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Qualaquin Side Effects

Generic name: quinine

Medically reviewed by Last updated on Jan 7, 2023.

Note: This document contains side effect information about quinine. Some dosage forms listed on this page may not apply to the brand name Qualaquin.

Applies to quinine: oral capsule.


Oral route (Capsule)

Quinine sulfate use for the treatment or prevention of nocturnal leg cramps may result in serious and life-threatening hematologic reactions, including thrombocytopenia and hemolytic uremic syndrome/thrombotic thrombocytopenic purpura (HUS/TTP). Chronic renal impairment associated with the development of TTP has been reported. The risk associated with quinine sulfate use in the absence of evidence of its effectiveness in the treatment or prevention of nocturnal leg cramps outweighs any potential benefit.

Serious side effects of Qualaquin

Along with its needed effects, quinine (the active ingredient contained in Qualaquin) 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 quinine:

More common

  • Blurred vision
  • change in color vision
  • changes in behavior
  • confusion
  • diarrhea
  • hearing loss
  • nausea
  • ringing in the ears
  • stomach cramps or pain
  • vomiting

Less common

  • Anxiety
  • behavior change, similar to drunkenness
  • black, tarry stools
  • bloody urine
  • blurred vision or change in vision
  • chills
  • cold sweats
  • confusion
  • cool pale skin
  • cough
  • difficulty concentrating
  • drowsiness
  • excessive hunger
  • fast heartbeat
  • fever
  • headache
  • hoarseness
  • loss of consciousness
  • lower back or side pain
  • nervousness
  • nightmares
  • painful or difficult urination
  • pinpoint red spots on the skin
  • restless sleep
  • seizures
  • shakiness
  • slurred speech
  • sore throat
  • unusual bleeding or bruising
  • unusual tiredness or weakness


  • Difficulty breathing or swallowing
  • disturbed color perception
  • double vision
  • hives
  • increased sweating
  • muscle aches
  • night blindness
  • reddening of the skin, especially around ears
  • ringing or buzzing in the ears
  • swelling of the eyes, face, inside of the nose, fingers, feet, or lower legs

Incidence not known

  • Back, leg, or stomach pains
  • bleeding gums
  • bleeding under the skin
  • blindness
  • blistering, peeling, or loosening of the skin
  • bloody nose
  • blue-yellow color blindness
  • change in mental status
  • chest pain
  • cold sweats
  • confusion
  • cool, pale skin
  • cough
  • dark urine
  • decreased frequency or amount of urine
  • decreased vision
  • depression
  • diarrhea
  • difficulty breathing
  • difficulty in moving
  • difficulty speaking
  • dizziness
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • eye pain
  • fainting
  • fast, pounding, or irregular heartbeat or pulse
  • general body swelling
  • general feeling of discomfort, illness, or weakness
  • hoarseness
  • heavier menstrual periods
  • hoarseness
  • increased hunger
  • increased or decreased urination
  • increased sensitivity of the skin to sunlight
  • increased thirst
  • irregular heartbeat, recurrent
  • irritation
  • itching, skin rash
  • joint pain, stiffness, or swelling
  • light-colored stools
  • loss of appetite
  • muscle cramps, weakness, or stiffness
  • nervousness
  • nightmares
  • nosebleeds
  • painful or difficult urination
  • pale color of the skin
  • pale skin
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • redness or other discoloration of the skin
  • severe
  • sunburn
  • sores, ulcers, or white spots in the mouth or on the lips
  • tightness in the chest
  • troubled swallowing
  • upper right abdominal pain
  • weakness
  • weight gain
  • yellow eyes or skin

Get emergency help immediately if any of the following symptoms of overdose occur while taking quinine:

Symptoms of an overdose

  • Blindness
  • blurred vision or change in vision
  • chest pain
  • dizziness
  • double vision
  • fainting
  • lightheadedness
  • rapid or irregular heartbeat
  • sleepiness

Other side effects of Qualaquin

Some side effects of quinine 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:

Incidence not known

  • Feeling of warmth
  • heartburn
  • lack or loss of strength
  • pain or burning in the throat
  • problems with speech or speaking
  • restlessness
  • thoughts or attempts of killing oneself tremors
  • unsteadiness, trembling, or other problems with muscle control or coordination
  • weight loss

For Healthcare Professionals

Applies to quinine: compounding powder, oral capsule, oral tablet.


This drug adversely affected almost all body systems. The most common side effects associated with this drug were a cluster of symptoms (cinchonism) which occurred to some degree in almost all patients using this drug.[Ref]


Disseminated intravascular coagulation has been reported in a 79-year-old female within 12 hours after a second 300 mg dose.[Ref]

Frequency not reported: Agranulocytosis, hypoprothrombinemia, thrombocytopenia (including fatal cases), hemolytic anemia, neutropenia, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, disseminated intravascular coagulation, idiopathic thrombocytopenic purpura, petechiae, ecchymosis, hemorrhage, coagulopathy, blackwater fever, leukopenia, pancytopenia, aplastic anemia, lupus anticoagulant, hemolysis (including acute), thrombocytopenic purpura, intravascular coagulation, immune thrombocytopenia, purpura[Ref]


Fixed drug eruption (nummular skin lesion) has been reported in a 23-year-old female after exposure to quinine (the active ingredient contained in Qualaquin) in tonic water. An open oral challenge (patient approved) with 30 mg quinine sulfate triggered the appearance of pruritus, erythema, and edema at the usual sites within 40 minutes of ingesting the dose.[Ref]

Frequency not reported: Cutaneous rashes (including urticarial, papular, scarlatinal), pruritus, bullous dermatitis, exfoliative dermatitis, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, rashes, fixed drug eruption (nummular skin lesion), photosensitivity reactions, allergic contact dermatitis, acral necrosis, cutaneous vasculitis (including fatal cases), urticaria, angioedema, eczematous dermatitis, erythema, lichen planus[Ref]


Frequency not reported: Nausea, vomiting, diarrhea, abdominal pain, gastric irritation, esophagitis, epigastric pain, gastrointestinal upset[Ref]


Frequency not reported: Renal failure (including secondary to thrombotic thrombocytopenic purpura-hemolytic uremic syndrome), renal impairment/insufficiency, acute renal failure (due to immune mechanism or circulatory failure), acute interstitial nephritis, anuria, uremia, oliguria[Ref]


Frequency not reported: Asthma, dyspnea, pulmonary edema, asthma precipitation, asthmatic symptoms, bronchospasm, hemoptysis, transient bilateral pulmonary infiltrates[Ref]

Transient bilateral pulmonary infiltrates have been reported in a 45-year-old woman following a single 325 mg dose for nocturnal cramps. About 45 minutes after taking the dose, the following symptoms were present: sudden onset of dyspnea, wheezing, cough, breathlessness, severe anxiety, dry nonproductive cough, orthopnea, mild fever, chills, and pleuritic chest discomfort.[Ref]


Frequency not reported: Diplopia, visual disturbances, blurred vision with scotomata, sudden loss of vision, photophobia, night blindness, diminished/constricted visual fields, fixed pupillary dilatation, disturbed color vision/perception, optic neuritis, blindness, mydriasis, optic atrophy, blurred vision, defective color perception, nystagmus[Ref]


Frequency not reported: Chest pain, vasodilatation, hypotension, tachycardia, bradycardia, palpitations, atrioventricular block, atrial fibrillation, irregular rhythm, unifocal premature ventricular contractions, nodal escape beats, U waves, QT prolongation, ventricular fibrillation, ventricular tachycardia, torsade de pointes, cardiac arrest, disturbance in cardiac rhythm/conduction, widening of QRS complex, angina symptoms, cardiovascular toxicity, atrioventricular conduction disturbances, fall in blood pressure with feeble pulse, T wave flattening, cardiac dysrhythmias[Ref]

Angina symptoms have been reported with prolonged therapy in sensitive patients.

Severe cardiovascular toxicity has been reported with rapid IV administration; fatal cases reported.[Ref]


Within 24 hours of taking the first 260 mg dose for leg cramps, a 57-year-old Native American female presented to the hospital with symptoms of nausea, vomiting, generalized myalgia, headache, fever, chills, and rigor. The following liver enzymes were dramatically elevated: alkaline phosphatase, lactate dehydrogenase, AST, ALT, and GGT. After stopping this drug, the patient's symptoms resolved within 48 hours and the liver enzyme levels declined within 72 hours.[Ref]

Frequency not reported: Granulomatous hepatitis, hepatitis, jaundice, abnormal liver function tests, changes in the hepatic enzyme system that synthesizes vitamin K-dependent factors, hepatotoxicity, elevated alkaline phosphatase, elevated lactate dehydrogenase, elevated AST, elevated ALT, elevated GGT[Ref]

Nervous system

Frequency not reported: Headache, seizures, coma, tremors, restlessness, ataxia, acute dystonic reaction, aphasia, syncope, vertigo, tinnitus, hearing impairment, deafness, loss of consciousness, dizziness, hearing loss[Ref]


Frequency not reported: Hypersensitivity reactions (included asthma, angioneurotic edema, photosensitivity, hot and flushed skin, fever, pruritus, thrombocytopenic purpura, urticaria)[Ref]


Frequency not reported: Hypoglycemia, anorexia, hypoglycemia aggravated, electrolyte imbalance[Ref]


Symptoms of mild cinchonism included headache, vasodilation and sweating, nausea, tinnitus, hearing impairment, vertigo/dizziness, blurred vision, and disturbance in color perception; more severe symptoms of cinchonism were vomiting, diarrhea, abdominal pain, deafness, blindness, and disturbances in cardiac rhythm/conduction. Most symptoms of cinchonism were reversible and resolved with discontinuation of this drug.[Ref]

Frequency not reported: Cinchonism (included deafness, tinnitus, headache, vasodilation and sweating, hearing impairment, rashes, vertigo/dizziness, blurred/disturbed vision, defective/disturbance in color perception, vomiting, diarrhea, abdominal pain, gastrointestinal symptoms, oculotoxicity, central nervous system disturbances, visual field constriction, blindness, nausea, disturbances in cardiac rhythm/conduction, cardiotoxicity, death), fever, chills, sweating, flushing, asthenia, facial edema, death, mucosal bleeding (gingival, gastrointestinal, epistaxis)[Ref]


Frequency not reported: Lupus-like syndrome, myalgias, muscle weakness, myasthenia gravis aggravated, decreased neuromuscular transmission by increasing excitability threshold at myoneural junction, depressed muscle action potential


Frequency not reported: Confusion, altered mental status, disorientation, suicide, apprehension, agitation


Frequency not reported: Hemoglobinuria, abortion[Ref]


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19. Krantz MJ, Dart RC, Mehler PS. Transient pulmonary infiltrates possibly induced by quinine sulfate. Pharmacotherapy. 2002;22:775-8.

20. Feeney GFX, Lee GA, OConnor PA. Quinine-induced blindness during attempted heroin withdrawal. Med J Australia. 1999;170:449.

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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.