Hydroxychloroquine Sulfate

Reviewed on 11/3/2021

What Is Hydroxychloroquine Sulfate and How Does It Work?

Hydroxychloroquine Sulfate is a prescription medication used to treat the symptoms of Malaria, Rheumatoid Arthritis, and Systemic Lupus Erythematosus.

  • Hydroxychloroquine Sulfate is available under the following different brand names: Plaquenil

What Are Dosages of Hydroxychloroquine Sulfate?

Adult and pediatric dosage


  • 200mg



Adult dosage

  • 400 mg (310 mg base) orally weekly, starting 2 weeks before exposure and continued for 4 weeks after departure from endemic area or
  • Weight-based dosing: 6.5 mg/kg (5 mg/kg base) orally once weekly, not to exceed 400 mg (310 mg base), starting 2 weeks before exposure and continued for 4 weeks after leaving the endemic area

Pediatric dosage

  • 6.5 mg/kg (5 mg/kg base) orally once weekly, not to exceed 400 mg (310 mg base), starting 2 weeks before exposure and continued for 4 weeks after leaving the endemic area

Acute treatment

Adult dosage

  • 800 mg (620 mg base) orally, then 400 mg (310 mg base) orally at 6 hours, 24 hours, and 48 hours after initial dose
  • Weight-based dosing: 13 mg/kg (10 mg/kg base), not to exceed 800 mg (620 mg base), followed by 6.5 mg/kg (5 mg/kg base), not to exceed 400 mg (310 mg base), orally at 6 hours, 24 hours, and 48 hours after initial dose

Pediatric dosage

  • 13 mg/kg (10 mg/kg base), not to exceed 800 mg (620 mg base) followed by 6.5 mg/kg (5 mg/kg base), not to exceed 400 mg (310 mg base) orally at 6 hours, 24 hours, and 48 hours after initial dose

Rheumatoid Arthritis

Adult dosage

  • 400-600 mg/day (310-465 mg base/day) orally as once or twice daily

Systemic Lupus Erythematosus

Adult dosage

  • 200-400 mg/day (155-310 mg base/day) orally as a single daily dose or in two divided doses.  
  • Doses exceeding 400 mg/day are not recommended

Dosage Considerations – Should be Given as Follows: 

  • See "Dosages."


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What Are Side Effects Associated with Using Hydroxychloroquine Sulfate?

Common side effects of Hydroxychloroquine Sulfate include:

  • headache, 
  • dizziness, 
  • nausea, 
  • vomiting, 
  • stomach pain, 
  • loss of appetite, 
  • weight loss, 
  • nervousness, 
  • irritableness, 
  • skin rash, 
  • itching, and 
  • hair loss

Serious side effects of Hydroxychloroquine Sulfate include:

  • hives, 
  • difficulty breathing, 
  • swelling of the face, lips, tongue, or throat, 
  • fever, 
  • sore throat, 
  • burning eyes, 
  • skin pain, 
  • red or purple skin rash with blistering and peeling, 
  • fast or pounding heartbeats, 
  • fluttering in the chest, 
  • shortness of breath, 
  • sudden dizziness, 
  • seizure, 
  • unusual mood changes, 
  • severe muscle weakness, 
  • loss of coordination, 
  • underactive reflexes, 
  • chills, 
  • tiredness, 
  • sore throat, 
  • mouth sores, 
  • easy bruising, 
  • unusual bleeding, 
  • pale skin, 
  • cold hands and feet, 
  • lightheadedness
  • shortness of breath, 
  • headache, 
  • hunger, 
  • sweating, 
  • irritability, 
  • dizziness, 
  • fast heart rate, 
  • anxiety, 
  • shakiness, 
  • skin rash, 
  • swollen glands, 
  • muscle aches, 
  • severe weakness, 
  • unusual bruising, 
  • yellowing of the skin or eyes (jaundice), 
  • blurred vision, 
  • trouble focusing, 
  • trouble reading, 
  • distorted vision, 
  • blind spots, 
  • changes in color vision, 
  • hazy or cloudy vision, 
  • seeing light flashes or streaks, 
  • seeing halos around lights, and
  • increased sensitivity to light

Rare side effects of Hydroxychloroquine Sulfate include:

  • none 
This is not a complete list of side effects and other serious side effects or health problems may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Hydroxychloroquine Sulfate?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them.  Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first.

  • Hydroxychloroquine Sulfate has severe interactions with the following drugs:
    • lefamulin 
  • Hydroxychloroquine Sulfate has serious interactions with at least 184 other drugs.
  • Hydroxychloroquine Sulfate has moderate interactions with at least 25 other drugs.
  • Hydroxychloroquine Sulfate has minor interactions with the following drugs: 

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drugs interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use.  Keep a list of all your medications with you, and share this information with your doctor and pharmacist.  Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns.

What Are Warnings and Precautions for Hydroxychloroquine Sulfate?


  • Hypersensitivity to 4-aminoquinoline derivates

Effects of drug abuse

  • None

Short-Term Effects

  • See “What are Side Effects Associated with Using Hydroxychloroquine Sulfate?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Hydroxychloroquine Sulfate?”


  • Not effective against chloroquine-resistant strains of P falciparum
  • Skeletal muscle myopathy or neuropathy leading to progressive weakness and atrophy of proximal muscle groups, depressed tendon reflexes, and abnormal nerve conduction, have been reported
  • Rare suicidal behavior has been reported
  • May cause severe hypoglycemia including loss of consciousness that could be life-threatening in patients treated with or without antidiabetic medications; check blood glucose and adjust treatment if necessary
  • Exercise caution in patients with hepatic disease or alcoholism or in conjunction with known hepatotoxic drugs; a dosage reduction may be necessary in patients with hepatic or renal disease, as well as in those taking medicines known to affect these organs
  • Antimalarial compounds should be used with caution in patients with hepatic disease or alcoholism or in conjunction with known hepatotoxic drugs; perform periodic blood cell counts if patients are given prolonged therapy; if any severe blood disorder (eg, aplastic anemia, agranulocytosis, leukopenia, thrombocytopenia) appears which is not attributable to the disease under treatment, consider discontinuing treatment
  • Use with caution in patients having glucose-6-phosphate dehydrogenase (G-6-PD) deficiency
  • Dermatologic reactions may occur
  • Cardiac effects
    • Postmarketing cases of life-threatening and fatal cardiomyopathy have been reported
    • May present with AV block, pulmonary hypertension, sick sinus syndrome or with cardiac complications
    • ECG findings include atrioventricular, right or left bundle branch block
    • Monitor for signs and symptoms of cardiomyopathy is advised
    • If cardiotoxicity is suspected, promptly discontinue treatment
  • Ocular toxicity
    • Irreversible retinal damage observed; significant risk factors for retinal damage include daily doses of hydroxychloroquine sulfate greater than 6.5 mg/kg (5 mg/kg base) of actual body weight, durations of use >5 years, subnormal glomerular filtration, use of some concomitant drug products such as tamoxifen citrate and concurrent macular disease
    • Recommend an ocular exam within first year of therapy; baseline exam should include: best corrected distance visual acuity (BCVA), an automated threshold visual field (VF) of the central 10 degrees (with retesting if an abnormality is noted), and spectral domain ocular coherence tomography (SD-OCT)
    • In individuals of Asian descent, retinal toxicity may first be noticed outside macula; in patients of Asian descent, perform visual field testing in central 24 degrees instead of central 10 degrees
    • Discontinue if ocular toxicity is suspected and closely observe any retinal changes (and visual disturbances) even after cessation of therapy
  • Drug interaction overview
    • Avoid use with other drugs that have potential to prolong QT interval; hydroxychloroquine prolongs QT interval; ventricular arrhythmias and torsades de pointes reported in patients taking hydroxychloroquine
    • Concomitant use with hydroxychloroquine and digoxin therapy may result in increased serum digoxin levels: closely monitor serum digoxin levels in patients receiving combined therapy
    • May enhance the effects of a hypoglycemic treatment, a decrease in doses of insulin or antidiabetic drugs may be required
    • Coadministration with other antimalarials known to lower the convulsion threshold (eg, mefloquine) may increase the risk of convulsions
    • Activity of antiepileptic drugs might be impaired if coadministered with hydroxychloroquine
    • An increased plasma cyclosporine level was reported when cyclosporine and hydroxychloroquine were coadministered

Pregnancy and Lactation

  • There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to drug during pregnancy; encourage patients to register by contacting 1-877-311-8972
  • Prolonged clinical experience over decades of use and available data from published epidemiologic and clinical studies with use in pregnant women have not identified a drug-associated risk of major birth defects, miscarriage, or adverse maternal, or fetal outcomes
  • There are risks to mother and fetus associated with untreated or increased disease activity from malaria, rheumatoid arthritis, and systemic lupus erythematosus in pregnancy
  • Animal reproduction studies were not conducted with hydroxychloroquine
  • Clinical considerations
    • Malaria during pregnancy increases risk for adverse pregnancy outcomes, including maternal anemia, prematurity, spontaneous abortion, and stillbirth
    • Published data on rheumatoid arthritis suggest that increased disease activity is associated with the risk of developing adverse pregnancy outcomes in women with rheumatoid arthritis include preterm delivery (before 37 weeks of gestation), low birth weight (less than 2500 g) infants, and small for gestational age at birth
    • Pregnant women with systemic lupus erythematosus, especially those with increased disease activity, are at increased risk of adverse pregnancy outcomes, including spontaneous abortion, fetal death, preeclampsia, preterm birth, and intrauterine growth restriction; passage of maternal auto-antibodies across placenta may result in neonatal illness, including neonatal lupus and congenital heart block
    • Embryonic deaths and malformations of anophthalmia and microphthalmia in the offspring have been reported when pregnant rats received large doses of chloroquine
  • Lactation
    • Exercise caution when administering hydroxychloroquine to nursing women
    • Published lactation data report that hydroxychloroquine is present in human milk at low levels; no adverse reactions have been reported in breastfed infants; no retinal toxicity, ototoxicity, cardiotoxicity, or growth and developmental abnormalities observed in children exposed to hydroxychloroquine through breastmilk
    • There is no information on effect of hydroxychloroquine on milk production; developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for therapy and any potential adverse effects on breastfed child from drug or from underlying maternal condition
    • When administered to nursing women, hydroxychloroquine is excreted in human milk and it is known that infants are extremely sensitive to the toxic effects of 4-aminoquinolines


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