Side Effects of Plaquenil (hydroxychloroquine)

Hydroxychloroquine (Plaquenil) is an anti-malarial drug used to treat malaria, lupus erythematosus, and rheumatoid arthritis. Its mechanism of action is unknown.

Malarial parasites invade red blood cells. Hydroxychloroquine may prevent parasites from breaking down hemoglobin in red blood cells. Hydroxychloroquine is effective against Plasmodium vivax, P. malariae, P. ovale, and susceptible strains of P. falciparum.

Hydroxychloroquine also prevents inflammation caused by lupus erythematosus and rheumatoid arthritis. Hydroxychloroquine and chloroquine (Aralen) are being investigated for COVID-19 treatment but their effectiveness is unproven.

Common side effects of hydroxychloroquine include: irritability, headache, weakness, hair lightening or loss, stomach upset, nausea, dizziness, muscle pain, rash, and itching.

Serious side effects of hydroxychloroquine include: worsening of psoriasis, reduced white blood cells or platelets, abnormal red blood cells, severe eye toxicity leading to color blindness and vision loss, and severe anemia in patients deficient in a certain enzyme.

Hydroxychloroquine interacts with penicillamine and telbivudine, and suppresses the immune system. It should not be combined with other immune-suppressing drugs or live vaccines.

Hydroxychloroquine is safe for use in pregnant women for malaria prevention or treatment. It may be secreted in breast milk and cause side effects in infants.

Important Side Effects of Plaquenil (hydroxychloroquine)

WARNING

PHYSICIANS SHOULD FULLY READ THE PRESCRIBING INFORMATION BEFORE PRESCRIBING HYDROXYCHLOROQUINE.

Side effects include: irritability, headache, weakness, hair lightening or loss, stomach upset, nausea, dizziness, muscle pain, rash, and itching.

Rarely, hydroxychloroquine can affect the bone marrow, leading to reduced white blood cells, platelets, and abnormal red blood cells.

Rare but potentially serious eye toxicity can occur, leading to color blindness and vision loss. Regular eye examinations are necessary.

Patients deficient in a certain enzyme may develop severe anemia. Hydroxychloroquine may worsen psoriasis.

Plaquenil (hydroxychloroquine) Side Effects for Healthcare Professionals

The following adverse reactions have been reported with Plaquenil use:

Blood and lymphatic system disorders: Bone marrow failure, anemia, aplastic anemia, agranulocytosis, leukopenia, and thrombocytopenia.

Cardiac disorders: Cardiomyopathy, prolonged QT interval, ventricular arrhythmias, and torsade de pointes.

Ear and labyrinth disorders: Vertigo, tinnitus, nystagmus, nerve deafness, and deafness.

Eye disorders: Irreversible retinopathy, visual field defects, visual disturbances, maculopathies, decreased dark adaptation, color vision abnormalities, and corneal changes including deposition of drug.

Gastrointestinal disorders: Nausea, vomiting, diarrhea, and abdominal pain.

General disorders and administration site conditions: Fatigue.

Hepatobiliary disorders: Abnormal liver function tests and acute hepatic failure.

Immune system disorders: Urticaria, angioedema, and bronchospasm.

Metabolism and nutrition disorders: Decreased appetite, hypoglycemia, and weight decreased.

Musculoskeletal and connective tissue disorders: Sensorimotor disorder, skeletal muscle myopathy, depression of tendon reflexes, and abnormal nerve conduction.

Nervous system disorders: Headache, dizziness, seizure, ataxia, dystonia, dyskinesia, and tremor.

Psychiatric disorders: Affect/emotional lability, nervousness, irritability, nightmares, psychosis, and suicidal behavior.

Skin and subcutaneous tissue disorders: Rash, pruritus, pigmentation disorders, hair color changes, alopecia, dermatitis bullous eruptions, and photosensitivity.

Report suspected adverse reactions to Concordia Pharmaceuticals Inc. or FDA.

Drug Interactions with Plaquenil (hydroxychloroquine)

• Hydroxychloroquine may increase penicillamine levels, increasing the risk of side effects.
• Combining telbivudine and hydroxychloroquine may increase the risk of muscle pain, tenderness, or weakness.
• Hydroxychloroquine should not be combined with immune-suppressing drugs or live vaccines.

Digoxin

Closely monitor serum digoxin levels in patients receiving combined therapy.

Insulin Or Antidiabetic Drugs

Decrease doses of insulin or antidiabetic drugs when using Plaquenil.

Drugs That Prolong QT Interval And Other Arrhythmogenic Drugs

Avoid administering Plaquenil with drugs that induce cardiac arrhythmias.

Mefloquine And Other Drugs Known To Lower The Convulsive Threshold

Increased risk of convulsions when combining Plaquenil with other antimalarials.

Antiepileptics

Antiepileptic drugs may be less effective when co-administered with Plaquenil.

Methotrexate

Combined use of methotrexate with Plaquenil may increase the incidence of adverse effects.

Cyclosporin

Co-administration of cyclosporin and Plaquenil may increase plasma cyclosporin levels.

The following interactions have been observed with chloroquine phosphate and may also apply to hydroxychloroquine:

Praziquantel

Chloroquine reduces the bioavailability of praziquantel.

Antacids And Kaolin

Reduce absorption of chloroquine; take chloroquine and these agents at least 4 hours apart.

Cimetidine

Cimetidine inhibits the metabolism of chloroquine, increasing plasma levels. Avoid concomitant use.

Ampicillin

Chloroquine reduces the bioavailability of ampicillin.

Summary

Plaquenil (hydroxychloroquine) is used to treat malaria, lupus erythematosus, and rheumatoid arthritis. Common side effects include irritability, headache, weakness, hair lightening or loss, stomach upset, nausea, dizziness, muscle pain, rash, and itching. It is safe for use in pregnant women and may be secreted in breast milk.