assume it's suitable for future trips. The antimalarial you need to take depends on which strain of malaria is carried by the mosquitoes and whether they're resistant to certain types of antimalarial medication.

In the UK, chloroquine and proguanil can be bought over-the-counter from local pharmacies. However, you should seek medical advice before buying it as it's rarely recommended nowadays. For all other antimalarial tablets, you'll need a prescription from your GP.

Read more about antimalarial medication, including the main types and when to take them.

Get immediate medical advice

You must seek medical help straight away if you become ill while travelling in an area where malaria is found, or after returning from travelling, even if you've been taking antimalarial tablets.

Malaria can get worse very quickly, so it's important that it's diagnosed and treated as soon as possible.

If you develop symptoms of malaria while still taking antimalarial tablets, either while you're travelling or in the days and weeks after you return, remember to tell the doctor which type you have been taking. The same type of antimalarial shouldn't be used to treat you as well.

If you develop symptoms after returning home, visit your GP or a hospital doctor and tell them which countries you've travelled to in the last 12 months, including any brief stopovers.

DEET insect repellents

The chemical DEET is often used in insect repellents. It's not recommended for babies who are less than 2 months old.

DEET is safe for older children, adults and pregnant women if you follow the manufacturer's instructions:

• use on exposed skin
• don't spray directly on to your face – spray into your hands and pat on to your face
• avoid contact with lips and eyes
• wash your hands after applying
• don't apply to broken or irritated skin
• make sure you apply DEET after applying sunscreen, not before