Hydroxychloroquine (Plaquenil)

Reviewed by: HU Medical Review Board | Last reviewed: May 2023

Hydroxychloroquine (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 percent 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

These are not all the possible side effects of hydroxychloroquine. Talk to your doctor about what to expect when taking hydroxychloroquine. You also should call your doctor if you have any changes that concern you when taking hydroxychloroquine.

Other things to know

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.

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