Last updated on RxList: 5/18/2021
Plaquenil Side Effects Center

What Is Plaquenil?

Plaquenil (hydroxychloroquine) is an antimalarial medication used to treat or prevent malaria, a disease caused by parasites, which enter the body through the bite of a mosquito. Plaquenil is also used to treat symptoms of rheumatoid arthritis and discoid or systemic lupus erythematosus. Plaquenil is available in generic form.

What Are Side Effects of Plaquenil?

Common side effects of Plaquenil include

Tell your doctor if you experience serious side effects of Plaquenil including

  • muscle weakness,
  • twitching,
  • uncontrolled movement,
  • loss of balance or coordination,
  • blurred vision,
  • light sensitivity,
  • seeing halos around lights,
  • pale skin,
  • easy bruising or
  • bleeding,
  • confusion,
  • unusual thoughts or behavior, or
  • seizures (convulsions).

Dosage for Plaquenil

The adult dose of Plaquenil to suppress malaria is 400 mg on the same day each week. The pediatric weekly suppressive dosage is 5 mg/kg of body weight. The adult dose of Plaquenil to treat an acute attack of malaria is an initial dose of 800 mg followed by 400 mg in six to eight hours and 400 mg for two more days. To treat lupus erythematosus, the average adult dose is 400 mg once or twice daily.

What Drugs, Substances, or Supplements Interact with Plaquenil?

Plaquenil may interact with acetaminophen, cancer medications, tuberculosis medications, birth control pills or hormone replacement therapy, arthritis medications, ACE inhibitors, antibiotics, antifungals, cholesterol medications, HIV/AIDS medications, NSAIDs (non-steroidal anti-inflammatory drugs), or seizure medications. Tell your doctor all medications you use.

Plaquenil During Pregnancy and Breastfeeding

Plaquenil should be used only when prescribed during pregnancy. This medication is not recommended to treat rheumatoid arthritis during pregnancy. This medication passes into breast milk. Consult your doctor before breast-feeding.

Additional Information

Our Plaquenil (hydroxychloroquine) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Plaquenil Consumer Information

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Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Also seek emergency medical attention if you have symptoms of a serious heart problem: fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness (like you might pass out).

Call your doctor at once if you have:

  • a seizure;
  • yellowing of your eyes;
  • ringing in your ears, trouble hearing;
  • unusual mood changes;
  • severe muscle weakness, loss of coordination, underactive reflexes;
  • low blood cell counts--fever, chills, tiredness, sore throat, mouth sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath;
  • low blood sugar--headache, hunger, sweating, irritability, dizziness, fast heart rate, and feeling anxious or shaky; or
  • a serious drug reaction that can affect many parts of your body--skin rash, fever, swollen glands, muscle aches, severe weakness, unusual bruising, or yellowing of your skin or eyes.

Taking hydroxychloroquine long-term or at high doses may cause irreversible damage to the retina of your eye. Stop taking hydroxychloroquine and tell your doctor if you have:

  • blurred vision, trouble focusing, trouble reading;
  • distorted vision, blind spots;
  • changes in your color vision;
  • hazy or cloudy vision;
  • seeing light flashes or streaks, seeing halos around lights; or
  • increased sensitivity to light.

Common side effects may include:

  • headache, dizziness;
  • nausea, vomiting, stomach pain;
  • loss of appetite, weight loss;
  • feeling nervous or irritable;
  • skin rash or itching; or
  • hair loss.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Plaquenil (Hydroxychloroquine)


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The following adverse reactions are described in greater detail in other sections:

  • Cardiomyopathy and Ventricular Arrhythmias [see WARNINGS AND PRECAUTIONS]
  • Retinal Toxicity [see WARNINGS AND PRECAUTIONS]
  • Serious Skin Reactions [see WARNINGS AND PRECAUTIONS]
  • Worsening of Psoriasis and Porphyria [see WARNINGS AND PRECAUTIONS]
  • Hematologic Toxicity [see WARNINGS AND PRECAUTIONS]
  • Hemolytic Anemia Associated with G6PD [see WARNINGS AND PRECAUTIONS]
  • Skeletal Muscle Myopathy or Neuropathy [see WARNINGS AND PRECAUTIONS]
  • Neuropsychiatric Reactions Including Suicidality [see WARNINGS AND PRECAUTIONS]
  • Hypoglycemia [see WARNINGS AND PRECAUTIONS]

The following adverse reactions have been identified during post-approval use of 4aminoquinoline drugs, including PLAQUENIL. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure:

  • Blood and lymphatic system disorders: Bone marrow depression, anemia, aplastic anemia, agranulocytosis, leukopenia, thrombocytopenia
  • Cardiac disorders: Cardiomyopathy, cardiac failure, QT-interval prolongation, ventricular tachycardia, torsades de pointes, atrioventricular block, bundle branch block, sick sinus syndrome, pulmonary hypertension
  • Ear and labyrinth disorders: Vertigo, tinnitus, nystagmus, sensorineural hearing loss
  • Eye disorders: Retinopathy, retinal pigmentation changes (typically bull's eye appearance), visual field defects (paracentral scotomas), macular degeneration, corneal edema, corneal opacities, decreased dark adaptation
  • Gastrointestinal disorders: Nausea, vomiting, diarrhea, abdominal pain
  • General disorders: Fatigue -Hepatobiliary disorders: Abnormal liver function tests, fulminant hepatic failure
  • Immune system disorders: Urticaria, angioedema, bronchospasm
  • Metabolism and nutrition disorders: Anorexia, hypoglycemia, weight loss
  • Musculoskeletal and connective tissue disorders: Proximal myopathy, depressed tendon reflexes, abnormal nerve conduction
  • Nervous system disorders: Ataxia, dizziness, headache, seizure, extrapyramidal disorders (dystonia, dyskinesia, tremor)
  • Psychiatric disorders: Affect/emotional lability, irritability, nervousness, nightmares, psychosis, suicidal ideation, suicidal behavior
  • Skin and subcutaneous tissue disorders: Alopecia, hair color changes, rash, pruritus, photosensitivity, psoriasis exacerbation, hyperpigmentation, exfoliative dermatitis, erythema multiforme, acute generalized exanthematous pustulosis, Drug Rash with Eosinophilia and Systemic Symptoms (DRESS syndrome), Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN)


Drugs Prolonging QT Interval And Other Arrhythmogenic Drugs

PLAQUENIL prolongs the QT interval. There may be an increased risk of inducing ventricular arrhythmias if PLAQUENIL is used concomitantly with other arrhythmogenic drugs. Therefore, PLAQUENIL is not recommended in patients taking other drugs that have the potential to prolong the QT interval or are arrhythmogenic [see WARNINGS AND PRECAUTIONS].

Insulin Or Other Antidiabetic Drugs

PLAQUENIL may enhance the effects of insulin and antidiabetic drugs, and consequently increase the hypoglycemic risk. Therefore, a decrease in dosage of insulin and other antidiabetic drugs may be necessary [see WARNINGS AND PRECAUTIONS].

Drugs That Lower The Seizure Threshold

PLAQUENIL can lower the seizure threshold. Co-administration of PLAQUENIL with other antimalarials known to lower the seizure threshold (e.g., mefloquine) may increase the risk of seizures.


The activity of antiepileptic drugs might be impaired if co-administered with PLAQUENIL.


Concomitant use of PLAQUENIL and methotrexate may increase the incidence of adverse reactions.


An increased plasma cyclosporin level was reported when cyclosporin and PLAQUENIL were co-administered. Monitor serum cyclosporine levels closely in patients receiving combined therapy.


Concomitant PLAQUENIL and digoxin therapy may result in increased serum digoxin levels. Monitor serum digoxin levels closely in patients receiving combined therapy.


Concomitant use of cimetidine resulted in a 2-fold increase of exposure of chloroquine, which is structurally related to hydroxychloroquine. Interaction of cimetidine with hydroxychloroquine cannot be ruled out. Avoid concomitant use of cimetidine.


Lack of efficacy of hydroxychloroquine was reported when rifampicin was concomitantly administered. Avoid concomitant use of rifampicin.


Chloroquine has been reported to reduce the bioavailability of praziquantel. Interaction of praziquantel with hydroxychloroquine cannot be ruled out.

Antacids And Kaolin

Antacids and kaolin can reduce absorption of chloroquine; an interval of at least 4 hours between intake of these agents and chloroquine should be observed. Interaction of antacids and kaolin with hydroxychloroquine cannot be ruled out.


In a study of healthy volunteers, chloroquine significantly reduced the bioavailability of ampicillin. Interaction of ampicillin with hydroxychloroquine cannot be ruled out.

Read the entire FDA prescribing information for Plaquenil (Hydroxychloroquine)


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© Plaquenil Patient Information is supplied by Cerner Multum, Inc. and Plaquenil Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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