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pronounced as (hye drox ee klor' oh kwin)

Why is this medication prescribed?

Hydroxychloroquine is used to prevent and treat acute attacks of malaria in adults and children weighing more than 31 kg (68 lbs). It is also used to treat discoid lupus erythematosus (DLE; a chronic inflammatory condition of the skin) or systemic lupus erythematosus (SLE or lupus; an autoimmune disease in which the immune system attacks healthy parts of the body such as joints, skin, blood vessels, and organs) and rheumatoid arthritis. Hydroxychloroquine is in a class of drugs called antimalarials and is also an antirheumatic drug. It works by killing the organisms that cause malaria. Hydroxychloroquine may work to treat rheumatoid arthritis and systemic lupus erythematosus by decreasing the activity of the immune system.

How should this medicine be used?

Hydroxychloroquine comes as a tablet to take by mouth. Hydroxychloroquine tablets should be taken with food or milk. If you are taking hydroxychloroquine to prevent malaria, one dose is usually taken once a week on exactly the same day of each week. You will begin treatment 1 to 2 weeks before you travel to an area where malaria is common and then continue during your time in the area and for 4 weeks after you return. If you are taking hydroxychloroquine to treat malaria, the first dose is usually taken right away, followed by another dose 6 hours later and then 2 additional doses, 24 and 48 hours after the first dose. If you are taking hydroxychloroquine to treat lupus erythematosus (DLE or SLE) or rheumatoid arthritis, it is usually taken once or twice a day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take hydroxychloroquine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Swallow the tablets whole; do not split, chew, or crush them.

If you are taking hydroxychloroquine for symptoms of rheumatoid arthritis, your symptoms should improve within several weeks to months. If your rheumatoid arthritis symptoms do not improve, or if they worsen, call your doctor. Once you and your doctor are sure the drug works for you, do not stop taking hydroxychloroquine without talking to your doctor. Symptoms of rheumatoid arthritis will return if you stop taking hydroxychloroquine.

Other uses for this medicine

Hydroxychloroquine is also sometimes used to treat porphyria cutanea tarda (condition in which certain natural substances build up in the body and may cause painful, blistering skin due to sensitivity to sunlight). Hydroxychloroquine has also been studied for the treatment and prevention of coronavirus disease 2019 (COVID-19).Talk to your doctor about the possible risks of using this drug for your condition.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

What special precautions should I follow?

Before taking hydroxychloroquine,

  • tell your doctor and pharmacist if you are allergic to hydroxychloroquine, chloroquine, primaquine, quinine, any other medications, or any of the ingredients in hydroxychloroquine tablets. Ask your pharmacist for a list of the ingredients.
  • tell your doctor and pharmacist what prescription and nonprescription drugs, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • The following nonprescription or herbal product may interact with hydroxychloroquine: cimetidine (Tagamet HB). Be sure to let your doctor and pharmacist know that you are taking this medication before you start taking hydroxychloroquine. Do not start this medication while taking hydroxychloroquine without discussing it with your healthcare provider.
  • if you are taking antacids, take them 4 hours before or 4 hours after hydroxychloroquine.
  • tell your doctor if you or anyone in your family has or has ever had a prolonged QT interval (a rare heart problem that may cause irregular heartbeat, fainting, or sudden death) or if you are of Asian descent. Also, tell your doctor if you have or have ever had heart failure, a heart attack, an irregular heartbeat, or any other heart problems; a low level of magnesium or potassium in your blood; psoriasis; porphyria (an inherited blood disease that may cause skin or nervous system problems), glucose-6-phosphate dehydrogenase deficiency (G-6-PD; an inherited blood disease), or other blood disorders; dermatitis (skin inflammations); seizures; vision problems, including macular degeneration (an ongoing disease of the eye that causes loss of the ability to see straight ahead); diabetes; kidney or liver problems; or if you drink large amounts of alcohol.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking hydroxychloroquine, call your doctor.
  • you should know that hydroxychloroquine may cause serious and potentially irreversible eye problems. You will probably need to have regular eye exams during your treatment with hydroxychloroquine. Tell your doctor if you have any of the following: blurred vision, floaters in the eye, seeing flashes of light, or other changes in vision.
  • you should know that hydroxychloroquine can cause hypoglycemia (low blood sugar). Your doctor may tell you to monitor your blood sugar. Call your doctor or get emergency medical treatment if you have symptoms of hypoglycemia, including dizziness, weakness, tiredness, sweating, nausea, rapid or irregular heartbeat, confusion, fainting, or loss of consciousness.

What should I do if I forget a dose?

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What side effects can this medication cause?

Hydroxychloroquine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • headache
  • loss of appetite
  • nausea
  • diarrhea
  • stomach pain
  • vomiting
  • difficulty hearing
  • ringing in ears
  • hair loss
  • hair color changes

If you experience any of the following symptoms or those mentioned in the SPECIAL PRECAUTIONS section, call your doctor immediately:

  • hives; rash; swelling of the face, eyes, mouth, throat, tongue, lips, hands, feet, ankles, or lower legs; or difficulty breathing or swallowing
  • blisters on the skin, eyes, lips or in the mouth; or itching or burning skin
  • muscle weakness
  • burning, numbness, or tingling in the hands or feet
  • excessive tiredness, loss of appetite, nausea, yellowing of the skin or eyes, dark urine, pain in the upper right part of the stomach
  • unusual bleeding or bruising
  • cough, fever, sore throat, runny nose, or other signs of infection
  • mood or mental changes
  • fast or irregular heartbeat
  • lightheadedness, dizziness, or fainting
  • unusual tiredness or weakness
  • seizures
  • new or worsening depression
  • mood changes
  • thinking about harming or killing yourself

Hydroxychloroquine may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online ( or by phone (1-800-332-1088).

What should I know about storage and disposal of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach.

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website ( for more information if you do not have access to a take-back program.

In case of emergency/overdose

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

Symptoms of overdose may include:

  • fast or irregular heartbeat
  • lightheadedness, dizziness, or fainting
  • visual disturbances
  • loss of vision
  • seizures
  • decreased consciousness or coma

What other information should I know?

Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests and electrocardiograms (EKG, a test to monitor your heart rate and rhythm) to check your response to hydroxychloroquine.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

Brand names

  • Plaquenil®
Last Revised - 10/15/2023