It is now believed that erectile dysfunction drugs may be linked with HIV infections and other sexually transmitted diseases.

Studies have shown that gay men who use erectile dysfunction drugs like Viagra, Levitra, and Cialis are much more likely to practice unsafe sex and to be infected with HIV or another STD. A study conducted in San Francisco showed that 31% of a group of gay and bisexual men reported using Viagra without medical supervision. That study also showed Viagra use was linked with higher rates of risky sexual behavior and STDs. Another study shows that recreational Viagra users were twice as likely as nonusers to be HIV-positive.

Because many gay and bisexual men also use erectile dysfunction drugs in combination with illegal club drugs, Jeffrey Klausner, of the San Francisco Department of Public Health, wants to see less free samples and limited refills of erectile dysfunction drugs given and the drugs classified as controlled substances by the FDA.