Lariam Side Effects Center

Last updated on RxList: 6/10/2021
Lariam Side Effects Center

What Is Lariam?

Lariam (mefloquine hydrochloride) is an antimalarial agent used to treat or prevent malaria. Lariam is available in generic form.

What Are Side Effects of Lariam?

Common side effects of Lariam include:

Tell your doctor if you have serious side effects of Lariam including:

  • loss of coordination,
  • numbness and tingling of hands or feet,
  • vision changes,
  • unusual tiredness,
  • persistent nausea or vomiting,
  • dark urine, or
  • yellowing skin or eyes.

Dosage for Lariam

For treatment of mild to moderate malaria in adults, five tablets (1250 mg) of Lariam are given as a single oral dose. To prevent malaria, prophylaxis should begin 1 week before arrival in an endemic area, and then one 250 mg Lariam tablet once weekly. Pediatric dose is determined by the child's weight.

What Drugs, Substances, or Supplements Interact with Lariam?

Lariam may interact with blood thinners, ketoconazole, rifabutin, rifampin, tetracycline, or metoclopramide. Tell your doctor all medications you are taking.

Lariam During Pregnancy or Breastfeeding

Lariam should be used only when prescribed during pregnancy. This drug passes into breast milk. Consult your doctor before breastfeeding.

Additional Information

Our Lariam (mefloquine hydrochloride) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Lariam Consumer Information

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Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop taking mefloquine and call your doctor right away if you any of these side effects:

  • sudden headache, ringing in your ears, dizziness, loss of balance, or problems with coordination;
  • severe anxiety, depression;
  • paranoia, hallucinations (seeing or hearing things that are not real);
  • confusion, unusual behavior; or
  • thoughts about suicide or hurting yourself.

Stop using mefloquine and call your doctor at once if you have:

  • a light-headed feeling, like you might pass out;
  • seizure (convulsions);
  • increased blood pressure--severe headache, blurred vision, chest pain, shortness of breath, uneven heartbeats; or
  • liver problems--nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Common side effects may include:

  • stomach pain, vomiting, diarrhea;
  • dizziness;
  • muscle pain;
  • fever, chills; or
  • mild skin rash.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Lariam Professional Information



At the doses used for treatment of acute malaria infections, the symptoms possibly attributable to drug administration cannot be distinguished from those symptoms usually attributable to the disease itself.

Among subjects who received mefloquine for prophylaxis of malaria, the most frequently observed adverse experience was vomiting (3%). Dizziness, syncope, extrasystoles and other complaints affecting less than 1% were also reported.

Among subjects who received mefloquine for treatment, the most frequently observed adverse experiences included: dizziness, myalgia, nausea, fever, headache, vomiting, chills, diarrhea, skin rash, abdominal pain, fatigue, loss of appetite, and tinnitus. Those side effects occurring in less than 1% included bradycardia, hair loss, emotional problems, pruritus, asthenia, transient emotional disturbances and telogen effluvium (loss of resting hair). Seizures have also been reported.

Two serious adverse reactions were cardiopulmonary arrest in one patient shortly after ingesting a single prophylactic dose of mefloquine while concomitantly using propranolol (see PRECAUTIONS: DRUG INTERACTIONS), and encephalopathy of unknown etiology during prophylactic mefloquine administration. The relationship of encephalopathy to drug administration could not be clearly established.


Postmarketing surveillance indicates that the same kind of adverse experiences are reported during prophylaxis, as well as acute treatment. Because these experiences are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to Lariam (mefloquine) exposure.

The most frequently reported adverse events are nausea, vomiting, loose stools or diarrhea, abdominal pain, dizziness or vertigo, loss of balance, and neuropsychiatric events such as headache, somnolence, and sleep disorders (insomnia, abnormal dreams). These are usually mild and may decrease despite continued use. In a small number of patients it has been reported that dizziness or vertigo and loss of balance may continue for months after discontinuation of the drug.

Occasionally, more severe neuropsychiatric disorders have been reported such as: sensory and motor neuropathies (including paresthesia, tremor and ataxia), convulsions, agitation or restlessness, anxiety, depression, mood changes, panic attacks, forgetfulness, confusion, hallucinations, aggression, psychotic or paranoid reactions and encephalopathy. Rare cases of suicidal ideation and suicide have been reported though no relationship to drug administration has been confirmed.

Other infrequent adverse events include:

Cardiovascular Disorders: circulatory disturbances (hypotension, hypertension, flushing, syncope), chest pain, tachycardia  or palpitation, bradycardia, irregular pulse, extrasystoles, A-V block, and  other transient cardiac conduction alterations

Skin Disorders: rash, exanthema, erythema, urticaria, pruritus, edema, hair loss, erythema multiforme, and Stevens-Johnson syndrome

Musculoskeletal Disorders: muscle weakness, muscle cramps, myalgia, and arthralgia

Respiratory Disorders: dyspnea, pneumonitis of possible allergic etiology

Other Symptoms: visual disturbances, vestibular disorders including tinnitus and hearing impairment, asthenia, malaise, fatigue, fever, sweating, chills, dyspepsia and loss of appetite


The most frequently observed laboratory alterations which could be possibly attributable to drug administration were decreased hematocrit, transient elevation of transaminases, leukopenia and thrombocytopenia. These alterations were observed in patients with acute malaria who received treatment doses of the drug and were attributed to the disease itself.

During prophylactic administration of mefloquine to indigenous populations in malaria-endemic areas, the following occasional alterations in laboratory values were observed: transient elevation of transaminases, leukocytosis or thrombocytopenia.

Because of the long half-life of mefloquine, adverse reactions to Lariam (mefloquine) may occur or persist up to several weeks after the last dose.

Read the entire FDA prescribing information for Lariam (Mefloquine)

© Lariam Patient Information is supplied by Cerner Multum, Inc. and Lariam Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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