hydroxychloroquine
Brand names: Plaquenil
Hydroxychloroquine is a drug used to treat or prevent malaria, and to treat certain autoimmune diseases. It works by interfering with the immune system and by killing malaria parasites.
Drug Shortage Alert
hydroxychloroquine is currently listed as to be discontinued by the FDA. Affected manufacturer: Teva Pharmaceuticals USA, Inc..
View all drug shortages →Drug Pricing (NADAC)
Generic Price
$0.17/unit
Generic Available
Yes (11 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
This medicine can treat uncomplicated malaria caused by certain parasites.
Common side effects
Nausea, Vomiting, Diarrhea
Key warnings
This drug can cause heart problems, including a weakened heart muscle and irregular heartbeats.
How It Works
Hydroxychloroquine is an antimalarial and antirheumatic drug. It is thought to work by interfering with the immune system's activity. It also stops the growth of malaria parasites in red blood cells.
How to Take It
Take this medicine by mouth with food or milk. Do not crush or divide the tablets. For malaria prevention, start taking it 2 weeks before traveling to an area with malaria. Continue taking it weekly while you are there and for 4 weeks after you leave.
Pregnancy & Breastfeeding
Tell your doctor if you are pregnant or plan to become pregnant. This drug can cross the placenta, but studies haven't shown a risk of major birth defects. Talk to your doctor about the risks and benefits of taking this medicine while pregnant. Hydroxychloroquine passes into breast milk. Talk to your doctor about breastfeeding while taking this medicine.
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 continue with your regular schedule.
Storage
Store at room temperature, away from light and moisture.
Side Effects (from patient reports)
Based on 109,112 FDA adverse event reports.
FDA Adverse Event Report Analysis
Detailed analysis of 71,900 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
71,900
Death-Related Reports
7,814
Hospitalization Reports
20,530
Top Indication
Rheumatoid Arthritis
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | DRUG INEFFECTIVE | 20,457 |
| 2 | OFF LABEL USE | 15,128 |
| 3 | RHEUMATOID ARTHRITIS | 12,921 |
| 4 | PAIN | 10,409 |
| 5 | ARTHRALGIA | 9,276 |
| 6 | DRUG INTOLERANCE | 9,157 |
| 7 | FATIGUE | 8,853 |
| 8 | JOINT SWELLING | 8,528 |
| 9 | RASH | 7,370 |
| 10 | CONDITION AGGRAVATED | 7,013 |
| 11 | SYNOVITIS | 6,692 |
| 12 | NAUSEA | 6,584 |
| 13 | CONTRAINDICATED PRODUCT ADMINISTERED | 6,430 |
| 14 | TREATMENT FAILURE | 6,014 |
| 15 | ALOPECIA | 5,939 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
This drug can cause heart problems, including a weakened heart muscle and irregular heartbeats. It can also cause irreversible damage to your retina, so regular eye exams are needed. This medicine can also cause serious skin reactions. If you have psoriasis or porphyria, talk to your doctor before taking this medicine. It can also cause liver and kidney problems.
Known Drug Interactions
( 7 ) 7.1 Drugs Prolonging QT Interval and Other Arrhythmogenic Drugs Hydroxychloroquine sulfate tablets prolongs the QT interval. There may be an increased risk of inducing ventricular arrhythmias if hydroxychloroquine sulfate tablets are used concomitantly with other arrhythmogenic drugs. Therefore, hydroxychloroquine sulfate tablets are not recommended in patients taking other drugs that have the potential to prolong the QT interval or are arrhythmogenic [see Warnings and Precautions (5.1) ].
Mechanism: Both of these drugs can change the electrical rhythm of your heart. Taking them together increases the risk of a dangerous irregular heartbeat.
What to do: This combination is not recommended. Talk to your doctor about using a different medication to avoid heart rhythm problems.
7.8 Cimetidine Concomitant use of cimetidine resulted in a 2-fold increase of exposure of chloroquine, which is structurally related to hydroxychloroquine. Interaction of cimetidine with hydroxychloroquine cannot be ruled out. Avoid concomitant use of cimetidine.
Mechanism: Cimetidine can slow down how your body breaks down hydroxychloroquine, which can double the amount of the drug in your system. This makes side effects much more likely.
What to do: Avoid taking these two medications together. Ask your doctor for an alternative to cimetidine.
7.2 Platelet Inhibitors Drugs such as NSAIDS (including salicylic acid, ibuprofen, indomethacin, and celecoxib), dextran, phenylbutazone, thienopyridines, dipyridamole, hydroxychloroquine, glycoprotein IIb/IIIa antagonists (including abciximab, eptifibatide, and tirofiban), and others that interfere with platelet-aggregation reactions (the main hemostatic defense of heparinized patients) may induce bleeding and should be used with caution in patients receiving heparin sodium.
Mechanism: Hydroxychloroquine can interfere with how blood cells stick together to stop bleeding. When taken with a blood thinner like heparin, it increases the chance of serious bleeding.
What to do: Use this combination with caution. Be sure to report any unusual bleeding or bruising to your doctor right away.
7 DRUG INTERACTIONS 7.1 Effects of Other Drugs on VEKLURY Due to potential antagonism based on data from cell culture experiments, concomitant use of VEKLURY with chloroquine phosphate or hydroxychloroquine sulfate is not recommended [see Warnings and Precautions (5.3) and Microbiology (12.4) ].
Mechanism: Hydroxychloroquine can interfere with how remdesivir works against the virus. This means the antiviral treatment might not be able to fight the infection effectively.
What to do: This combination is not recommended. Your healthcare provider should avoid giving you these two drugs at the same time.
7.5 Methotrexate Concomitant use of hydroxychloroquine sulfate tablets and methotrexate may increase the incidence of adverse reactions.
Mechanism: Using these two medications at the same time can make it more likely that you will experience side effects.
What to do: Your doctor may need to watch you more closely for any new or worsening symptoms while you are on both drugs.
Common Questions
What should I do if I experience vision changes while taking this medication?
Can I take this medication with other medications?
How long does it take for this medication to start working for rheumatoid arthritis?
Can this medication cure lupus?
What should I do if I develop a rash while taking this medication?
Is it safe to drink alcohol while taking this medication?
Can this medication affect my blood sugar?
Will this medication protect me from all types of malaria?
Can I stop taking this medication if I feel better?
Are there any long-term side effects I should be aware of?
What are the common side effects of hydroxychloroquine?
Does hydroxychloroquine interact with other medications?
What drug class is hydroxychloroquine?
Is hydroxychloroquine safe during pregnancy?
Is hydroxychloroquine currently in shortage?
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What the FDA Data Shows for hydroxychloroquine
The FDA label for hydroxychloroquine (sold under brand names such as Plaquenil) classifies it as a prescription-only medication in the Disease-Modifying Antirheumatic Drug (DMARD) class. This medicine can treat uncomplicated malaria caused by certain parasites. Official labeling lists 6 commonly reported side effects, including Nausea, Vomiting, Diarrhea.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 109,112 voluntary reports. The database also lists 7 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated moderate severity. NADAC pricing from CMS shows a generic unit cost of $0.17.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC). Shortage status: FDA Drug Shortages Database.
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: October 9, 2025
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages