TL;DR
- Lariam (mefloquine) is a prescription antimalarial used for prevention and treatment of Plasmodium vivax and Plasmodium falciparum infections.
- Typical adult prophylaxis: 250mg weekly, starting 1-2weeks before travel and continuing 4weeks after return.
- Common side effects include vivid dreams, dizziness and mild nausea; serious neuro‑psychiatric reactions are rare but require immediate medical attention.
- Contraindicated in people with a history of seizures, severe mental illness, or known hypersensitivity.
- Alternatives such as doxycycline, atovaquone‑proguanil or tafenoquine may be better for those prone to Lariam’s CNS effects.
What is Lariam and when is it used?
Lariam is the brand name for mefloquine, a synthetic quinoline‑based drug first approved in the 1980s. It works by disrupting the malaria parasite’s ability to digest haem, a process essential for its survival inside red blood cells. Because it has a long half‑life (about 20‑days), one weekly tablet can protect a traveller for an entire week.
Health agencies such as the WHO and CDC list mefloquine as a first‑line option for prophylaxis in areas where Plasmodium falciparum shows resistance to older drugs like chloroquine. It’s especially popular for trips to parts of sub‑Saharan Africa, the Amazon basin and some Pacific islands.
How does Lariam work? The science in plain English
When malaria parasites eat up haem (a breakdown product of the blood they consume), they normally detoxify it into a harmless crystal called hemozoin. Mefloquine blocks this detox pathway, causing toxic haem to accumulate and kill the parasite. The drug also interferes with the parasite’s cell membrane, adding a second blow.
The long elimination period means the drug stays in your bloodstream long after the last dose, providing a built‑in safety net if you miss a weekly tablet. However, it also means side effects can linger for weeks, which is why doctors screen patients carefully before prescribing.
Dosage and administration - getting it right
For adults (including most teenagers over 12years), the standard regimen is:
- Start 1-2weeks before entering a malaria‑risk area: 250mg (half a 500mg tablet) each day for three days.
- Continue with a single 250mg dose once a week for the duration of travel.
- Finish the weekly dose 4weeks after leaving the endemic zone.
Children aged 6-12years receive weight‑based dosing (5mg/kgonce weekly) after a similar loading phase. Pregnant women in the first trimester are usually advised against mefloquine because of limited safety data; the drug is considered safer in the second and third trimesters when the benefits outweigh the risks.
Take the tablet with food and a full glass of water to minimise stomach upset. If you vomit within an hour, repeat the dose.
Side effects, safety concerns, and when to stop
Most people tolerate Lariam quite well, but the drug has a reputation for causing central nervous system (CNS) symptoms. Here’s a quick breakdown of what to expect:
| Side effect | Frequency | Typical onset |
|---|---|---|
| Headache, dizziness | Common (1‑10%) | First week |
| Vivid dreams, insomnia | Common (1‑10%) | First 2‑3 weeks |
| Nausea, abdominal pain | Common (1‑10%) | First week |
| Depression, anxiety, panic attacks | Uncommon (0.1‑1%) | 1‑2months into therapy |
| Seizures, psychosis, suicidal thoughts | Rare (<0.1%) | Variable, often early |
If you notice persistent nightmares or anxiety, most clinicians suggest a short break from the drug, followed by a lower maintenance dose (250mg) after the symptoms settle. Serious neuro‑psychiatric signs - such as hearing voices, severe depression, or thoughts of self‑harm - demand an immediate stop and urgent medical review.
Other contraindications include:
- History of seizures or epilepsy.
- Known hypersensitivity to mefloquine or related quinolines.
- Severe liver disease (the drug is metabolised in the liver).
Pregnant women in the first trimester, nursing mothers, and patients with uncontrolled psychiatric illness should avoid Lariam unless there’s no suitable alternative.
Alternatives to Lariam - choosing the right antimalarial for you
Not everyone can tolerate mefloquine. Here’s a quick comparison of the most common substitutes:
- Doxycycline - a daily tablet taken with a full glass of water. Effective everywhere, but photosensitivity and stomach upset are common. Not ideal for pregnant women.
- Atovaquone‑proguanil (Malarone) - taken daily, well‑tolerated, quick onset. Costs more than Lariam and requires a 7‑day lead‑in before travel.
- Tafenoquine - a single‑dose weekly option similar to mefloquine, approved for both prophylaxis and radical cure of P. vivax. Not for G6PD‑deficient patients.
- Chloroquine - still works in a few regions (e.g., parts of Central America). Resistance is widespread, so it’s rarely the first choice.
When deciding, weigh three factors:
- Resistance patterns - check the latest CDC map for your destination.
- Personal health profile - history of seizures, psychiatric conditions, pregnancy status.
- Convenience and cost - weekly vs daily dosing, insurance coverage.
For most travelers with no CNS history, Lariam remains a cost‑effective weekly pill. If you’ve experienced vivid dreams or anxiety on other meds, a switch to doxycycline or atovaquone‑proguanil may provide smoother sailing.
Mini‑FAQ - what else travellers ask about Lariam
- Can I drink alcohol while taking Lariam? Moderate alcohol isn’t prohibited, but both alcohol and mefloquine can worsen dizziness and nausea. It’s safest to limit intake, especially during the loading phase.
- How long does it stay in my system after the last dose? Mefloquine’s half‑life is roughly 20days, so detectable levels can linger for up to 8weeks. That’s why side effects may persist after you stop.
- Is Lariam safe for children? Yes, for kids over 6years and weighing at least 20kg, using weight‑based dosing. Below that, alternatives like doxycycline (if over 8years) or atovaquone‑proguanil are preferred.
- What should I do if I miss a weekly dose? Take it as soon as you remember, then continue the regular schedule. If it’s close to the next dose, skip the missed one and resume the usual day - never double up.
- Can Lariam treat an active malaria infection? Yes, high‑dose mefloquine (usually 1250mg over three days) is used for treatment, but most clinicians prefer combination therapy (e.g., artesunate‑mefloquine) to reduce resistance risk.
Next steps and troubleshooting
If you’re gearing up for a trip to a malaria‑endemic region, follow this quick checklist:
- Consult your GP or a travel clinic at least 2weeks before departure.
- Confirm that Lariam is appropriate for your health history.
- Get a written prescription; many UK pharmacies can dispense it on the same day.
- Set a weekly alarm on your phone to remember the dose.
- Pack a short‑term supply of anti‑emetics (e.g., ondansetron) in case of nausea.
Encountered side effects? Try these simple steps before stopping:
- Take the tablet with a hearty meal and plenty of water.
- Use a sleep mask and earplugs to lessen vivid dreams.
- If dizziness persists, limit caffeine and avoid driving.
Still uncomfortable after a week? Call your clinic. They may lower the dose, switch you to doxycycline, or provide a short‑term steroid burst to calm CNS irritation.
Remember, malaria is a serious disease - prevention, not cure, saves lives. Whether you stick with Lariam or opt for an alternative, the key is to start early, stay consistent, and be aware of how your body reacts.