Malaria prevention drugs for travellers: timing, side effects and teaching

Why timing differs between drugs

Prophylaxis aims to have protective drug levels in place before the first mosquito bite and to keep them long enough afterwards to deal with parasites acquired near the end of the trip. Drugs that act on the liver stage need a short tail after leaving, while those acting on blood stages need several weeks.

Per CDC guidance, atovaquone-proguanil and doxycycline start one to two days before travel; atovaquone-proguanil continues for seven days after leaving, doxycycline for four weeks. Chloroquine and mefloquine are weekly drugs started weeks before travel and continued four weeks after. Tafenoquine starts three days before. The prescriber picks the drug based on destination, history and pregnancy status.

Practical planning starts at the travel consultation, ideally several weeks before departure. Ask the destination, length of stay, activities, current medicines, pregnancy status, and history of depression, seizures or heart rhythm problems. Mefloquine, for example, is avoided with certain drugs that prolong the QT interval, so a full medication list matters even for a healthy traveller going on holiday.

Mefloquine: neuropsychiatric warnings

Mefloquine carries a boxed warning for neuropsychiatric reactions, including anxiety, paranoia, depression, hallucinations and psychotic behaviour, and for neurological effects such as dizziness, vertigo, tinnitus and loss of balance. These can persist after the drug is stopped and have occasionally been permanent. Suicidal thoughts have been reported.

It is contraindicated for prevention in people with active or recent depression, generalised anxiety disorder, psychosis or a history of seizures, so a mental health and seizure history is part of the assessment. Teach travellers to stop and seek an alternative if psychiatric or neurological symptoms appear. It is taken with food and a full glass of water.

Doxycycline, primaquine and tafenoquine cautions

Doxycycline causes photosensitivity, so teach sun protection with clothing and sunscreen, which matters on a tropical trip. It can also cause oesophageal irritation, so it is taken with plenty of water while upright and not just before lying down. Daily dosing for four weeks after return is where adherence often lapses.

Primaquine and tafenoquine can cause haemolysis in people with G6PD deficiency, so a quantitative G6PD test must be done before they are prescribed. Pregnancy narrows the options considerably, so ask about pregnancy and plans before the drug is chosen. Atovaquone-proguanil is generally well tolerated but is still a daily commitment.

Teaching beyond the tablets

No prophylactic drug is completely protective, so insect repellent, covered skin and bed nets remain part of the plan. Teach a missed-dose plan for the chosen drug and stress that stopping when the trip ends is the most common mistake, especially with drugs that continue for four weeks after leaving.

Most importantly, fever during or after travel to a malaria area needs urgent medical assessment, even if the traveller took prophylaxis perfectly, and they should mention the trip. Malaria can appear weeks to months after return. Ask for teach-back of the start date, stop date and the fever rule before the traveller leaves.

Worked scenario: choosing who needs a second look

In a hypothetical travel clinic, a traveller prescribed weekly mefloquine mentions they stopped an antidepressant two months ago after a depressive episode. They leave in three weeks. Options are to give the first dose and teaching as planned, tell them to restart the antidepressant, or report the history before the drug is dispensed.

Reporting before dispensing is best. Recent depression is a contraindication to mefloquine for prevention, and the prescriber can choose an alternative with a different timetable. Restarting an antidepressant is not a nursing decision and would not remove the risk. The nurse documents the history and updates the teaching once a new drug is chosen.

Sources and further reading

CDC Yellow Book: Malaria. Start and stop timing for each drug, doxycycline photosensitivity and oesophagitis, G6PD testing, pregnancy options, bite prevention and fever after travel.

DailyMed: Mefloquine hydrochloride tablets prescribing information. Boxed neuropsychiatric warning, persistence after stopping, contraindications, continuation after travel and taking with food and water.