Hydroxychloroquine - Uses, Side Effects, and More

What are the most common side effects of hydroxychloroquine?

The most common side effects of hydroxychloroquine are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

• Nausea and vomiting
• Diarrhea
• Stomach pain

There may be other side effects of hydroxychloroquine that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of hydroxychloroquine?

While less common, the most serious side effects of hydroxychloroquine are described below, along with what to do if they happen.

Heart Problems. Hydroxychloroquine may cause certain heart problems, such as cardiomyopathy, pulmonary hypertension, and sick sinus syndrome. These can sometimes lead to death. Call your healthcare provider right away if you have any of the following symptoms.

• Dizziness or feeling lightheaded
• Changes in your heart rate or rhythm, such as a fast or skipping heartbeat
• Fainting

Heart Rhythm Changes. Hydroxychloroquine may cause ventricular arrhythmias or a rare dangerous heart rhythm problem called QT prolongation and torsade de pointes. Some people have a higher risk for this, including people who are older, have other people in their family who have had these conditions, have low potassium or magnesium levels, or who take some medicines for other heart rhythm problems. Tell your healthcare provider right away if you faint or have changes in your heart rate or rhythm, such as a fast or skipping heartbeat.

Eye Problems. Hydroxychloroquine may cause damage to part of your eye, called the retina. This can lead to permanent vision problems. The risk is increased in people taking hydroxychloroquine for a long time or at high doses. Your healthcare provider may recommend an eye examination before or while you take hydroxychloroquine. Stop taking hydroxychloroquine and call your healthcare provider if you have any vision changes or notice any of the following symptoms.

• Trouble seeing (especially in the dark)
• Trouble adjusting to changes in brightness (especially going from light to dark)

Severe Skin Reactions. Hydroxychloroquine can cause severe skin reactions called Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) that can lead to death if not treated. If you develop a rash, stop taking hydroxychloroquine and call your healthcare provider right away. Get emergency help right away if you have any of the following symptoms of SJS or TEN.

• Painful red or purple skin that looks burned and peels off
• Flat red rash or blisters on your skin, mouth, nose, and genitals
• Red, painful, watery eyes

Severe Allergic Reactions. Hydroxychloroquine may cause allergic reactions, including a specific type of allergic reaction called DRESS. DRESS stands for Drug Reaction with Eosinophilia and Systemic Symptoms. It is also sometimes called multi-organ hypersensitivity. This is a reaction that can affect multiple parts of the body including your liver, kidneys, and heart. Stop taking the medicine and get help right away if you have any of the following symptoms of a serious allergic reaction.

• Breathing problems or wheezing
• Racing heart
• Itching, skin rash, or pale red bumps on the skin called hives
• Fever or general ill feeling
• Swollen lymph nodes
• Swelling of the face, lips, mouth, tongue, or throat
• Shortness of breath, trouble swallowing, or throat tightness
• Swelling in your feet, ankles, or legs
• Nausea or vomiting
• Dizziness, feeling lightheaded, or fainting
• Stomach cramps
• Joint pain
• Dark-colored pee
• Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking hydroxychloroquine. Call your healthcare provider right away if you have any of the following symptoms of liver damage.

• Nausea or vomiting
• Stomach or belly pain
• Fever
• Weakness or unusual tiredness
• Itching
• Loss of appetite
• Light-colored poop
• Dark-colored urine
• Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Kidney Damage. Kidney damage can happen when taking hydroxychloroquine. Stop taking hydroxychloroquine and call your healthcare provider right away if you have any of the following symptoms of kidney damage.

• Reduced need to pee
• Swelling in your feet, ankles, or legs
• Weakness or unusual tiredness
• Difficulty catching your breath or chest pain/pressure
• Confusion
• Nausea
• Seizures

Blood Disorders. Hydroxychloroquine can cause blood disorders, such as agranulocytosis, aplastic anemia, hemolytic anemia, low platelet levels (thrombocytopenia), and low white blood cell levels (leukopenia). Stop taking hydroxychloroquine and get help right away if you have any of the following symptoms of blood disorders.

• Fever
• Shortness of breath
• Pale or yellowish skin
• Easy bruising or bleeding
• Frequent infection
• Unusual weakness or tiredness
• Dizziness, lightheadedness, or feeling like you are about to pass out
• Headache
• Fast or abnormal heartbeat

Muscle or Nerve Problems. Hydroxychloroquine can cause muscle problems, including muscle pain, weakness, and tenderness called myopathy, or nerve problems called neuropathy. Neuropathy is commonly described as pain, burning, tingling, or numbness. Your healthcare provider may do tests to check for these while you are taking hydroxychloroquine. Stop taking hydroxychloroquine and tell your healthcare provider if you have unexplained muscle weakness.

Suicidal Thoughts and Actions. Hydroxychloroquine may cause suicidal thoughts or actions in a small number of people. This most often happens within the first month of taking the medicine. If you are about to harm yourself, call 911 or call or text 988, the Suicide & Crisis Lifeline. Call your healthcare provider right away if you have any of the following symptoms.

• New or increased thoughts of suicide or death
• Suicide attempt
• New or increased feelings of anxiety, depression, or other unusual changes in mood or behavior

Low Blood Sugar (Hypoglycemia). Hydroxychloroquine can cause low blood sugar, which can be serious and may lead to death. You may need to check your blood sugar more often if you have changes to your diet, exercise regimen, or medicines for diabetes. Do not take hydroxychloroquine and call your healthcare provider right away if you have any of the following symptoms of hypoglycemia.

• Headache
• Crankiness or anxiety 
• Hunger
• Dizziness or confusion
• Blurry vision
• Slurred speech
• Sweating
• Feeling jittery or shakiness
• Fast heartbeat
• Seizures