What is Hydroxychloroquine Sulfate Used For?

Hydroxychloroquine sulfate has been in the news lately as a possible treatment for coronavirus. So what is it?

Malaria and Autoimmune Treatment

Hydroxychloroquine sulfate is an FDA-approved medication available by prescription only and sold under the brand name Plaquenil, among others. The “sulfate” refers to the addition of sodium to the pill a person takes; you can also get the base pill without the sodium addition. It’s primarily used as a treatment for certain types of malaria, or in some cases a preventive measure against it. It’s also commonly used to treat arthritis. The prescription medication is known as a disease-modifying anti-rheumatic drug (DMARD). It does this by regulating the activity of a overactive immune systems. It has also been shown to improve rashes caused by lupus.

For arthritis, the drug is known to reduce pain and joint stiffness over the long-term. Its effects for both rheumatoid arthritis and lupus typically take weeks to notice.

Hydrocholoroquine is also in the second phase of development as a possible immune modulator for patients with HIV.

Side Effects

Plaquenil does have potential side effects people should be wary of, and can interact with other medications, causing problems. The CDC says the most common adverse reactions to the drug include stomach pain, nausea, vomiting, and headache, all of which can typically be lessened if the pill is taken with a meal. Some people have also reported the medication makes them itchy. Over the long term, hydroxychloroquine has caused an eye condition called retinopathy, which can damage vision by changing the blood flow to the retina. If you have any issues with your liver, kidneys, or retinas, you should not be prescribed this medication.

Association with Coronavirus

President Donald Trump announced in a tweet on March 21st that hydroxychloroquine, combined with an antibiotic called azithromycin, is being tested as a possible way to treat or even prevent against COVID-19, the disease developed after infection with the novel coronavirus. “[They] have a real chance to be one of the biggest game changers in the history of medicine,” the President wrote.

On March 29th, the FDA issued an emergency use-authorization for the decades-old pill, saying that a clinical trial is not feasible. A company called Sandoz donated 30 million doses of hydroxychloroquine to the Strategic National Stockpile, and Bayer donated 1 million doses of chloroquine. The FDA’s authorization allows for a greater number of manufacturers to produce or donate the drug, which the Agency hopes will ensure people who need the medication for arthritis, lupus, and malaria will still have access to it.

The CDC says that although the drug is being studied as a possible treatment or prevention for COVID-19, its efficacy is not yet known.


The CDC says after hearing Paquenil is being tested for its potential to help with the coronavirus, two people ingested a chemical for fish aquariums which contains chloroquine phosphate as an active ingredient. One of the people who took the chemical died; the other became severely ill with gastrointestinal problems and cardiac conduction abnormalities. The product the couple ingested is labeled “for ornamental fish use only.”

NBC reports the couple the CDC referring to is from Arizona. The husband and wife were both in their 60s, and the husband did not survive after eating the fish food. The wife told NBC News she and her husband became extremely sick within 20 minutes of ingesting it.

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