An openly gay San Francisco supervisor announced this week that he's taking Truvada to reduce the risk of contracting HIV.

Supervisor Scott Wiener is among the first elected officials to disclose that he's participating in the treatment known as pre-exposure prophylaxis, or PrEP.

The daily regimen was approved by the Food and Drug Administration in 2012 and some researchers believe it may reduce the risk of infection by 99 percent, when taken as prescribed.

Critics, however, say it's too early to embrace Truvada and some complain about its toxic side effects.

Wiener said that “a much larger segment of gay men should be taking a close look at PrEP.”

Supervisor David Campos has proposed subsidizing the drug to HIV-negative residents who can't afford it. Truvada lists for over $1,000 a month.

New York is counting on the drug to help it to sharply cut new infections.

(Related: New York's Andrew Cuomo declares war on state's AIDS epidemic.)