Antimalarial Prophylaxis Selector
Lariam is a brand name for mefloquine, an antimalarial medication used for preventive chemotherapy against Plasmodium falciparum. It was approved by the US Food and Drug Administration (FDA) in 1989 and later incorporated into the World Health Organization (WHO) malaria‑prevention guidelines.
Quick Takeaways
- Lariam offers once‑weekly dosing but carries a higher risk of neuro‑psychiatric side effects.
- Doxycycline is taken daily, works well for short‑term trips, but can cause photosensitivity.
- Atovaquone‑proguanil (Malarone) is daily, well‑tolerated, but pricier than generic options.
- Primaquine and tafenoquine target liver‑stage parasites; they’re essential for relapsing malaria.
- Choosing the right drug depends on travel duration, destination resistance patterns, personal health, and tolerance for side effects.
How Lariam Works
Lariam’s active ingredient, mefloquine, interferes with the parasite’s ability to detoxify haem, a by‑product of haemoglobin digestion. By disrupting this pathway, the drug kills mature blood‑stage parasites. Its long half‑life (≈20days) allows a once‑weekly schedule, which many travellers find convenient.
However, that same persistence means the drug accumulates in brain tissue, a factor linked to the infamous neuro‑psychiatric profile. The FDA’s 2013 safety communication warned about vivid dreams, anxiety, depression, and, in rare cases, psychosis. For this reason, the WHO recommends Lariam only when other options are unsuitable or when resistance to alternatives is high.
Key Alternatives to Lariam
Doxycycline is a broad‑spectrum tetracycline antibiotic that also blocks malaria parasite protein synthesis. It must be taken daily, starting 1‑2days before travel and continuing for 4weeks after return.
Atovaquone‑proguanil, marketed as Malarone, combines a mitochondrial electron‑transport inhibitor with a dihydrofolate‑reductase blocker. It’s taken daily, starting 2days before departure and lasting 7days after return. Its short half‑life (≈2‑3days) means rapid clearance, reducing post‑travel dosing.
Primaquine is an 8‑aminoquinoline that targets dormant liver forms (hypnozoites) of P. vivax and P. ovale. It’s administered daily for 14days, but requires a G6PD deficiency test because of hemolysis risk.
Tafenoquine is a newer 8‑aminoquinoline approved in 2018 for both prophylaxis and radical cure. A single weekly dose (once a week) replaces the 14‑day primaquine course, yet it also mandates G6PD screening.
Both the FDA and WHO maintain up‑to‑date resistance maps, showing that chloroquine resistance is near‑universal in sub‑Saharan Africa, while atovaquone‑proguanil resistance remains rare. Doxycycline and mefloquine retain activity across most endemic zones, but regional data should guide final choice.
Side‑Effect Profiles at a Glance
| Drug | Mechanism | Dosing Schedule | Efficacy (P. falciparum) | Key Side Effects | Typical Contra‑indications |
|---|---|---|---|---|---|
| Lariam (mefloquine) | Haem‑polymerisation disruption | Weekly, start 2weeks before, continue 4weeks after | ≈90‑95% | Vivid dreams, anxiety, depression, vertigo | History of psychosis, epilepsy, severe liver disease |
| Doxycycline | Protein synthesis inhibition | Daily, start 1‑2days before, continue 4weeks after | ≈85‑90% | Photosensitivity, gastrointestinal upset, esophagitis | Pregnancy (2nd/3rd trimester), children <8yr |
| Atovaquone‑proguanil | Electron‑transport inhibition + DHFR blockade | Daily, start 2days before, continue 7days after | ≈92‑97% | Transient GI discomfort, mild headache | Severe renal impairment, hypersensitivity |
| Primaquine | 8‑aminoquinoline, targets hypnozoites | Daily, 14days (no loading) | Effective for P. vivax/ovale relapse | Hemolysis in G6PD‑deficient, GI upset | G6PD deficiency, pregnancy (first trimester) |
| Tafenoquine | Long‑acting 8‑aminoquinoline | Weekly dose, start 6days before, continue 4weeks after | Similar to primaquine for relapse | Same hemolysis risk, occasional dizziness | G6PD deficiency, severe renal disease |
Choosing the Right Prophylaxis for Your Trip
Think of drug selection as a match‑making exercise between three variables: destination resistance, travel logistics, and personal health.
- Resistance patterns: Check the latest WHO malaria map. If you’re heading to Southeast Asia where mefloquine resistance is climbing, favour atovaquone‑proguanil or doxycycline.
- Trip length: For trips under 4weeks, doxycycline’s daily regimen is manageable. For longer stays (months), the weekly convenience of Lariam or tafenoquine can improve adherence.
- Medical history: Anyone with a documented psychiatric disorder should avoid mefloquine. Pregnant travellers should steer clear of doxycycline and the 8‑aminoquinolines.
- Cost considerations: Generic mefloquine and doxycycline are inexpensive (underAU$30 for a month’s supply). Atovaquone‑proguanil and tafenoquine are pricier, often exceeding AU$150 for a 4‑week course.
Consulting your travel clinic remains essential. They can perform G6PD testing, review drug‑interaction charts (e.g., mefloquine with antiepileptics, doxycycline with calcium supplements), and tailor a regimen.
Managing Common Side Effects
Even the most tolerable drug can cause trouble if taken wrong. Here are practical tips:
- Lariam: Take the dose with a full glass of water, preferably at night. Split the tablet if nausea occurs. If vivid dreams or anxiety appear, consult a clinician-dose adjustment or switch may be needed.
- Doxycycline: Consume with food or a full glass of milk to reduce stomach irritation. Use sunscreen and wear protective clothing to guard against photosensitivity.
- Atovaquone‑proguanil: Take with a fatty meal; absorption improves dramatically. If you experience mild headache, hydration helps.
- Primaquine / Tafenoquine: Verify G6PD status first. Stay hydrated and avoid high‑intensity exercise during the 14‑day primaquine course to limit hemolysis risk.
Keep a symptom diary-record timing, severity, and any triggers. This information speeds up clinical decisions if you need to switch drugs mid‑trip.
Related Concepts and Next Steps
Understanding malaria prophylaxis touches several adjacent topics:
- G6PD deficiency is an inherited enzyme disorder that predisposes patients to hemolysis when exposed to certain oxidant drugs, including primaquine and tafenoquine.
- Insecticide‑treated nets (ITNs) provide physical protection and reduce mosquito bite rates, complementing chemoprophylaxis.
- Rapid diagnostic tests (RDTs) enable early detection of breakthrough infections, essential when travelling on a marginally effective regimen.
- Vaccination advances such as the RTS,S/Mosquirix vaccine, approved for children in high‑transmission zones, may alter future prophylaxis strategies.
Future articles could explore "How to interpret malaria resistance maps" or "Managing G6PD testing in remote travel clinics"-both natural extensions of this comparison.
Frequently Asked Questions
Can I take Lariam and doxycycline together?
Combining the two isn’t recommended because both increase the risk of neuro‑psychiatric side effects and they offer overlapping protection. If one drug fails, switch to the other after a washout period, not stack them.
What should I do if I develop vivid dreams on Lariam?
Stop the drug immediately and contact a healthcare provider. In many cases, switching to doxycycline or atovaquone‑proguanil resolves the issue. Do not resume Lariam without medical clearance.
Is tafenoquine effective for short trips?
Tafenoquine’s weekly dosing is ideal for trips longer than a week. For very short trips (<7days), atovaquone‑proguanil or doxycycline are simpler because they achieve protective blood levels faster.
Do I need a G6PD test for every antimalarial?
Only the 8‑aminoquinolines (primaquine and tafenoquine) require G6PD screening. All other options, including Lariam, doxycycline, and atovaquone‑proguanil, are safe for G6PD‑deficient individuals.
Which drug is cheapest for a three‑month stay in Africa?
Generic mefloquine (Lariam) and doxycycline are the most affordable, typically under AU$30 per month. Atovaquone‑proguanil can exceed AU$150 for the same period, making it less economical unless tolerability is a priority.
Can I take Lariam if I have a history of depression?
No. The FDA and WHO list a prior depressive disorder as a contraindication for mefloquine. Opt for doxycycline or atovaquone‑proguanil, and discuss your mental‑health history with your clinician.