TL;DR
- Lariam (mefloquine) is a prescription antimalarial used for prevention and treatment of certain malaria strains.
- Standard adult prophylaxis dose: 250mg taken weekly, starting 1‑2 weeks before travel and continuing 4 weeks after returning.
- Common side effects: dizziness, insomnia, vivid dreams, and mild GI upset; serious neuro‑psychiatric reactions are rare but require immediate medical attention.
- Do NOT combine Lariam with certain antidepressants, anti‑seizure meds, or other QT‑prolonging drugs without doctor oversight.
- Always discuss pre‑existing mental health conditions with your provider before starting Lariam.
What Is Lariam and How It Works?
Lariam is the brand name for mefloquine, a synthetic quinoline‑related compound discovered in the 1970s. It targets the Plasmodium parasite that causes malaria, especially the P. falciparum strains resistant to older drugs like chloroquine.
The drug interferes with the parasite’s ability to detoxify heme, a toxic by‑product of its digestion of red blood cells. When heme accumulates, the parasite dies. Because mefloquine has a long half‑life (about 20‑30 days), a single weekly dose can maintain protective blood levels.
Doctors usually prescribe Lariam for travelers heading to regions where chloroquine‑resistant malaria is prevalent, such as most of sub‑Saharan Africa, parts of Southeast Asia, and certain areas of South America. It’s also used, less commonly, to treat acute malaria infections when other agents are unsuitable.
Dosage, Administration, and Safety Tips
Getting the dosing right is the cornerstone of effective malaria prevention. Below is the most widely accepted schedule for healthy adults:
- Loading phase: Take one 250mg tablet (½tablet) 1-2 weeks before entering the malaria‑risk zone.
- Weekly maintenance: Continue with one 250mg tablet every 7±2 days while in the endemic area.
- Post‑travel phase: Keep the weekly dose for four weeks after leaving the region. This covers the parasite’s incubation period.
If you’re a child, pregnant, or have liver/kidney impairment, the dosage may differ. Pediatric dosing is weight‑based (5mg/kg weekly), and pregnant women in the first trimester are usually advised to avoid Lariam altogether.
Key safety pointers:
- Take the tablet with food and a full glass of water to lessen stomach upset.
- Set a recurring alarm on your phone; missing a weekly dose reduces protection dramatically.
- If you miss a dose and are within 48hours of the scheduled day, take it as soon as you remember and keep the subsequent schedule unchanged.
- Do not double‑dose to “catch up” - the drug’s long half‑life means excess amounts can increase side‑effect risk.
- Store Lariam at room temperature, away from moisture and direct sunlight.
Before starting Lariam, your clinician should screen for:
- History of depression, anxiety, or psychosis.
- History of seizures or other neurological disorders.
- Cardiac conditions, especially prolonged QT interval.
- Current use of antidepressants (SSRIs, SNRIs), antipsychotics, or anti‑arrhythmic drugs.
These factors can raise the odds of neuro‑psychiatric side effects, which, while uncommon, can be serious.
Side Effects, Drug Interactions, and Frequently Asked Questions
Understanding what to expect helps you react quickly if something goes wrong.
| Side Effect | Frequency | Typical Management |
|---|---|---|
| Dizziness, light‑headedness | Common (1‑10%) | Take with food; avoid rapid position changes. |
| Insomnia or vivid dreams | Common (1‑10%) | Take dose in the morning; consider melatonin. |
| GI upset (nausea, abdominal pain) | Common (1‑10%) | Take with a meal; stay hydrated. |
| Headache | Uncommon (0.1‑1%) | Hydration, OTC acetaminophen if needed. |
| Neuro‑psychiatric reactions (anxiety, depression, psychosis) | Rare (<0.1%) | Stop drug immediately; seek medical attention. |
| Cardiac arrhythmia (QT prolongation) | Rare (<0.1%) | Baseline ECG for high‑risk patients; discontinue if abnormal. |
Most side effects are mild and subside within a few weeks as your body adjusts. However, any sudden mood swings, hallucinations, or severe anxiety should trigger an immediate stop of the medication and a call to a health professional.
Important drug interactions:
- Antidepressants - SSRIs, SNRIs, tricyclics can amplify neuro‑psychiatric risk.
- Anti‑seizure meds - carbamazepine, phenytoin can lower mefloquine levels, reducing efficacy.
- QT‑prolonging agents - certain anti‑arrhythmics, some macrolide antibiotics, and fluoroquinolones may increase cardiac risk.
- Alcohol - worsens dizziness and CNS side effects; limit intake.
If you’re on any of the above, discuss alternatives like atovaquone‑proguanil (Malarone) or doxycycline with your provider.
Quick FAQ
- Can I take Lariam if I’m pregnant? Only in the second and third trimesters if no safer alternative is available. First‑trimester exposure is generally avoided.
- How long does it stay in my system? The drug’s half‑life means detectable levels can linger for weeks after the last dose, which is why the four‑week post‑travel regimen is crucial.
- Do I need a prescription? Yes. Lariam is prescription‑only in most countries due to its side‑effect profile.
- What should I do if I miss a dose? If within 48hours, take it as soon as you remember. If more than 48hours have passed, contact your doctor; you may need a backup prophylactic (e.g., atovaquone‑proguanil) for the remaining travel period.
- Is Lariam effective against all malaria species? It’s highly effective against P. falciparum and P. vivax in regions where resistance hasn’t emerged. Check CDC or WHO maps for current resistance patterns.
Next Steps & Troubleshooting
If you’re preparing for a trip:
- Schedule an appointment with a travel clinic at least 4-6 weeks before departure.
- Bring a complete medication list so the clinician can spot interactions.
- Ask for a written schedule (start date, weekly dosing day, end date) and a pocket‑size reminder card.
- Consider packing an extra tablet in case you lose your supply, but never double‑dose.
If you’ve already started Lariam and notice side effects:
- Track symptoms in a notebook - note timing, severity, and any triggers.
- Contact your healthcare provider if neuro‑psychiatric symptoms appear; they may switch you to an alternative regimen.
- For mild GI upset, try taking the tablet with a larger meal or an antacid (if approved by your doctor).
- Stay hydrated and maintain a regular sleep schedule to mitigate insomnia.
By following these guidelines, you can protect yourself from malaria while minimizing the hassle of side effects. Remember, the best defense is a well‑planned travel health strategy, not just a single medication.
