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Mefloquine Side Effects

Medically reviewed by Last updated on Feb 26, 2024.

Applies to mefloquine: oral tablet.


Oral route (Tablet)

Mefloquine may cause neuropsychiatric adverse reactions that can persist after mefloquine has been discontinued. Mefloquine should not be prescribed for prophylaxis in patients with major psychiatric disorders. During prophylactic use, if psychiatric or neurologic symptoms occur, the drug should be discontinued and an alternative medication should be substituted

Serious side effects of Mefloquine

Along with its needed effects, mefloquine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking mefloquine:


Incidence not known

Other side effects of Mefloquine

Some side effects of mefloquine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common


Incidence not known

For Healthcare Professionals

Applies to mefloquine: oral tablet.


At the doses used for treatment of acute malaria infections, the side effects possibly associated with this drug could not be distinguished from the side effects usually associated with the disease. The most common side effects reported during treatment included dizziness, myalgia, nausea, fever, headache, vomiting, chills, diarrhea, skin rash, abdominal pain, fatigue, loss of appetite, and tinnitus.

The most common side effects reported during malaria prophylaxis included nausea, vomiting, and dizziness.

Due to the long half-life of this drug, side effects have occurred and persisted up to several weeks after drug discontinuation.[Ref]


Very common (10% or more): Abnormal dreams/strange or vivid dreams (13.7%), insomnia (13.5%)

Common (1% to 10%): Depression, anxiety

Frequency not reported: Emotional problems, transient emotional disturbances, behavioral changes, mania, nightmares, delusions, tension, anger, organic psychosis, dysphoria

Postmarketing reports: Anxiety, depression, mood swings, panic attacks, confusion/confusional state, hallucinations, aggression, agitation, restlessness, psychotic/paranoid reactions, suicidal ideation, suicide, attempted suicide, self-endangering behavior, bipolar disorder, psychotic disorder (including delusional disorder, depersonalization, mania, schizophrenia/schizophreniform disorder), paranoia, disturbance in attention[Ref]


Common (1% to 10%): Nausea, diarrhea, abdominal pain, mouth ulcers, vomiting

Postmarketing reports: Nausea, vomiting, abdominal pain, loose stools/diarrhea, dyspepsia, pancreatitis[Ref]

Nervous system

Encephalopathy of unknown etiology was reported during prophylactic use; however, the relationship to drug administration could not be established.[Ref]

Common (1% to 10%): Dizziness, vertigo, headache

Frequency not reported: Syncope, encephalopathy of unknown etiology, tinnitus, seizures, myoclonus

Postmarketing reports: Dizziness, vertigo, loss of balance/balance disorder, neuropsychiatric events (e.g., headache, somnolence), peripheral sensory and motor neuropathies (including paresthesia, tremor, ataxia), convulsions, agitation, restlessness, memory impairment, encephalopathy, vestibular disorders (including tinnitus, hearing impairment), cranial nerve paralysis, amnesia (some lasted more than 3 months), speech disorder, gait disturbance, partial deafness (sometimes prolonged), hyperacusis[Ref]


Common (1% to 10%): Itching/pruritus

Frequency not reported: Skin rash, hair loss, telogen effluvium, cutaneous vasculitis

Postmarketing reports: Rash, exanthema, erythema, urticaria, pruritus, alopecia/hair loss, hyperhidrosis, erythema multiforme, Stevens-Johnson syndrome[Ref]


Common (1% to 10%): Visual difficulties

Postmarketing reports: Visual impairment, blurred vision, cataracts, retinal disorders, optic neuropathy[Ref]


Frequency not reported: Extrasystoles, cardiopulmonary arrest, bradycardia, transitory and clinically silent ECG alterations (including sinus bradycardia, sinus arrhythmia, first degree atrioventricular block, prolongation of the QTc interval, abnormal T waves), atrial flutter

Postmarketing reports: Circulatory disturbances (hypotension, hypertension, flushing, syncope), chest pain, tachycardia, palpitation, bradycardia, irregular heart rate, extrasystoles, atrioventricular block, other transient cardiac conduction alterations[Ref]

Cardiopulmonary arrest was reported in 1 patient after a single prophylactic dose while concomitantly using propranolol.[Ref]


Frequency not reported: Decreased hematocrit, anemia, isolated thrombocytopenia, hemolytic anemia, thrombotic thrombocytopenic purpura

Postmarketing reports: Agranulocytosis, aplastic anemia, leukopenia, leukocytosis, thrombocytopenia[Ref]

A 56-year-old male experienced thrombotic thrombocytopenic purpura (TTP) coincident with use of this drug. A week before admission, the patient developed weakness, followed some days later by anorexia, myalgia, and lethargy, and, finally, by fever, confusion, and blurred vision. A central venous catheter was placed in the right jugular vein and 2 plasmapheresis sessions (12 units of fresh frozen plasma) were conducted in the first 24 hours. Neurological status improved after the first plasmapheresis; hematological abnormalities disappeared in the first few days of therapy. For this patient, the presence of severe neurological symptoms together with fever, thrombocytopenia, and microangiopathic anemia suggested a more complex hematological abnormality, such as TTP. The causal relation between drug and disease is supported by the temporal relation of drug intake with the onset of the clinical symptoms and laboratory abnormalities, as well as by their prompt improvement after the aphaeretic therapy and drug withdrawal.[Ref]


Frequency not reported: Asthenia, fatigue, fever, chills, weakness

Postmarketing reports: Asthenia, edema, chest pain, malaise, fatigue, fever/pyrexia, chills[Ref]


Frequency not reported: Myalgia, moderately severe arthralgias, moderately severe myalgias

Postmarketing reports: Muscle/muscular weakness, muscle spasms/cramps, myalgia, arthralgia[Ref]


Frequency not reported: Hypersensitivity reactions (from mild cutaneous events to anaphylaxis)[Ref]


Frequency not reported: Eosinophilic pneumonia

Postmarketing reports: Dyspnea, pneumonitis of possible allergic etiology, pneumonia[Ref]

A 67-year-old female with a history of pityriasis versicolor experienced eosinophilic pneumonia coincident with infliximab therapy. She was admitted because she had experienced high-grade fever (39C), malaise, productive cough, and dyspnea on exertion during the previous week. She had traveled to South Africa for 8 weeks and had taken this drug (250 mg orally once a week) as malaria prophylaxis. The therapy was continued for 4 weeks after she returned home. A thorough workup led to the diagnosis of eosinophilic pneumonia due to this drug. Her condition improved after the drug was withdrawn.[Ref]


Frequency not reported: Transient elevation of transaminases

Postmarketing reports: Drug-related hepatic disorders (from asymptomatic transient transaminase elevations to hepatic failure), hepatic failure, hepatitis, jaundice, increased asymptomatic transient transaminases (ALT, AST, GGT)


Frequency not reported: Loss of appetite, anorexia

Postmarketing reports: Decreased appetite[Ref]


Postmarketing reports: Acute renal failure, nephritis, increased blood creatinine


1. Mefloquine for malaria. Med Lett Drugs Ther. 1990;31:13-4.

2. Cerner Multum, Inc. UK Summary of Product Characteristics.

3. Cerner Multum, Inc. Australian Product Information.

4. Caillon E, Schmitt L, Moron P. Acute depressive symptoms after mefloquine treatment. Am J Psychiatry. 1992;149:712.

5. Weinke T, Trautmann M, Held T, et al. Neuropsychiatric side effects after the use of mefloquine. Am J Trop Med Hyg. 1991;45:86-91.

6. Rouveix B, Bricaire F, Michon C, et al. Mefloquine and an acute brain syndrome. Ann Intern Med. 1989;110:577-8.

7. Bem JL, Kerr L, Stuerchler D. Mefloquine prophylaxis: an overview of spontaneous reports of severe psychiatric reactions and convulsions. J Trop Med Hyg. 1992;95:167-79.

8. Bjorkman A. Acute psychosis following mefloquine prophylaxis. Lancet. 1989;2:865.

9. Stuiver PC, Ligthelm RJ, Goud TJ. Acute psychosis after mefloquine. Lancet. 1989;2:282.

10. Harinasuta T, Bunnag D, Wernsdorfer WH. A phase II clinical trial of mefloquine in patients with chloroquine-resistant falciparum malaria in thailand. Bull World Health Organ. 1983;61:299-305.

11. Product Information. Mefloquine Hydrochloride (mefloquine). Hikma USA (formerly West-Ward Pharmaceutical Corporation). 2021.

12. White NJ. Mefloquine. Br Med J. 1994;308:286-7.

13. Speich r, Haller A. Central anticholinergic syndrome with the antimalarial drug mefloquine. N Engl J Med. 1994;331:57-8.

14. Hennequin C, Bouree P, Bazin N, Bisaro F, Feline A. Severe psychiatric side effects observed during prophylaxis and treatment with mefloquine. Arch Intern Med. 1994;154:2360-2.

15. Croft AMJ, World MJ. Neuropsychiatric reactions with mefloquine chemoprophylaxis. Lancet. 1996;347:326.

16. Meszaros K. Acute psychosis caused by mefloquine prophylaxis? Can J Psychiatry. 1996;41:196.

17. Piening RB, Young SA. Mefloquine-induced psychosis. Ann Emerg Med. 1996;27:792-3.

18. Phillips M. Adverse events associated with mefloquine - women may be more susceptible to adverse events. BMJ. 1996;313:1552-3.

19. Overbosch D, Schilthuis H, Bienzle U, et al. Atovaquone-Proguanil versus Mefloquine for Malaria Prophylaxis in Nonimmune Travelers: Results from a Randomized, Double-Blind Study. Clin Infect Dis. 2001;33:1015-21.

20. Van Riemsdijk MM, Ditters JM, Sturkenboom MC, et al. Neuropsychiatric events during prophylactic use of mefloquine before travelling. Eur J Clin Pharmacol. 2002;58:441-5.

21. Jimenez-Huete A, Gil-Nagel A, Franch O. Multifocal myoclonus associated with mefloquine chemoprophylaxis. Clin Neuropharmacol. 2002;25:243.

22. Winstanley P. Malaria: treatment. J R Coll Physicians Lond. 1998;32:203-7.

23. White NJ, Pukrittayakamee S. Clinical malaria in the tropics. Med J Aust. 1993;159:197-203.

24. Brumbaugh M, Price P, Fagan N, Hsieh H. Psychotic mania associated with mefloquine in a bipolar patient. South Med J. 2008;101:550-1.

25. Freedman DO. Clinical practice. Malaria prevention in short-term travelers. N Engl J Med. 2008;359:603-12.

26. Eaton L. Mefloquine has more adverse effects than other drugs for malaria prophylaxis. BMJ. 2009;339:b4167.

27. Yelmo S, Morera-Fumero AL, Henry M, Renshaw A, Gracia-Marco R. Mania associated with mefloquine prophylaxis. J Clin Psychopharmacol. 2010;30:339-41.

28. ter Kuile FO, Nosten F, Thieren M, et al. High-dose mefloquine in the treatment of multidrug-resistant falciparum malaria. J Infect Dis. 1992;166:1393-400.

29. Lobel HO, Bernard KW, Williams SL, et al. Effectiveness and tolerance of long-term malaria prophylaxis with mefloquine: need for a better dosing regimen. JAMA. 1991;265:361-4.

30. De Souza J-M. A phase I clinical trial of mefloquine in brazilian male subjects. Bull World Health Organ. 1983;61:809-14.

31. Ekue JM, Ulrich A-M, Rwabwogo-Atenyi J, Sheth UK. A double-blind comparative clinical trial of mefloquine and chloroquine in symptomatic falciparum malaria. Bull World Health Organ. 1983;61:713-8.

32. Held T, Trautmann M, Weinke T, Mravak S. A prospective clinical trial of the treatment of falciparum malaria with mefloquine, with special reference to neuro-psychiatric side effects. Trans R Soc Trop Med Hyg. 1991;85:444-5.

33. Terkuile FO, Nosten F, Luxemburger C, Kyle D, Tejaisavatharm P, Phaipun L, Price R, Chongsuphajaisiddhi T, White NJ. Mefloquine treatment of acute falciparum malaria: a prospective study of non-serious adverse effects in 3673 patients. Bull World Health Organ. 1995;73:631-42.

34. Bakshi R, Hermeling-Fritz I, Gathmann I, Alteri E. An integrated assessment of the clinical safety of artemether-lumefantrine: a new oral fixed-dose combination antimalarial drug. Trans R Soc Trop Med Hyg. 2000;94:419-24.

35. Singh K, Shanks GD, Wilde H. Seizures after mefloquine. Ann Intern Med. 1991;114:994.

36. Jallon P. Use of mefloquine in epileptic patients. J Neurol Neurosurg Psychiatry. 1988;51:732.

37. Olson PE, Kennedy CA, Morte PD. Paresthesias and mefloquine prophylaxis. Ann Intern Med. 1992;117:1058-9.

38. Gullahorn GM, Bohman HR, Wallace MR. Anaesthesia emergence delirium after mefloquine prophylaxis. Lancet. 1993;341:632.

39. Ruff TA, Sherwen SJ, Donnan GA. Seizure associated with mefloquine for malaria prophylaxis. Med J Aust. 1994;161:453.

40. Choo V. Uncertainty about mefloquine will take time to resolve. Lancet. 1996;347:891.

41. Martin GJ, Malone JL, Ross EV. Exfoliative dermatitis during malarial prophylaxis with mefloquine. Clin Infect Dis. 1993;16:341-2.

42. Scerri L, Pace JL. Mefloquine-associated cutaneous vasculitis. Int J Dermatol. 1993;32:517-8.

43. Australian Government. Department of Health. Therapeutic Goods Administration. Mefloquine hydrochloride (Larium): Safety advisory - potential for visual disturbances. 2013.

44. Kozarsky P, Eaton M. Use of mefloquine for malarial chemoprophylaxis in its first year of availability in the United States. Clin Infect Dis. 1993;16:185-6.

45. Lench P. Malaria prophylaxis - psychological problems after mefloquine and chloroquine. BMJ. 1995;311:192.

46. Terkuile FO, Luxemburger C, Nosten F, Thwai KL, Chongsuphajaisiddhi T, White NJ. Predictors of mefloquine treatment failure: a prospective study of 1590 patients with uncomplicated falciparum malaria. Trans R Soc Trop Med Hyg. 1995;89:660-4.

47. Fonteyne W, Bauwens A, Jordaens L. Atrial flutter with 1:1 conduction after administration of the antimalarial drug mefloquine. Clin Cardiol. 1996;19:967-8.

48. Nosten F, ter Kuile FO, Luxemburger C, et al. Cardiac effects of antimalarial treatment with halofantrine. Lancet. 1993;341:1054-6.

49. Stracher AR, Stoeckle MY, Giordano HF. Aplastic anemia during malarial prophylaxis with mefloquine. Clin Infect Dis. 1994;18:263-4.

50. Fiaccadori E, Maggiore U, Rotelli C, et al. Thrombotic-thrombocytopenic purpura following malaria prophylaxis with mefloquine. J Antimicrob Chemother. 2005;57:160-1.

51. Van Den Eden E, Van Gompel A, Colebunders R, Van Den Ende J. Mefloquine-induced Stevens-Johnson syndrome. Lancet. 1991;337:683.

52. Shlim DR. Severe facial rash associated with mefloquine. JAMA. 1991;266:2560.

53. White AC. Cutaneous vasculitis associated with mefloquine. Ann Intern Med. 1995;123:894.

54. Katsenos S, Psathakis K, Nikolopoulou MI, Constantopoulos SH. Mefloquine-induced eosinophilic pneumonia. Pharmacotherapy. 2007;27:1767-71.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.