Hydroxychloroquine is a prescription drug that’s been around since the 1940s. Doctors first used it to treat malaria.

Today you’re more likely to take it if you have rheumatoid arthritis or lupus. You may have heard it can treat COVID-19. 

The benefits for treating certain conditions outweigh the risks. You should only take it if your doctor says it’s OK or if you’re in a clinical trial. That’s because it can cause serious side effects. Here’s what you need to know.

Does It Treat COVID-19?

The evidence is mixed. There’s interest in hydroxychloroquine as a COVID-19 treatment because early studies in the lab showed promise. They found that the drug had some antiviral effect on the cells infected with SARS-CoV-2. That’s the virus that causes COVID-19. So far, there’s no strong evidence that it does the same thing in people. The studies have since been retracted, or pulled back.

The Food and Drug Administration (FDA) approved emergency use of hydroxychloroquine for a short time. They pulled approval after a large study found no evidence that the drug could stop deaths or help people with COVID-19 get better faster.More research is needed.

What Conditions Does It Treat?

It’s most often used to treat autoimmune disorders. That’s when your body’s immune system attacks your cells and tissue by mistake. It can lead to inflammation that damages your joints, muscles, and sometimes your internal organs.

Your doctor might give you hydroxychloroquine if you have:

Experts aren’t sure how hydroxychloroquine helps. They think it’s because the drug changes how your immune cells send signals. It can also turn off certain processes that cause inflammation.

Side Effects

You might not have any problems if you take hydroxychloroquine. But like any drug, it could cause unwanted symptoms. Some are mild and might get better with time.

The most common side effects are:

You could get low blood sugar if your diabetes isn’t under control. It might help if you take hydroxychloroquine with food.

Other symptoms you can get include:

  • Itching or rash
  • Darkening skin or dark spots
  • Hair changes
  • Muscle weakness
  • Mood problems
  • Ringing in your ears


Serious Side Effects

Hydroxychloroquine could cause fatal heart rhythm problems, especially if you take it with another drug. That includes the antibiotic azithromycin. The most common issue is a prolonged QT interval. That’s when your heart’s lower chambers, or ventricles, don’t send electrical signals the right way. It can also make your heart beat too fast. That’s ventricular tachycardia.

It’s rare, but hydroxychloroquine can also damage your eyes. You could have permanent changes in your vision or blindness. You’re more likely to have these kinds of problems if:

  • You’re 60 or older
  • You’ve taken a high dose for more than 5 years
  • You have serious kidney or liver disease
  • You already have an eye or retinal disease

Get regular eye exams if you take this drug long term. Your doctor may want you to get your vision checked every 1-5 years.

Other serious side effects can include:

  • Blood and lymph system disorders
  • Kidney problems
  • Liver injury or failure

Rarely, hydroxychloroquine can cause anemia. That may happen if you have glucose-6-phosphate dehydrogenase (G6PD) deficiency or porphyria. Those are disorders that affect how your red blood cells work.


Hydroxychloroquine doesn’t mix well with certain drugs. It can change the way those medicines work. It can also raise your chances of unwanted side effects. Tell your doctor about any medicine or supplements you’re taking, including vitamins.

Don’t take hydroxychloroquine with:

  • Cisapride
  • Dronedarone
  • Pimozide
  • Thioridazine

Drugs it can interact with include:

There’s also a chance it could interact with these drugs:

Talk to your doctor if you take tamoxifen for breast cancer. It might not be safe to take it with hydroxychloroquine for more than 6 months.

Who Can Take It?

It’s safe for most adults and kids to take hydroxychloroquine. Your doctor will use your weight to get the right dose.

Studies show it’s OK to take hydroxychloroquine if you’re pregnant or breastfeeding. Always talk to your doctor about what drugs you’re taking.

Be careful if you have psoriasis. It might make your symptoms worse.


Who Can’t Take it?

Don’t take hydroxychloroquine if you’re allergic to other drugs with 4-aminoquinoline compounds. That includes medicine such as:

Call 911 or get help right away if you have signs of an allergic reaction. You might get symptoms like:

  • Swelling in your throat, mouth, or face
  • Skin rash or bumps
  • Itching
WebMD Medical Reference Reviewed by Neha Pathak, MD on August 10, 2021



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DailyMed (NIH): “Hydroxychloroquine Sulfate tablet.”

Arthritis Foundation: “DMARDS.”

CDC: “Medicines for the Prevention of Malaria While Traveling – Hydroxychloroquine (Plaquenil).”

Nature Reviews Rheumatology: “Mechanisms of action of hydroxychloroquine and chloroquine: implications for rheumatology.”

Infectious Diseases Society of America: “Infectious Diseases Society of America Guidelines on the Treatment and Management of Patients with COVID-19.”

American College of Rheumatology: “Hydroxychloroquine (Plaquenil).”

FDA: “FDA cautions against use of hydroxychloroquine or chloroquine for COVID-19 outside of the hospital setting or a clinical trial due to risk of heart rhythm problems.”

Cleveland Clinic: “Why You Shouldn’t Take Hydroxychloroquine for Coronavirus,” “Hydroxychloroquine tablets.” 

International Journal of Infectious Diseases: “Treatment with hydroxychloroquine, azithromycin, and combination in patients hospitalized with COVID-19.”

FDA: “Pharmacovigilance Memorandum: Hydroxychloroquine and Chloroquine.”

Mayo Clinic: “Prolonged QT interval.”

Cleveland Clinic Journal of Medicine: “Hydroxychloroquine use in the COVID-19 patient.”

Pediatric Rheumatology: “Systematic review of hydroxychloroquine use in pregnant patients with autoimmune diseases.”

National Psoriasis Foundation: “Psoriasis Causes and Triggers.”

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