Hydroxychloroquine is a medication commonly prescribed for autoimmune conditions such as lupus and rheumatoid arthritis. Historically, it was also used to prevent and treat malaria. While generally considered well-tolerated, it is important for individuals taking this medication to be aware of certain rare but serious side effects.
Ocular and Retinal Toxicity
One significant concern with long-term hydroxychloroquine use involves the retina. This condition, known as retinopathy, refers to damage to the light-sensitive tissue at the back of the eye. Early stages of retinal damage may not cause noticeable symptoms, making regular monitoring important. As the condition progresses, individuals might experience changes in vision, such as difficulty reading, blurred vision, or the development of blind spots in their visual field.
A distinct pattern of retinal damage is referred to as “bull’s-eye maculopathy.” This describes a ring-shaped area of damage around the macula, the central part of the retina responsible for sharp, detailed vision. Retinopathy linked to hydroxychloroquine is typically associated with long-term use, often exceeding five years, and higher cumulative doses of the medication. The changes to the retina, once established, can be progressive and irreversible, underscoring the need for early detection.
Cardiac Complications
Hydroxychloroquine has been associated with rare but serious complications affecting the heart muscle. Cardiomyopathy, a disease that weakens and enlarges the heart muscle, can make it harder for the heart to pump blood effectively. This impaired pumping ability can lead to symptoms like shortness of breath, swelling in the legs or ankles, and fatigue.
The medication can also influence the heart’s electrical rhythm, leading to cardiac conduction issues. These problems can manifest as a fast or irregular heartbeat, palpitations, dizziness, or even fainting spells. In very rare instances, these cardiac effects, including QT prolongation (a delay in the heart’s electrical recharging), have been linked to more severe outcomes such as heart failure or sudden cardiac death.
Other Serious Systemic Reactions
Hydroxychloroquine can, in rare instances, lead to other serious systemic reactions. Severe skin reactions, though infrequent, can be profound. These include conditions like Stevens-Johnson syndrome (SJS) and Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), which present as severe rashes accompanied by systemic symptoms such as fever, blistering, and peeling of the skin.
Blood disorders represent another rare category of serious side effects. Hydroxychloroquine use has been linked to bone marrow depression, which can result in conditions such as agranulocytosis, a significant decrease in white blood cells. This reduction can severely compromise the body’s ability to fight infections. Other potential blood issues include aplastic anemia, where the bone marrow fails to produce enough new blood cells, leading to increased risk of bleeding or fatigue.
Neuromuscular issues, affecting muscles and nerves, can also occur rarely. These may include myopathy, characterized by muscle weakness, cramps, or stiffness. Additionally, neuropathy, which involves damage to peripheral nerves, can lead to symptoms such as tingling sensations or nerve pain in the hands or feet. These effects can impact an individual’s mobility and sensation.
Risk Factors and Proactive Monitoring
Several factors can increase the risk of developing rare but serious side effects. A higher daily dosage, particularly exceeding 5 mg/kg of ideal body weight or a maximum of 400 mg daily, elevates the risk. The duration of therapy also plays a role, with risks increasing significantly after more than five years of continuous use. Pre-existing kidney or liver disease can impair the body’s ability to clear the drug, potentially leading to higher drug levels and increased toxicity. Individuals over 60 years of age or those with underlying retinal or heart conditions may also be at higher risk.
Proactive medical monitoring is crucial for managing these risks. Regular eye examinations are strongly recommended, typically involving a baseline exam within the first year of treatment, followed by annual screenings, especially after five years of therapy. These eye exams often include specialized tests like spectral-domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF), which can detect subtle changes in the retina before symptoms appear. For cardiac health, while routine electrocardiograms (EKGs) are not always standard for all patients, they may be considered at baseline, particularly if there are pre-existing heart conditions or concerns. Periodic blood work is also advised for individuals on long-term therapy to monitor for potential blood disorders.