Written By: Reena Mukamal for the American Academy of Ophthalmology.

Doctors can now use the malaria drugs Plaquenil (hydroxychloroquine) and Aralen (chloroquine) to treat coronavirus. Here’s what eye patients should know.

What are hydroxychloroquine and chloroquine?

• These oral medicines, taken as pills, have been used for decades to treat malaria.
• Hydroxychloroquine is also prescribed for rheumatoid arthritis, systemic lupus erythematosus and other autoimmune disorders.
• The US Food and Drug Administration recently approved these drugs for the emergency treatment of coronavirus disease (COVID-19).

Why use malaria drugs to treat coronavirus?

These drugs may stop the immune system from going overboard in its attack on the virus. Some patients with severe COVID-19 have experienced organ failure and death, apparently because their immune system kept attacking long after the virus was defeated. Hydroxychloroquine helps calm the immune response. That’s why it works so well for autoimmune conditions like lupus.

But it is not yet clear how well hydroxychloroquine and chloroquine work in patients with COVID-19. The drugs appear to protect laboratory-grown cells from coronavirus, but scientists are only beginning to test the drugs for this condition in human clinical trials.

Doctors are not sure what dose is best for patients with COVID-19. For now, the drugs are being prescribed at a higher dose and for a shorter period of time for COVID-19 than for other conditions.

Are hydroxychloroquine and chloroquine safe?

Hydroxychloroquine and chloroquine have been used for decades to treat other health conditions and are generally considered safe. Side effects may include stomach pain, nausea, vomiting, headache and sometimes itchiness.

These drugs can cause health complications, including retinal damage, in some people. Patients with psoriasis, heart arrhythmia, kidney disease or liver disease may be at risk of complications from the drugs. If you have any of these conditions, let your doctor know before starting treatment.

Will these drugs damage my retina?

Patients who rely on these drugs to treat autoimmune conditions such as lupus rarely experience eye damage. Only about 1% to 2% of patients develop retinal problems during a 5-year course of treatment.

“But COVID-19 patients are being given roughly double this dosage, though for only 1-2 weeks,” says ophthalmologist and Academy spokesperson William F Mieler, MD. “Bottom line: If you are older than 50 and have a history of retinal disease, macular degeneration or have been exposed to the breast cancer therapy tamoxifen, discuss these drugs with your doctor. You may be better off considering an alternate treatment.”

What are the signs of retinal toxicity?

Patients who develop retinal damage from hydroxychloroquine and chloroquine may not notice changes in their vision at first. As the damage worsens, symptoms may include:

• Trouble focusing on objects straight ahead, due to loss of central vision
• Difficulty reading
• Weak, blurry or distorted vision
• Changes in color vision

If you notice any visual changes during or after taking these drugs, call your ophthalmologist right away.

How can I get hydroxychloroquine and chloroquine?

These drugs require a prescription from your doctor. It is not safe to use expired medications that you find in your medicine cabinet. Non-prescription substances containing the ingredient chloroquine can also be dangerous.

Due to the recent increase in demand as a result of the COVID-19 pandemic, both of these drugs are in short supply. However, manufacturers of these medicines are rapidly ramping up production.