Hydroxychloroquine 200 mg tablets are primarily used to treat autoimmune conditions like lupus and rheumatoid arthritis, and to prevent or treat malaria. Originally developed as an antimalarial drug in the mid-20th century, it became one of the most widely prescribed medications in rheumatology because of its ability to calm an overactive immune system.
Lupus
Hydroxychloroquine is a cornerstone treatment for both systemic lupus erythematosus (SLE) and chronic discoid lupus erythematosus, a form that primarily affects the skin. Most people with lupus take it continuously, often for years or decades. The typical dose ranges from 200 mg once daily to 400 mg daily, taken as a single dose or split into two.
For lupus patients, the drug helps reduce flares, joint pain, skin rashes, and fatigue. It also appears to have protective effects beyond symptom control: it lowers certain inflammatory markers, reduces immunoglobulin levels, and helps regulate the overactive immune signaling that drives the disease. Many rheumatologists consider it the one medication that nearly every lupus patient should be on, regardless of disease severity.
Rheumatoid Arthritis
In rheumatoid arthritis, hydroxychloroquine works as a disease-modifying drug, meaning it doesn’t just mask pain but actually slows the immune-driven process that damages joints. It’s often prescribed alongside other medications for a combined effect. On its own, it’s considered one of the milder options, which also means it tends to have fewer side effects than more aggressive treatments.
One important thing to know: hydroxychloroquine is not a fast-acting drug. Symptoms may start improving within one to two months, but it can take up to six months to feel the full benefit, according to the American College of Rheumatology. This slow onset catches some people off guard, and it’s worth sticking with the medication long enough to give it a fair trial before concluding it isn’t working.
Malaria Prevention and Treatment
Hydroxychloroquine is still used to prevent and treat malaria, though only in regions where the malaria parasite hasn’t developed resistance to the drug. For travelers heading to those areas, the prevention schedule starts one week before arrival. You take one dose per week during your stay and continue for four weeks after leaving. The weekly adult dose for prevention is 400 mg (salt weight), which equals 310 mg of the active base compound.
For active malaria infections, hydroxychloroquine treats uncomplicated cases caused by all four major species of the Plasmodium parasite. It is not effective against drug-resistant strains, which are common in parts of sub-Saharan Africa and Southeast Asia.
Off-Label Uses
Rheumatologists frequently prescribe hydroxychloroquine for conditions beyond its official approvals. Sjögren’s disease is one of the most common. Multiple international guidelines, including those from the European League Against Rheumatism and the American College of Rheumatology with the Sjögren’s Foundation, recommend it for joint and skin involvement, inflammatory musculoskeletal pain, and fatigue in Sjögren’s patients. The British Society of Rheumatology also suggests a trial for patients with significant fatigue or systemic disease.
Other off-label uses include certain inflammatory skin conditions and other connective tissue diseases where immune overactivity plays a central role.
How It Works in the Body
Hydroxychloroquine quiets the immune system by blocking a specific step in the inflammatory chain. Inside your cells, there are sensors called Toll-like receptors that detect threats and trigger inflammation. In autoimmune diseases, these sensors are essentially stuck in the “on” position, reacting to the body’s own tissues as if they were invaders. Hydroxychloroquine binds to the genetic material in the activation pathway and prevents those sensors from firing, which reduces the production of key inflammatory signals, particularly interferon alpha and tumor necrosis factor alpha.
This mechanism explains why the drug works across several different autoimmune conditions. It’s not targeting one specific disease but rather dialing down a shared inflammatory process.
Eye Screening and Retinal Risk
The most significant long-term concern with hydroxychloroquine is a small risk of retinal toxicity, where the drug gradually damages the light-sensing cells at the back of the eye. This is rare in the first several years of use, but the risk increases with prolonged treatment and higher doses.
The American Academy of Ophthalmology recommends keeping the daily dose at or below 5.0 mg per kilogram of real body weight. For someone weighing 80 kg (about 176 pounds), that means a maximum of 400 mg per day. People who are severely obese may need to start at a lower dose to avoid exceeding this threshold. A baseline eye exam with imaging (OCT and fundus autofluorescence) is recommended soon after starting the drug, with annual screening thereafter. If you have no major risk factors, your ophthalmologist may defer annual screening during the first five years.
Heart Rhythm Considerations
Hydroxychloroquine can affect the heart’s electrical timing, a phenomenon called QT prolongation, which in rare cases leads to dangerous irregular rhythms. This risk is highest when the drug is combined with other medications that have the same effect on the heart, including certain antidepressants, antipsychotics, and antibiotics like azithromycin. People with pre-existing heart conditions, very slow heart rates, or imbalances in calcium, potassium, or magnesium are at higher risk.
A few other interactions are worth knowing about. Hydroxychloroquine can strengthen the effect of diabetes medications, potentially causing blood sugar to drop lower than expected. It may also reduce the effectiveness of anti-seizure drugs. If you take antacids containing magnesium, spacing them at least two hours apart from your hydroxychloroquine dose helps ensure proper absorption.
COVID-19: No Longer Recommended
Hydroxychloroquine received significant public attention during the early months of the COVID-19 pandemic. The FDA issued an emergency use authorization in early 2020 but revoked it that June after determining the drug was unlikely to be effective against the virus. A large randomized clinical trial in hospitalized patients showed no benefit on mortality or recovery time, and the dosing regimens used were found to be insufficient to inhibit the virus. The revocation also cited serious cardiac side effects, kidney injuries, and liver problems observed in COVID-19 patients receiving the drug. Hydroxychloroquine is not approved or recommended for the prevention or treatment of COVID-19.