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Plaquenil Side Effects

Generic name: hydroxychloroquine

Medically reviewed by Last updated on Apr 28, 2022.

Note: This document contains side effect information about hydroxychloroquine. Some of the dosage forms listed on this page may not apply to the brand name Plaquenil.

For the Consumer

Applies to hydroxychloroquine: oral tablet

Side effects requiring immediate medical attention

Along with its needed effects, hydroxychloroquine (the active ingredient contained in Plaquenil) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking hydroxychloroquine:

Incidence not known

  • Anxiety
  • black, tarry stools
  • bleeding gums
  • blindness
  • blistering, peeling, loosening of the skin
  • blood in the urine or stools
  • blurred vision or other vision changes
  • change in how colors look
  • chest discomfort, pain, or tightness
  • chills
  • cold sweats
  • confusion
  • cough or hoarseness
  • dark urine
  • decreased urination
  • defective color vision
  • diarrhea
  • difficulty seeing at night
  • dilated neck veins
  • dizziness or fainting
  • fast, pounding, uneven heartbeat
  • feeling that others are watching you or controlling your behavior
  • feeling that others can hear your thoughts
  • feeling, seeing, or hearing things that are not there
  • fever
  • headache
  • inability to move the eyes
  • increased blinking or spasms of the eyelid
  • increased hunger
  • joint or muscle pain
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, and sex organs
  • loss of hearing
  • lower back or side pain
  • nervousness
  • nightmares
  • noisy breathing
  • painful or difficult urination
  • pale skin
  • palpitations
  • pinpoint red spots on the skin
  • red irritated eyes
  • red skin lesions, often with a purple center
  • seizures
  • severe mood or mental changes
  • shakiness
  • slurred speech
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • sticking out of the tongue
  • stomach pain
  • swelling of the eye
  • swelling of the face, fingers, feet, or lower legs
  • swollen or painful glands
  • trouble with breathing, speaking, or swallowing
  • uncontrolled twisting movements of the neck, trunk, arms, or legs
  • unusual behavior
  • unusual bleeding or bruising
  • unusual facial expressions
  • unusual tiredness or weakness
  • weight gain
  • yellow eyes or skin

Get emergency help immediately if any of the following symptoms of overdose occur while taking hydroxychloroquine:

Symptoms of overdose

  • Drowsiness
  • dry mouth
  • increased thirst
  • loss of appetite
  • mood changes
  • no pulse or blood pressure
  • numbness or tingling in the hands, feet, or lips
  • unconsciousness

Side effects not requiring immediate medical attention

Some side effects of hydroxychloroquine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Incidence not known

  • Continuing ringing or buzzing or other unexplained noise in the ears
  • darkening of the skin
  • feeling of constant movement of self or surroundings
  • hair loss or thinning of the hair
  • increased sensitivity of the skin to sunlight
  • irritability
  • loss of appetite
  • nausea
  • redness or other discoloration of the skin
  • sensation of spinning
  • severe sunburn
  • shakiness and unsteady walk
  • uncontrolled eye movements
  • unsteadiness, trembling, or other problems with muscle control or coordination
  • vomiting
  • weight loss

For Healthcare Professionals

Applies to hydroxychloroquine: compounding powder, oral tablet


QT interval prolongation has been reported in patients with specific risk factors, which may lead to arrhythmia (torsade de pointes, ventricular tachycardia).[Ref]

Rare (0.01% to 0.1%): Cardiomyopathy (sometimes resulting in cardiac failure; some with fatal outcome), conduction disorders (bundle branch block/atrioventricular heart block), biventricular hypertrophy

Frequency not reported: Arrhythmia (torsade de pointes, ventricular tachycardia)

Postmarketing reports: QT interval prolongation, ventricular arrhythmias, torsade de pointes[Ref]


Common (1% to 10%): Blurred vision (including due to disturbance of accommodation)

Uncommon (0.1% to 1%): Retinopathy (with changes in pigmentation, visual field defects), retinal changes (including paracentral, pericentral ring types, temporal scotomas, abnormal color vision), corneal changes (including edema, opacities), haloes, photophobia

Very rare (less than 0.01%): Extraocular muscle palsies

Frequency not reported: Maculopathies, macular degeneration, abnormal macular pigmentation and depigmentation (sometimes with bull's eye appearance), pallor of optic disc, optic atrophy, narrowing of retinal arterioles

Postmarketing reports: Irreversible retinopathy with retinal pigmentation changes (bull's eye appearance), visual field defects (paracentral scotomas), visual disturbances (visual acuity), maculopathies (macular degeneration), decreased dark adaptation, color vision abnormalities, corneal changes (edema, opacities), corneal deposition of drug with or without accompanying symptoms (halo around lights, photophobia, blurred vision[Ref]

Blurred vision (temporary) and extraocular muscle palsies (reversible) were due to disturbance of accommodation, which was dose dependent and reversible.

Retinopathy appeared to be uncommon when the recommended daily dose was not exceeded. In its early form, it appeared reversible when therapy was discontinued. If allowed to develop, there was risk of progression even after treatment withdrawal.

Patients with retinal changes were asymptomatic initially or had scotomatous vision with paracentral, pericentral ring types, temporal scotomas, and abnormal color vision.

Corneal changes (including edema and opacities) have occurred from 3 weeks (infrequently) to some years after starting therapy. They were either symptomless or caused disturbances such as haloes, blurred vision, or photophobia; they may be transient and were reversible when therapy was discontinued.

Maculopathies and macular degeneration have been reported (onset ranging from 3 months to several years of exposure to this drug) and may be irreversible.[Ref]


Very common (10% or more): Abdominal pain, nausea

Common (1% to 10%): Diarrhea, vomiting[Ref]

In general, abdominal pain, nausea, diarrhea, and vomiting resolved immediately when the dose was reduced or therapy was stopped.[Ref]


In general, skin rash, pruritus, pigmentation disorders in skin and mucous membranes, bleaching of hair, and alopecia resolved readily when therapy was discontinued.

AGEP had to be distinguished from psoriasis, although this drug has precipitated attacks of psoriasis. AGEP has been associated with fever and hyperleukocytosis. In general, outcome was favorable after stopping this drug.[Ref]

Common (1% to 10%): Skin rash, pruritus, alopecia

Uncommon (0.1% to 1%): Pigmentary changes, pigmentation disorders in skin and mucous membranes, bleaching of hair

Rare (0.01% to 0.1%): Attacks of psoriasis

Very rare (less than 0.01%): Dermatitis bullous eruptions, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, drug rash with eosinophilia and systemic symptoms (DRESS) syndrome, photosensitivity, exfoliative dermatitis, acute generalized exanthematous pustulosis (AGEP)

Frequency not reported: Urticaria, angioedema

Postmarketing reports: Hair color changes[Ref]


Common (1% to 10%): Anorexia

Rare (0.01% to 0.1%): Exacerbation/precipitation of porphyria

Postmarketing reports: Hypoglycemia, decreased appetite, porphyria[Ref]

Nervous system

Common (1% to 10%): Headache

Uncommon (0.1% to 1%): Dizziness, nerve deafness, vertigo, tinnitus

Rare (0.01% to 0.1%): Seizure/convulsions, neuromyopathy

Very rare (less than 0.01%): Nystagmus, ataxia

Frequency not reported: Hearing loss

Postmarketing reports: Extrapyramidal disorders (e.g., dystonia, dyskinesia, tremor), deafness[Ref]


Common (1% to 10%): Affect/emotional lability

Uncommon (0.1% to 1%): Nervousness

Very rare (less than 0.01%): Psychosis, suicidal behavior, nightmares

Postmarketing reports: Irritability[Ref]


Uncommon (0.1% to 1%): Abnormal liver function tests

Very rare (less than 0.01%): Fulminant hepatitis

Postmarketing reports: Acute/fulminant hepatic failure[Ref]


Uncommon (0.1% to 1%): Sensorimotor disorders

Frequency not reported: Absent/hypoactive deep tendon reflexes

Postmarketing reports: Skeletal muscle myopathy/muscle weakness/neuromyopathy (leading to progressive weakness, atrophy of proximal muscle groups), depression of tendon reflexes, abnormal nerve conduction studies[Ref]

Myopathy has been reversible after therapy discontinuation, but recovery has taken many months.[Ref]


Rare (0.01% to 0.1%): Bone-marrow failure/depression, anemia, aplastic anemia, leukopenia, thrombocytopenia

Very rare (less than 0.01%): Agranulocytosis

Postmarketing reports: Hemolysis (in glucose-6-phosphate dehydrogenase deficient patients)[Ref]


Very rare (less than 0.01%): Weight decreased/loss, fatigue/lassitude[Ref]


Postmarketing reports: Bronchospasm[Ref]


Frequency not reported: Allergic reactions (urticaria, angioedema, bronchospasm), hypersensitivity myocarditis[Ref]

Frequently asked questions


1. "Product Information. Plaquenil (hydroxychloroquine)." Apothecon Inc (2022):

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

3. Cerner Multum, Inc. "Australian Product Information." O 0

4. "Product Information. Hydroxychloroquine Sulfate (hydroxychloroquine)." Prasco Laboratories (2017):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.