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Mefloquine Side Effects

Medically reviewed by Last updated on March 16, 2020.

For the Consumer

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

Side effects requiring immediate medical attention

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:


  • Aching joints and muscles
  • anxiety
  • blistering, loosening, peeling, or redness of the skin
  • chest pain or discomfort
  • chills
  • confusion
  • convulsions (seizures)
  • cough or hoarseness
  • dizziness
  • fainting
  • fever
  • hallucinations (seeing, hearing, or feeling things that are not there)
  • irregular, pounding, slow, or fast heartbeat or pulse
  • irritability
  • lightheadedness
  • lower back or side pain
  • mental depression
  • painful or difficult urination
  • pinpoint red spots on the skin
  • red or irritated eye
  • restlessness
  • sore throat
  • sores, ulcers, or white spots in the mouth or on the lips
  • stiff neck
  • swelling of the ankles, feet, or lower legs
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • vomiting

Incidence not known

  • Blurred or loss of vision
  • continuing ringing or buzzing or other unexplained noise in the ears
  • disturbed color perception
  • double vision
  • feeling of constant movement of self or surroundings
  • halos around lights
  • hearing loss
  • hearing problems
  • loss of balance
  • loss of bladder control
  • muscle spasm or jerking of all extremities
  • night blindness
  • overbright appearance of lights
  • sensation of spinning
  • severe or continuing headache
  • sudden loss of consciousness
  • trouble sleeping
  • troubled breathing
  • tunnel vision

Side effects not requiring immediate medical attention

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


  • Loss of hair

Incidence not known

  • Acid or sour stomach
  • belching
  • flushing or redness of the skin
  • heartburn
  • indigestion
  • skin rash with a general disease
  • stomach discomfort, upset, or pain
  • swelling
  • unusually warm skin

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


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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.