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Hydroxychloroquine and a related drug, chloroquine, are currently under study as possible treatments for COVID-19, the illness caused by the SARS-CoV-2 coronavirus. These drugs have not yet been approved by the Food and Drug Administration (FDA) for this use. Do not use these medications to treat COVID-19 unless your doctor recommends that you do so.

Hydroxychloroquine is available in the United States by prescription only. Avoid websites claiming to sell prescription medications to American consumers without a prescription. That’s illegal and a sign the pharmacy is illegitimate. Also avoid any pharmacy not based in the U.S up to 50% of the medicines sold online may be fake.

Hydroxychloroquine (also known by the brand name Plaquenil) is a medication used to prevent malaria and to treat discoid or systemic lupus erythematosus and rheumatoid arthritis in patients whose symptoms have not improved with other treatments. 

Side Effects

Hydroxychloroquine may cause side effects. Tell your doctor if any of these symptoms are severe or persist:

  • headache;
  • dizziness;
  • loss of appetite;
  • nausea;
  • diarrhea;
  • stomach pain;
  • vomiting; or
  • skin rash.

If you experience any of the following symptoms, call your doctor immediately:

  • reading or seeing difficulties (words, letters, or parts of objects missing);
  • sensitivity to light;
  • blurred distance vision;
  • seeing light flashes or streaks;
  • difficulty hearing;
  • ringing in ears;
  • muscle weakness;
  • bleeding or bruising of the skin;
  • bleaching or loss of hair;
  • mood or mental changes;
  • irregular heartbeat;
  • drowsiness; or
  • convulsions.

If you miss a dose, take the missed dose as soon as you can. However, if it’s almost time for the next scheduled dose, skip the missed dose and continue your regular dosing schedule. Don’t take a double dose to make up for the missed one as you would risk more serious side effects.

In high doses, hydroxychloroquine can cause damage to the eyes, leading to vision problems that can be permanent. Hydroxychloroquine can also damage the heart, causing heart disease. While uncommon, some cases have been fatal.

Drug Interactions

Hydroxychloroquine can interact with other medications or supplements you may be taking. This can be harmful or prevent the medications from working well. To help avoid interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all prescriptions and over-the-counter medications or supplements you’re taking. To find out how this drug might interact with something else you’re taking, talk to your doctor or pharmacist. 

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Taking hydroxychloroquine with certain other malaria drugs such as mefloquine can increase your risk of seizures.

Taking antiseizure drugs phenytoin or carbamazepine with hydroxychloroquine can make the antiseizure drugs less effective.

Taking immunosuppressant cyclosporine with hydroxychloroquine can increase the amount of cyclosporine in your body, increasing the risk of side effects.

Taking the heart drug digoxin with hydroxychloroquine may increase the levels of digoxin in your body, increasing the risk of side effects.

Hydroxychloroquine should not be taken with other drugs that affect heart rhythm. Taking hydroxychloroquine with these drugs could cause dangerous arrhythmias. Examples of these drugs include:

  • amiodarone
  • chlorpromazine
  • clarithromycin

Hydroxychloroquine and diabetes drugs all decrease your blood sugar level. Taking hydroxychloroquine with these drugs could cause hypoglycemia (low blood sugar). Your doctor may need to reduce your dosage of insulin or the other diabetes drugs, such as:

  • chlorpropamide
  • glipizide
  • glimepiride
  • glyburide
  • repaglinide

Complication Warnings

Hydroxychloroquine may worsen skin conditions psoriasis and porphyria as well as negatively affect people with certain blood enzyme deficiencies. Liver problems may make hydroxychloroquine less effective.

Hydroxychloroquine can be dangerous to children. Accidentally swallowing even just a few tablets can lead to death in a small child. Older children shouldn’t use this drug for long periods as they may experience permanent damage to their vision and other side effects. Pregnant women and women who are breastfeeding should avoid hydroxychloroquine as they can pass the drug through their bloodstream or breastmilk.

Clinical Monitoring

Your doctor will examine you periodically to check your health and make sure that you aren’t having side effects from your medication. Eye exams, reflex tests, blood tests, and heart tests should be routinely administered to check for hydroxychloroquine’s more harmful side-effects or interactions.


First DataBank

American Society of Health-System Pharmacists (ASHP)

National Association of Boards of Pharmacy (NABP)



Alliance for Safe Online Pharmacies (ASOP)