The ads target gay and bisexual men, aiming to get them to file a lawsuit against Gilead.

Facebook has been criticised for allowing adverts to be displayed that claim that PrEP is dangerous. Some of the ads claim that the drug could have significant effects on people’s kidneys or bones.

LGBTQ activists, including from GLAAD have debunked the ads as “factually inaccurate” and added that the adverts could be “convincing at-risk individuals to avoid PrEP, invariably leading to avoidable HIV infections.”

Pre-exposure prophylaxis, more commonly referred to as PrEP, is an anti-retroviral drug taken by HIV-negative people which, if used consistently, can help to dramatically reduce the risk of acquiring the virus.

Both the Centers for Disease Control and Prevention and the US Preventitve Services Task Force recommend PrEP for individuals at risk of acquiring HIV.

The ads seek for people to file lawsuits against Gilead, the company that manufactures PrEP, and claims that the company has prevented the introduction of Descovy, as it wants to make more money out of PrEP.

Speaking to the Washington Post about the danger that the adverts posed, Demetre Daskalakis, the deputy commissioner for the Division of Disease Control at the New York City Department of Health and Mental Hygiene, said: “Four of my seven PrEP patients came in and said, ‘How could you be putting me on this medication that’s so unsafe? My Instagram ads say so.'”

It’s reported that since the ads started appearing in September, they had been viewed millions of times.

Activists attempted to have the ads removed, but Facebook refused saying that the adverts had been verified on its independent fact-checkers. This has led to 50 LGBTQ, HIV and public health organisations to write an open letter denouncing the ads.

Part of the letter reads: “Given the history of how our community was met by deadly indifference during the early years of the AIDS crisis, the refusal to take action is deeply concerning.

“These concerns of the LGBTQ community, AIDS activists, and public health professionals need to be prioritized by Facebook, especially since lives and public health are at stake.”

Speaking to Time, Peter Staley, the founder of PrEP4ALL and a HIV/AIDS campaigner, said: “This is what we fought for.

“And to have a corporate behemoth ignore us and dismiss our concerns reminds me of the walls of intransigence that we hit in the 1980s from the U.S. government and the mainstream press. They just didn’t care that the disease was spreading.

“And they’re hiding behind obscure advertising policies and third party institutions that really know nothing about the complexities of HIV treatment.”

Related: PrEP to be provided for free to uninsured people in United States