Meds for the morning after.

A new study underscores the success of post-exposure drug treatment for HIV prevention

There are dozens of reasons gay men and lesbians may turn to HIV postexposure prophylaxis--the so-called morning-after pill--following possible exposure to the virus. But until now there was no evidence that a short course of antiretroviral drugs might be effective in preventing infection after sexual exposure.

Researchers at the University of California, San Francisco, put nearly 400 people--94% of whom had reported engaging in unsafe sex--on a four-week PEP regimen within 72 hours of possible HIV infection. After six months, none of them was infected. The results of the study were published in March's Journal of Infectious Diseases.

But don't let this study fool you into thinking PEP is an easy fix for any unsafe slip-ups. The necessary drug regimen could carry with it four weeks of persistent nausea and diarrhea. In fact, lead researcher James O. Kahn, a UCSF associate professor of medicine, says PEP should never be considered a substitute for safer sex. "That would be a disaster, a huge mistake," he says. "We want to help people develop safe habits so that medication is not necessary in the future."