What is Mefloquine hydrochloride used for?

It is used to treat mild to moderate malaria or to prevent malaria infections before and during travel.

Can Mefloquine hydrochloride cause mental health problems?

Yes, Mefloquine can cause serious psychiatric and neurological reactions that may last after you stop taking it.

When should I start taking Mefloquine hydrochloride for malaria prevention?

You should start taking it one week before you arrive in an area where malaria is common.

How long should I continue Mefloquine hydrochloride after traveling?

You should continue taking it for four weeks after leaving the malaria-prone area.

Can I take Mefloquine hydrochloride on an empty stomach?

No, you should not take it on an empty stomach and should take it with at least 8 oz of water.

Is Mefloquine hydrochloride safe for people with depression?

No, it should not be used for malaria prevention in people with active depression or a recent history of depression.

What should I do if I experience psychiatric symptoms while taking Mefloquine hydrochloride?

You should stop taking the drug immediately and switch to an alternative medication.

Can Mefloquine hydrochloride be used for babies?

It has not been established as safe or effective for babies under 6 months of age.

Mefloquine Hydrochloride | CAS 51773-92-3 | WESWYMRNZNDGBX

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Antimalarial

Mefloquine hydrochloride is an antimalarial medicine used to treat or prevent malaria caused by certain types of parasites. It is taken as an oral tablet. Because it can cause serious mental health and neurological side effects that may last even after you stop taking it, it is not recommended for people with a history of psychiatric disorders.

How it worksMefloquine hydrochloride works by inhibiting a substance called Ferriprotopoerporyn IX, which helps stop the malaria parasite.

Brand names:MEFLOQUINE HYDROCHLORIDE

Used for

Treatment of mild to moderate malaria caused by P. falciparum or P. vivaxPrevention (prophylaxis) of P. falciparum and P. vivax malaria

Conditions

Malaria

Class

Antimalarial4-quinolinemethanol derivativeNervous systemCardiovascular systemImmune system

How to take

FormsOral tablet (250 mg)

RoutesOral

For treating mild to moderate malaria in adults, a single dose of 1250 mg is used. For preventing malaria, one 250 mg tablet is taken once a week.

When treating malaria, do not take the medicine on an empty stomach; take it with at least 8 oz of water. For prevention, take the weekly dose on the same day each week, preferably after a main meal. If you are traveling, start taking it one week before you arrive in the area and continue for four weeks after you leave.

Key warnings

Mefloquine can cause serious mental health and nerve-related problems that may continue even after you stop taking the drug. It should not be used for prevention in people with major psychiatric disorders.

·Mefloquine can cause serious mental health and nerve-related problems that may continue even after you stop taking the drug. It should not be used for prevention in people with major psychiatric disorders.
·If you experience psychiatric or neurological symptoms while taking mefloquine for prevention, stop taking it and find an alternative medication.
·In cases of very severe or life-threatening malaria, intravenous medication should be used first.
·Taking mefloquine with certain other drugs (like halofantrine or ketoconazole) can cause dangerous heart rhythm changes.
·Taking mefloquine with other antimalarials like quinine or chloroquine may increase the risk of seizures or heart issues.

Do not use if

·Known allergy to mefloquine, quinine, or quinidine
·Active depression
·Recent history of depression
·Generalized anxiety disorder
·Psychosis or schizophrenia
·Other major psychiatric disorders
·History of convulsions (seizures)

Side effects

Common

VomitingDizzinessHeadacheNauseaDiarrheaFatigueMuscle pain (myalgia)FeverChillsAbdominal painTinnitus (ringing in the ears)

Serious

·Severe mental health issues (neuropsychiatric reactions)
·Seizures
·Heart rhythm problems (QTc prolongation)
·Cardiopulmonary arrest
·Encephalopathy

Seek help if

·Psychiatric or neurological symptoms
·Heart palpitations or irregular heartbeat
·Seizures

Interactions

·Halofantrine (do not use together or within 15 weeks of each other)
·Ketoconazole (do not use together or within 15 weeks of each other)
·Other antimalarials like quinine, quinidine, or chloroquine (may increase seizure or heart risks)
·Beta-blockers like propranolol (one report of heart arrest when used together)

FoodFood can increase how much of the drug your body absorbs by about 40%. It is recommended to take the medicine with food to avoid an empty stomach.

Special populations

PregnancyInformation regarding use during pregnancy is not fully detailed in the provided text, though it is listed as a section. Caution is advised.

BreastfeedingMefloquine passes into breast milk in small amounts. Use caution when taking this medicine if you are nursing.

PediatricMefloquine can be used in children under 16 for certain malaria types based on adult studies, but it has not been proven safe or effective for babies under 6 months old.

GeriatricThere is not enough data to know if elderly patients respond differently, but since heart issues are more common in older adults, the benefits and risks of mefloquine should be carefully weighed.

Talk to your doctor

Monitor

·Mental health status
·Neurological symptoms
·Heart rhythm (ECG)
·Signs of malaria relapse

Questions to ask

·Should I avoid Mefloquine due to my history of anxiety or depression?
·Are there other antimalarial options if I have heart concerns?
·How should I manage the medication if I experience dizziness?

Pharmacokinetics

OnsetPlasma concentrations peak 6 to 24 hours after a single dose.

BioavailabilityThe bioavailability of the tablet is over 85%; food increases absorption by about 40%.

ExcretionMefloquine is excreted in human milk in small amounts.

Practical

OverdoseIf an overdose occurs, symptoms may be more intense. There is no specific antidote; treatment focuses on managing symptoms and monitoring heart and mental status.

Ingredients

Allergens

lactose

Inactive

colloidal silicon dioxidecorn starchcrosspovidonelactose monohydratemagnesium stearatemicrocrystalline cellulosepregelatinized starchpoloxamertalc

Educational summary derived from FDA labeling, AI-assisted. Not medical advice — consult a healthcare professional. Updated 2026-04-25.