National and local HIV/AIDS organizations say a series of advertisements on Facebook present misleading—and potentially dangerous—information about HIV prevention. But despite their concerns, Facebook has continued to run the ads.

A story published Monday by the Washington Post details how Facebook ads purchased by personal injury law firms contain incorrect messages about Pre-exposure prophylaxis (PrEP), a daily medication people can take to greatly reduce their risk of contracting HIV. The ads, which appear to target members of the LGBTQ+ community, are meant to recruit current PrEP users into class-action lawsuits against pharmaceutical companies that make PrEP medications. The ads specifically name Truvada, a PrEP manufacturer.

According to an open letter to Facebook signed by 52 different HIV/AIDS organizations from across the country, these ads suggest that using PrEP is dangerous for HIV-negative people, “despite numerous studies underscoring the safety of [PrEP] in HIV-negative users.”

One of the letter’s signatories is Cascade AIDS Project (CAP), a nonprofit that provides HIV/AIDS prevention and support services in Oregon and Southwest Washington. Peter Parisot, CAP’s chief of staff, said that people have reached out to CAP and its LGBTQ+ health clinic, Prism, with questions about PrEP’s safety after seeing the ads on their Facebook feeds.

“People were concerned about it when they started running the ads,” Parisot said. “But there are no real significant dangers, at least not in the way they were presented in these ads, to people who are HIV-negative.

The confusion comes from the fact that Truvada is a drug that can be used both as PrEP for HIV-negative patients, and as an antiviral medication for people living with HIV. Parisot said that while Truvada can cause some dangerous side-effects in HIV-positive people who take it in combination with other drugs, the ads’ focus on dangers posed to HIV-negative PrEP users was false.

The outcome of these misleading ads, Parisot said, is that more people are confused about how PrEP works, and may be discouraged from taking it for HIV prevention. That’s especially concerning because the populations most at-risk for contracting HIV—people of color, LGBTQ+ people, and homeless people—already “experience the most barriers to accessing health care,” he said.

“We are very close to being able to end the HIV epidemic, but PrEP is an important part of our strategy,” Parisot added. “To create fear among people who are already experiencing higher disparities in accessing health care is counter-productive.”

The letter CAP signed on to said Facebook had so far been unresponsive to HIV/AIDS organizations’ concerns, despite the fact that Facebook claims to pay attention to “organizations with particular expertise” when considering the appropriateness of an ad.

“We are the organizations with ‘particular expertise,’” the letter reads, before demanding that Facebook remove the ads on the grounds that they are detrimental to public health.

Parisot said that to his knowledge, Facebook has yet to respond to the letter.

“We would love to see Facebook and other media outlets take these ads more seriously,” he said, “because there are people’s lives at stake.”