Ivermectin was the sixth most popular topic on Twitter in the U.S. on Tuesday afternoon, with more than 46,000 tweets, suggesting that many users were under the impression that the term had been previously censored on the platform.

The Tesla founder, the world’s richest person, has said his purchase of Twitter was motivated by his dedication to promoting free speech. Musk and others have criticized Twitter for its content moderation policies.

“Ivermectin, ivermectin, ivermectin…just checking,” tweeted one user, with another posting, “Can I tweet the word ivermectin now? Is it finally acceptable?”

In fact, the name of the treatment has never been banned, although it has been just one of a number of popularly cited treatments for COVID-19 that has remained controversial throughout the global pandemic.

There have been no large-scale studies showing that the drug is effective against coronavirus, or offers any substantial health benefits in treating a COVID-19 infection.

Coronavirus Controversy

Originally used in veterinary medicine to treat heartworm, ivermectin tablets for humans can be used for intestinal parasites, as well as for skin conditions such as rosacea, according to the U.S. Food and Drug Administration (FDA).

The FDA notes on its website however that it “has not authorized or approved ivermectin for use in preventing or treating COVID-19 in humans or animals,” going on to state that large doses of the drug can be dangerous.

A study of 490 Malaysian COVID-19 inpatients published in the Journal of the American Medical Association in February found that treatment with ivermectin during early illness did not prevent progression to severe disease.

The World Health Organization (WHO) also says the evidence for using ivermectin to treat COVID-19 is “inconclusive” and advises that the drug only be used in clinical trials.

The drug has nevertheless been touted by many supporters of former President Donald Trump, with many taking to Twitter again on Tuesday to promote it.

Trump himself has been a proponent of a number of other unproven treatments for the coronavirus, including hydroxychloroquine, a medicine used to treat malaria and autoimmune disease.

The WHO found that in more than 30 clinical trials of more than 10,000 COVID-19 patients the drug failed to reduce mortality, and could cause a number of serious side effects if used to treat the virus.