Mefloquine: What You Need to Know Before Travel
Mefloquine is an antimalarial many travelers still use because it’s taken once a week. That once-a-week schedule is handy, but mefloquine comes with side effects you should know about before you pack your bag. This page breaks down how it’s used, what to watch for, and safer options if mefloquine isn’t a fit for you.
How mefloquine is used
For malaria prevention, adults usually take 250 mg once a week. Start at least 1 week before entering a malaria area, keep taking it every week while there, and continue for 4 weeks after you leave. That schedule helps the drug build up and protect you. For treatment, doctors use different dosing—don’t self-treat. Always follow a prescriber's instructions.
Common side effects and red flags
The most common complaints are dizziness, nausea, and vivid dreams. Some people get headaches or stomach upset. More serious problems involve the brain: anxiety, depression, panic attacks, hallucinations, or even psychosis. If you have any history of mental health issues, tell your doctor—mefloquine can make those worse. Stop the drug and get medical help if you notice sudden mood changes, hallucinations, or seizures.
There’s also a heart angle: mefloquine can affect heart rhythm in rare cases. If you’re on medicines that change the QT interval or you have a heart condition, talk to your clinician before starting it.
A practical tip: avoid heavy drinking while on mefloquine. Alcohol can make dizziness, mood swings, and sleep problems worse.
If you miss a weekly dose, take it as soon as you remember. Don’t double up the same day—ask your prescriber or pharmacist for specific advice.
Keep an eye on any new symptoms during travel. Mental or neurological symptoms can start days or weeks after you begin mefloquine. Don’t ignore changes in mood or thinking just because you’re on holiday.
Pregnancy and breastfeeding require a talk with a clinician. In some areas and situations, doctors may still recommend mefloquine, but they’ll weigh risks and benefits carefully.
Interactions matter. Tell your provider about all meds and supplements you use. Mefloquine can interact with other antimalarials and drugs that affect the heart or the nervous system.
If mefloquine sounds risky for you, there are good alternatives: doxycycline (daily pill) and atovaquone-proguanil (daily pill) are commonly used and have different side effect profiles. Your travel destination, medical history, and how long you’ll stay all affect the best choice.
Finally, always get mefloquine from a licensed pharmacy with a valid prescription. Check the package for the expiry date and store it away from heat and moisture. If you have doubts, ask a pharmacist—better safe than sorry.
Want help deciding? Tell your travel clinic about any mental health history, heart issues, or current meds. That info makes picking the safest, most effective malaria prevention plan much easier.
