Hydroxychloroquine (Plaquenil)

Reviewed by: HU Medical Review Board | Last reviewed: March 2022 | Last updated: April 2022

Hydroxychloroquine (brand name:Plaquenil) is a disease-modifying anti-rheumatic drug (DMARD) approved for adults with RA. It is often given in combination with methotrexate and sulfasalazine (a treatment known as triple therapy), to help slow RA disease progression for patients who do not get relief from methotrexate therapy alone.1,2

Research shows that this medication reduces RA symptoms, including pain, swelling, and tenderness, and improves physical functioning in up to 80% of patients. Hydroxychloroquine can also decrease the frequency of RA flares.3

Plaquenil is also available in generic forms.

What are the ingredients in hydroxychloroquine?

The active ingredient in hydroxychloroquine is hydroxychloroquine sulfate.4

How does hydroxychloroquine work?

Hydroxychloroquine is an antimalarial drug. It is derived from quinine and cinchonine, which were originally taken from the bark of the cinchona tree found in Peru. Antimalarials modulate or change the way the immune system works. The exact mechanism of action for hydroxychloroquine and another antimalarial drug chloroquine in RA is not known, but researchers think these drugs decrease production of a number of different chemicals that are important to the immune response.3

What are the possible side effects of hydroxychloroquine?

Common side effects associated with hydroxychloroquine include5:

  • headache
  • dizziness
  • loss of appetite
  • nausea
  • diarrhea
  • stomach pain
  • vomiting
  • skin rash
  • hypoglycemia (low blood sugar)

If you experience any of the following symptoms while taking hydroxychloroquine, call your doctor immediately5:

  • problems seeing or reading (including if words, letters, or parts of objects are missing)
  • light sensitivity
  • 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, including suicidal thoughts
  • irregular heartbeat
  • drowsiness
  • convulsions
  • sun sensitivity

This is not an exhaustive list of all potential side effects of hydroxychloroquine. For more information, consult your doctor or healthcare provider. If you notice any new or worsening side effects, contact your doctor or healthcare provider immediately. For more information on adverse effects, see the FDA black box warning for hydroxychloroquine.

Things to note about hydroxychloroquine

Before taking hydroxychloroquine, tell your doctor if you:

  • Are allergic to the medication
  • Have any cardiac issues
  • Have diabetes
  • Have eye problems or vision changes, especially retinopathy
  • Are pregnant or plan to become pregnant
  • Are breastfeeding
  • Have or have ever had liver disease, psoriasis, skin inflammation, or blood problems
  • Drink large amounts of alcohol5

Serious, irreversible eye damage has occurred, though rarely, for patients taking hydroxychloroquine. Risk factors include long-term high-dose use of the medication, pre-existing severe kidney disease, age over 60. If you are taking hydroxychloroquine over a long duration, it is important to take eye exams every 6 to 12 months.6 Do not take hydroxychloroquine if you experience vision symptoms, including problems seeing or reading, light sensitivity, blurred distance vision, or light flashes or streaks.5

Certain drugs do not mix well with hydroxychloroquine, so you should tell your doctor about any other medications or supplements you are taking, including vitamins and supplements.

Drugs that do not mix well include digoxin (Lanoxin), iron-containing medications (including multivitamins), isoniazid (Nydrazid), methotrexate (Rheumatrex), niacin, and rifampin (Rifadin, Rimactane).v This is not a complete list of drugs that interact with hydroxychloroquine.

Editorial Note: On April 24, 2020, the FDA announced that there have been reports of serious heart rhythm problems in patients with COVID-19 treated with hydroxychloroquine or chloroquine. Because of these reports, the FDA cautioned against the use of hydroxychloroquine or chloroquine for COVID-19 outside of a hospital or a clinical trial. Close supervision by a medical team is strongly recommended. Hydroxychloroquine and chloroquine can cause abnormal heart rhythms. If you are receiving hydroxychloroquine or chloroquine for COVID-19 and have an irregular heartbeat, dizziness, or fainting, call 911 right away.

Editorial Note: On March 19, 2020, the FDA approved the testing of two drugs, hydroxychloroquine and remdesivir, to treat people with COVID-19. Hydroxychloroquine are also used to treat malaria, lupus, and rheumatoid arthritis. Both have been used for decades and are generally inexpensive and safe to use as prescribed. Remdesivir is an experimental antiviral drug that has not yet been approved for use in the U.S. or any other country. However, it has been tested in animals to fight MERS and SARS, two other serious infections in the coronavirus family. It is in the very early stages of being tested in humans to fight the Ebola virus.

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