Hydroxychloroquine Sulfate
Pronunciation: hye-DROX-ee-KLOR-oh-kwin.
- Generic name
- hydroxychloroquine sulfate
- Brand names
- Hydroquin, Hydroxychloroquine Sandoz, Hydroxychloroquine GH, HCQS, Quinoric, Plaquenil
- Drug class
- Antimalarial, Disease-Modifying Antirheumatic Drug (DMARD)
Availability and supply rules vary by country
Trade names by country: United States · Canada
Australia: · Full directory
What hydroxychloroquine sulfate is and how it works
Uses, formulations, monitoring, and supply rules can differ by patient, product, and country. Follow the exact local product information and professional advice.
Mechanism of action: how hydroxychloroquine sulfate works
Hydroxychloroquine increases the pH within intracellular vacuoles, interfering with lysosomal activity and autophagy. It inhibits antigen processing and presentation, modulates immune cell signaling, and reduces cytokine production. In malaria, it disrupts the parasite's ability to metabolize and utilize erythrocyte hemoglobin. (1)
What hydroxychloroquine sulfate is used for
Malaria treatment and prophylaxis
Malaria treatment and prophylaxis (2)
Rheumatoid arthritis
Rheumatoid arthritis (2)
Systemic lupus erythematosus
Systemic lupus erythematosus (2)
Sjögren's syndrome (off-label use)
CORRECTED: the FDA label for hydroxychloroquine covers malaria, rheumatoid arthritis, and systemic/discoid lupus erythematosus only. Sjögren's syndrome is not an FDA-approved indication; use for this condition is off-label, though it is a real and reasonably common clinical practice. (2)
Before taking hydroxychloroquine sulfate
Do not take / not appropriate for
- Contraindicated in patients with known hypersensitivity to hydroxychloroquine or related compounds, pre-existing retinopathy, or visual field changes. (Contraindication) (2)
Tell your clinician about
(2)How to take hydroxychloroquine sulfate
- General Instructions: Take hydroxychloroquine exactly as prescribed by your healthcare provider. Do not take more or less than directed. Swallow tablets whole with a meal or a glass of milk to reduce stomach upset.. Adult Dosing: For rheumatoid arthritis or lupus: 200–400 mg orally once daily or divided into two doses. For malaria prophylaxis: 400 mg once weekly, starting 1–2 weeks before exposure and continuing for 4 weeks after leaving the area.. Pediatric Dosing: Dosing in children is based on body weight and indication. For malaria prophylaxis: 6.5 mg/kg (maximum 400 mg) once weekly. Always follow pediatric specialist guidance.. Administration: Take with food or milk to minimize gastrointestinal upset. Do not crush or chew tablets unless advised by your doctor.. When To Stop: Do not stop taking hydroxychloroquine suddenly without consulting your healthcare provider, as abrupt discontinuation may worsen your condition.. Storage: Store at room temperature, away from moisture, heat, and direct light. Keep out of reach of children.
- This page does not provide a dose calculator. Dosing must follow the prescriber, pharmacist, or product label.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (2)
Missed dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and resume your regular schedule. Do not take an extra dose to catch up.
Overdose
Overdose can be life-threatening, especially in children. Symptoms may include headache, drowsiness, vision changes, seizures, irregular heartbeat, or fainting. Seek emergency medical attention or call your local poison control center immediately. (2)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms to a healthcare professional.
Nausea
Incidence: Reported in the clinician-authored database; frequency not established
Diarrhea
Incidence: Reported in the clinician-authored database; frequency not established
Stomach cramps
Incidence: Reported in the clinician-authored database; frequency not established
Rash
Incidence: Reported in the clinician-authored database; frequency not established
Headache
Incidence: Reported in the clinician-authored database; frequency not established
Blurred vision
Incidence: Reported in the clinician-authored database; frequency not established
Retinopathy
Incidence: Reported in the clinician-authored database; frequency not established
Cardiomyopathy
Incidence: Reported in the clinician-authored database; frequency not established
Vision changes: missing words/letters when reading, sensitivity to light, blurred distance vision, blacked-out areas of vision, or light flashes/streaks — possible retinal toxicity
(2)Palpitations, fainting, or signs of heart failure (swelling, shortness of breath) — possible cardiotoxicity
(2)Signs of low blood sugar if also taking insulin or other diabetes medicines
(2)Serious warnings
May cause irreversible retinal damage — serious
Symptoms: May cause irreversible retinal damage; regular eye exams are required. Use with caution in patients with heart rhythm disorders (QT prolongation risk). May worsen psoriasis or porphyria. Not recommended for long-term use in children. Use during pregnancy only if clearly needed and prescribed by a doctor.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Contraindications recorded in the clinician database — serious
Symptoms: Contraindications recorded in the clinician database: Contraindicated in patients with known hypersensitivity to hydroxychloroquine or related compounds, pre-existing retinopathy, or visual field changes. Use with caution in patients with hepatic or renal impairment, cardiac arrhythmias (especially QT prolongation), psoriasis, porphyria, and G6PD deficiency.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
The FDA label adds detail beyond the clinician database — serious
Symptoms: The FDA label adds detail beyond the clinician database: retinopathy risk rises with daily doses above 5 mg/kg of actual body weight, and with cumulative dose/treatment duration — this dosing threshold is a key reason doses are individualized and monitored rather than fixed. Fatal and life-threatening cardiotoxicity, including cardiomyopathy, has been reported; the drug can prolong the QT interval, so it should be avoided in patients with congenital QT prolongation or when combined with other QT-prolonging drugs.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Recorded interactions | Hydroxychloroquine may interact with other medications, including digoxin, antiepileptics, antidiabetic agents, cyclosporine, and drugs that prolong the QT interval (such as certain antiarrhythmics and antibiotics). Always inform your healthcare provider about all medicines and supplements you are taking. | (1) |
| Insulin and other antidiabetic agents | Hydroxychloroquine can enhance the blood-sugar-lowering effect, increasing hypoglycemia risk, per FDA labeling; dose adjustment of the diabetes medicine may be needed by your prescriber. | (2) |
| Methotrexate | May increase the risk of methotrexate-related adverse reactions, per FDA labeling. | (2) |
| Digoxin and cyclosporine | Hydroxychloroquine can raise blood levels of both, per FDA labeling, requiring closer monitoring by your prescriber. | (2) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Decades of clinical experience with hydroxychloroquine, per the FDA label, have not identified a drug-associated risk of major birth defects. It is used during pregnancy under close medical supervision, particularly for lupus and rheumatoid arthritis, when the benefits are judged to outweigh the risks by your prescriber. (2)
Breastfeeding
Hydroxychloroquine is present in breast milk at low levels; the FDA label notes no adverse effects have been reported in breastfed infants. Discuss breastfeeding with your healthcare provider. (2)
Children
Frequency: Not recommended for pediatric use.. Weight Based: Not established for pediatric use.. Max Daily Dose: Not recommended for pediatric use.. Max Single Dose: Not recommended for pediatric use.. Age Restrictions: Safety not established in children. Note: malaria prophylaxis dosing in children (6.5 mg/kg, max 400 mg, once weekly) is recorded elsewhere in this record for that specific use, under specialist guidance. (2)
Renal_impairment
The FDA label notes a dose reduction may be necessary in patients with hepatic or renal disease; the exact adjustment is individualized by the treating clinician, as no fixed reduced-dose regimen is specified in the sources reviewed. (2)
Hepatic_impairment
The FDA label notes a dose reduction may be necessary in patients with hepatic or renal disease; the exact adjustment is individualized by the treating clinician, as no fixed reduced-dose regimen is specified in the sources reviewed. (2)
Monitoring
(2)Storage
Store at room temperature, up to 30°C (86°F), in a tight, light-resistant container, away from moisture and direct light. Keep out of reach of children.
Professional information
Clinician-facing context only. This section does not replace current product labeling.
General
Indication: Malaria treatment and prophylaxis / RA / lupus (dosing individualized to stay under the retinopathy-risk threshold)
Dose summary: Malaria treatment: initial 400 mg on day 1, then 200 mg once daily. RA: 400-600 mg/day initially, maintenance 200-400 mg/day. Lupus/discoid lupus: 200-400 mg/day. FDA labeling: daily doses above 5 mg/kg actual body weight increase retinopathy risk.
Renal context: A dose reduction may be necessary in renal or hepatic impairment, individualized by the treating clinician; no fixed reduced-dose regimen is specified in either source reviewed. (1) (2)
Frequently asked questions
What conditions does hydroxychloroquine treat?
Hydroxychloroquine is used to prevent and treat malaria, and to manage autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus.
How long does it take for hydroxychloroquine to work for arthritis or lupus?
It may take several weeks to months for the full benefits to be seen in autoimmune conditions. Continue taking as prescribed and consult your doctor if you have concerns.
Is hydroxychloroquine safe during pregnancy?
Decades of clinical experience have not identified a drug-associated risk of major birth defects, per the FDA label. It may be used during pregnancy if the benefits outweigh the risks, but only under close medical supervision.
Do I need regular eye exams while taking hydroxychloroquine?
Yes, regular eye exams are recommended before starting and periodically during treatment to monitor for retinal toxicity.
Can hydroxychloroquine be used for COVID-19?
Hydroxychloroquine is not recommended for the prevention or treatment of COVID-19 outside of clinical trials, as studies have not shown clear benefit and there are safety concerns.
What should I do if I experience vision changes?
Contact your healthcare provider immediately if you notice any changes in vision, as this may indicate serious side effects.
Can children take hydroxychloroquine?
Hydroxychloroquine can be prescribed to children for certain conditions, but dosing must be carefully calculated and monitored by a pediatric specialist.
What happens if I take too much Hydroxychloroquine?
Taking too much Hydroxychloroquine can lead to serious and potentially life-threatening symptoms, including cardiac arrhythmias, seizures, and respiratory depression. If an overdose is suspected, it is crucial to seek immediate emergency medical attention. Do not attempt to induce vomiting or self-treat. Prompt professional intervention is essential for managing overdose.
Can I drink alcohol while taking Hydroxychloroquine?
While there isn't a strict contraindication against moderate alcohol consumption with Hydroxychloroquine, it's generally advisable to limit or avoid alcohol. Both alcohol and Hydroxychloroquine can be metabolized by the liver, and excessive alcohol intake may increase the risk of liver-related side effects or exacerbate gastrointestinal issues. Always discuss alcohol consumption with your healthcare provider.
What is the mechanism of action of hydroxychloroquine sulfate?
Hydroxychloroquine increases the pH within intracellular vacuoles, interfering with lysosomal activity and autophagy. It inhibits antigen processing and presentation, modulates immune cell signaling, and reduces cytokine production. In malaria, it disrupts the parasite's ability to metabolize and utilize erythrocyte hemoglobin. (1)
What is the generic name of Hydroxychloroquine Sulfate?
The generic name is hydroxychloroquine sulfate. It is sold under brand names including Hydroquin, Hydroxychloroquine Sandoz, Hydroxychloroquine GH, HCQS, Quinoric, Plaquenil.
What class of drug is hydroxychloroquine sulfate?
Hydroxychloroquine Sulfate is classed as: Antimalarial, Disease-Modifying Antirheumatic Drug (DMARD).
References
- MedGuideGlobal Clinician-Authored Medicine Record: HydroxychloroquineMedGuideGlobal · Global (internal clinician-authored record) · accessed 2026-08-06 · source 1
- PLAQUENIL (hydroxychloroquine sulfate) tablets prescribing informationU.S. Food and Drug Administration (DailyMed) · United States · accessed 2026-08-06 · source 2
- HYDROXYCHLOROQUINE SULFATE TABLET, FILM COATED [MAJOR PHARMACEUTICALS] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
- Hydroxychloroquine — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 4
- HYDROXYCHLOROQUINE SULFATE — FDA approval record (Drugs@FDA ANDA040150)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 5
- hydroxychloroquine — RxNorm normalized drug concept (RXCUI 153972)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 6
Brand names by country
Single-ingredient hydroxychloroquine sulfate names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- Plaquenil200 mg · aphena pharma solutions - tennessee, llc
- SOVUNA300 mg, 200 mg · ani pharmaceuticals, inc.
Canada
- PLAQUENIL
- APO-HYDROXYQUINE
- PRO-HYDROXYQUINE -