The HIV drug tenofovir (in Viread, Atripla and Truvada) can affect kidney function in people who've taken HIV meds before and have underlying kidney problems.

But what about people on their first HIV combo? Researchers at Johns Hopkins University School of Medicine in Baltimore recently reviewed three years of tenofovir trials conducted by the drug's manufacturer, Gilead Sciences.

The review found tenofovir “very safe in [treatment naive] patients,” says lead author Joel Gallant, MD, professor of medicine at Hopkins. “Kidney toxicity is unlikely in people with normal kidney function taking tenofovir in a first regimen,” Dr. Gallant says. “[But] kidney function should be monitored no matter what drugs you're taking.” Temporary conditions affecting the kidney, such as an acute illness causing dehydration, or high doses of ibuprofen or other drugs, can increase tenofovir kidney toxicity risk.

“While I avoid tenofovir in patients with impaired kidney function, I feel comfortable using it in people with normal function [even if they] have a family history [of the disease] or other risk factors such as diabetes or high blood pressure,” Gallant says. “I can monitor their kidney function and change drugs if necessary.”

Gallant is the author of 100 Questions and Answers About HIV and AIDS (Jones and Bartlett, $20).