NOT USED FOR COVID-19

Hydroxychloroquine and a related drug, chloroquine, are not recommended for use in treating COVID-19 (the illness caused by the new coronavirus). Do not take any prescription drug, including hydroxychloroquine or chloroquine, unless your doctor recommends that you do so.

For information on how to prepare, advice on prevention and treatment, and expert recommendations, visit our COVID-19 hub.

Hydroxychloroquine (Plaquenil) is a generic prescription medication approved to:

Hydroxychloroquine comes as an oral tablet that you swallow. It isn’t available in other forms, such as an injectable or topical form. It’s also referred to as hydroxychloroquine sulfate. As with other drugs, hydroxychloroquine can cause side effects.

If you take hydroxychloroquine to treat or help prevent malaria, you’ll likely take it short term. However, if you take the drug for an autoimmune condition, such as rheumatoid arthritis or lupus, you’ll likely take it long term.

Read on to learn about potential common, mild, and serious side effects. For a general overview of hydroxychloroquine, including details about its uses, refer to this article. Your doctor can also tell you more about hydroxychloroquine.

Hydroxychloroquine can cause certain side effects (also called adverse effects), some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took hydroxychloroquine in clinical trials:

Mild side effects can occur with hydroxychloroquine use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to hydroxychloroquine’s prescribing information.

Mild side effects that have been reported with hydroxychloroquine include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while taking hydroxychloroquine and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Hydroxychloroquine: Side effect specifics” below.

Hydroxychloroquine may cause serious side effects. However, serious side effects are less common than mild side effects.

The list below may not include all possible serious side effects of the drug. For more information, you can refer to hydroxychloroquine’s prescribing information.

If you develop serious side effects while taking hydroxychloroquine, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported and their symptoms include:

  • Kidney problems. Symptoms can include:
    • urinating more or less than is typical
    • muscle cramps
    • nausea or vomiting
  • Decreased blood cell levels, including low red blood cells (anemia), low white blood cells (leukopenia) or low platelets (thrombocytopenia). Symptoms can include:
    • fatigue
    • dizziness
    • bruising or bleeding more than is typical
  • Muscle or nerve pain. Symptoms can include:
    • tingling of the hands or feet
    • shooting pain
    • sharp pain
  • Mood problems, including suicidal thoughts or behaviors. Symptoms can include:
    • unusual changes in mood
  • Low blood sugar. Symptoms can include:
    • sweating
    • dizziness
    • nervousness
  • Ear problems, such as hearing loss. Symptoms can include:
    • ringing of the ear
    • trouble hearing
  • Heart problems.*
  • Skin problems.*
  • Liver problems.*
  • Eye side effects.†
  • Severe allergic reaction.‡

* For more information about this side effect, see the “Hydroxychloroquine: Side effect specifics” section below.
† For more information, see the “Hydroxychloroquine: Eye side effects” section below.
‡ An allergic reaction is possible after taking Hydroxychloroquine. However, it’s not clear whether this side effect occurred in clinical trials. To learn more, see the “Hydroxychloroquine: Side effect specifics” section below.

You may be at an increased risk of side effects when taking the 300-milligram (mg) tablets compared with the 200-mg tablets. This is because when you take a higher strength of medication, your body is exposed to more of the drug. And having more of the drug in your body can increase your risk of side effects.

If you’re concerned about side effects that you may experience from taking hydroxychloroquine, talk with your doctor or pharmacist.

Although rare, it’s possible for hydroxychloroquine to cause eye side effects. You may also hear of these side effects referred to as ocular side effects.

Eye side effects from hydroxychloroquine may include:

  • retinopathy (damage to your retina, which is the layer of tissue at the back of the eyeball)
  • loss of vision
  • difficulty seeing in the dark

You may be at an increased risk of eye side effects if you take a higher dose of medication, if you take it for longer than 5 years, or if you have kidney problems or eye problems.

You are also at increased risk of eye side effects if you are taking hydroxychloroquine in combination with certain other medications. In this case, your doctor can recommend whether hydroxychloroquine may be a safe treatment option for you.

Due to these possible risks, your doctor will recommend getting an eye test done within your first year of taking hydroxychloroquine. Then, your doctor will recommend having eye tests done every so often while you’re taking hydroxychloroquine, to be sure that your eyes aren’t being affected.

If you do develop changes in vision or other eye side effects, tell your doctor right away. They may recommend stopping treatment with hydroxychloroquine. They may also recommend having regular eye exams after stopping the drug.

While catching eye problems early can help prevent permanent vision loss, eye problems may continue to worsen after stopping treatment in some people.

Learn more about some of the side effects that hydroxychloroquine may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for hydroxychloroquine.

Heart problems

It’s possible for hydroxychloroquine to cause heart problems. Although this side effect is not common in clinical trials, it may occur. Examples of these heart problems may include heart failure, changes in heart rhythm, or cardiomyopathy (weakening of the heart muscle).

If you already have a heart condition, you may be at an increased risk of heart problems when taking hydroxychloroquine.

Symptoms of heart problems may include:

What you can do

If you notice symptoms of heart problems, tell your doctor, or go to the hospital right away. They can help determine whether hydroxychloroquine may be contributing to your heart condition and how to treat it.

Skin problems

It’s possible for hydroxychloroquine to cause serious skin reactions. Skin reactions weren’t reported in clinical trials of the drug. However, severe skin reactions were reported in people taking hydroxychloroquine after it was approved for use. In rare cases, these skin reactions can be life threatening.

If you develop symptoms of a serious skin condition, tell your doctor right away. Symptoms may include:

  • blisters on your skin, eyes, or mouth
  • itching
  • fever
  • peeling of the skin

What you can do

If you develop skin problems during your treatment with hydroxychloroquine, tell your doctor. They can help determine whether hydroxychloroquine may be causing your skin reaction and can help treat it. In some cases, if you have a serious skin reaction, your doctor may recommend stopping hydroxychloroquine.

Liver problems

It’s possible for hydroxychloroquine to cause liver problems. Liver problems weren’t reported in clinical trials of the drug. However, liver problems were reported in people taking hydroxychloroquine after the drug was approved for use.

Liver problems that were reported include results showing elevated liver function in lab tests and liver failure. Symptoms of these conditions may include nausea, diarrhea, abdominal pain, or jaundice.

What you can do

If you develop symptoms of liver problems, tell your doctor right away. They can do blood tests to determine whether your liver is functioning as it should.

If you do develop a liver problem from taking hydroxychloroquine, your doctor may recommend stopping treatment with hydroxychloroquine. In this case, they will recommend a different treatment for your condition.

Weight loss

It’s possible for hydroxychloroquine to cause weight loss. However, weight loss wasn’t reported in clinical trials of people taking the drug. However, weight loss was reported in people taking hydroxychloroquine after the drug was approved.

What you can do

If you notice weight loss during your treatment with hydroxychloroquine, talk with your doctor. They can help determine whether your weight loss may be due to your treatment with hydroxychloroquine.

Diarrhea

It’s possible to develop diarrhea while taking hydroxychloroquine. Diarrhea was a common side effect in clinical trials of hydroxychloroquine.

What you can do

If you develop diarrhea while you’re taking hydroxychloroquine, talk with your doctor. They may be able to recommend ways to treat your diarrhea.

Allergic reaction

As with most drugs, hydroxychloroquine can cause an allergic reaction in some people. However, it’s not clear whether this side effect occurred in clinical trials.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking hydroxychloroquine.

However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Suicide prevention

If you know someone at immediate risk of self-harm, suicide, or hurting another person:

  • Ask the tough question: “Are you considering suicide?”
  • Listen to the person without judgment.
  • Call 911 or the local emergency number, or text TALK to 741741 to communicate with a trained crisis counselor.
  • Stay with the person until professional help arrives.
  • Try to remove any weapons, medications, or other potentially harmful objects.

If you or someone you know is having thoughts of suicide, a prevention hotline can help. The 988 Suicide and Crisis Lifeline is available 24 hours a day at 988. During a crisis, people who are hard of hearing can use their preferred relay service or dial 711 then 988.

Click here for more links and local resources.

Hydroxychloroquine may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Does hydroxychloroquine cause weight gain?

No, you shouldn’t experience weight gain from taking hydroxychloroquine. In fact, weight loss was reported in people taking hydroxychloroquine after the drug was approved.

If you notice weight gain during your treatment with hydroxychloroquine, talk with your doctor. They can help determine what may be causing your weight gain to occur.

What are the rare side effects of hydroxychloroquine?

It’s possible for hydroxychloroquine to cause rare side effects. However, most side effects that people taking hydroxychloroquine experience are mild.

Examples of rare side effects that may occur include heart problems, serious skin reactions, or liver problems. (For more information about these side effects, see the “Hydroxychloroquine: Side effect specifics” section above.)

If you have concerns about developing rare side effects from taking hydroxychloroquine, talk with your doctor or pharmacist.

Are there any long-term side effects of hydroxychloroquine?

Yes, it’s possible to develop long-term side effects from taking hydroxychloroquine. Though mild side effects are more common from hydroxychloroquine, it’s possible to develop long-term side effects from this medication. Examples of long-term side effects that may occur from this drug include:

  • mood problems
  • muscle or nerve pain
  • kidney problems
  • liver problems*
  • heart problems*
  • eye-related side effects, such as retinopathy†

If you are concerned about developing long-term side effects from hydroxychloroquine, talk with your doctor. They can discuss possible side effects with you.

* For more information about this side effect, see the “Hydroxychloroquine: Side effect specifics” section above.
† For more information, see the “Hydroxychloroquine: Eye side effects” section above.

Be sure to talk with your doctor about your health history before you take hydroxychloroquine. This drug may not be the right treatment option for you if you have certain medical conditions or other factors that affect your health. These are known as drug-condition or drug-factor interactions. The conditions and factors to consider include:

Heart problems. Tell your doctor about any heart problems that you have before starting hydroxychloroquine. This medication may increase your risk of heart problems, such as heart rhythm problems. And if you already have a heart condition, hydroxychloroquine may make your condition worse. Your doctor can help determine whether hydroxychloroquine may be safe for you to take.

Eye problems. Tell your doctor about any eye problems that you have. This medication can increase your risk of eye problems occurring. If you already have an eye condition, hydroxychloroquine may make your condition worse. In this case, your doctor can determine whether hydroxychloroquine may be safe for you.

Kidney problems. If you have any kidney problems, tell your doctor before taking hydroxychloroquine. It’s possible for this medication to cause kidney problems to occur. And if you already have kidney problems, taking hydroxychloroquine can make your condition worse. You can talk with your doctor to determine whether it’s safe for you to take hydroxychloroquine.

Low electrolyte levels. Your doctor may do blood tests before you start taking hydroxychloroquine. If you have any electrolyte problems, such as low magnesium or potassium, your doctor may recommend managing this before starting hydroxychloroquine. This is because if you have low electrolyte levels, you may be at an increased risk of heart problems from taking hydroxychloroquine.

Allergic reaction. If you’ve had an allergic reaction to hydroxychloroquine or any of its ingredients, your doctor will likely not prescribe hydroxychloroquine. Taking hydroxychloroquine could cause you to have another allergic reaction. Ask your doctor what other medications may be better options for you.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency. You may be at an increased risk of red blood cell problems if you have a G6PD deficiency and you take hydroxychloroquine. If you have G6PD deficiency, your doctor can help determine whether hydroxychloroquine may be safe for you.

Liver problems. Tell your doctor about any liver problems you have before starting hydroxychloroquine. Your doctor may recommend that you take a lower dose of hydroxychloroquine if you have liver problems.

Blood cell problems. It’s possible for hydroxychloroquine to cause low blood cell levels, including low platelets or low red blood cell levels (anemia). If you already have problems with your blood cell levels, taking hydroxychloroquine may make your condition worse. In this case, your doctor can help determine whether hydroxychloroquine is a safe treatment option for you.

Mental health conditions. It’s possible for hydroxychloroquine to increase your risk of mood problems such as depression, mood changes, or suicidal thoughts or behaviors. If you have a mental health condition, taking hydroxychloroquine may make your condition worse. In this case, your doctor may recommend monitoring you more often for changes in your mood.

Skin conditions. If you have a skin condition, tell your doctor before taking hydroxychloroquine. This medication can make certain skin conditions, such as psoriasis even worse. In this case, your doctor may recommend a different treatment option for you.

Alcohol with hydroxychloroquine

There aren’t any known interactions between hydroxychloroquine and alcohol.

However, it’s possible that drinking alcohol while taking hydroxychloroquine may increase your risk of side effects. For example, alcohol and hydroxychloroquine can cause nausea, vomiting, or liver problems.

If you consume alcohol, talk with your doctor to find out whether it’s safe to do so while taking hydroxychloroquine. They can also tell you how much, if any, is safe.

Pregnancy and breastfeeding while taking hydroxychloroquine

It’s not known whether hydroxychloroquine may be safe to take during pregnancy or while breastfeeding.

Clinical trials did not seem to indicate an increased risk of pregnancy loss or congenital anomalies (birth defects) when hydroxychloroquine was taken during pregnancy. In addition, there are risks to the birthing parent and the developing fetus if malaria, rheumatoid arthritis, or lupus is left untreated during pregnancy.

If you take hydroxychloroquine during pregnancy, you may wish to sign up for the pregnancy registry. Pregnancy registries are collections of data that help determine whether a drug is safe to take during pregnancy or what risks the drug may cause. To sign up for the pregnancy registry, call 877-311-8972.

Hydroxychloroquine is known to pass into breast milk, so a child who is breastfed will be exposed to the drug. However, no side effects have been reported in infants exposed to the drug through breastfeeding. It’s important to note that more information may be needed to determine whether hydroxychloroquine is safe to take while breastfeeding.

If you’re pregnant, planning to become pregnant, or breastfeeding, talk with your doctor before taking hydroxychloroquine.

If you’d like to learn more about hydroxychloroquine, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug. You can also ask them about Plaquenil, the brand-name version of hydroxychloroquine.

A generic drug and its brand-name version contain the same active ingredient, so they’re expected to have the same side effects. Referring to the following articles about hydroxychloroquine and Plaquenil can provide you with additional information:

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.