“My pharmacy has been unable to get acyclovir for more than two months,” Wes Nyberg, an HIV-positive San Diego resident, told POZ in February. Others around the country reported similar shortages—and as POZ went to press, the deficiency persisted.

The problem was not minor: According to Anna Wald, MD, a virologist at the University of Washington in Seattle, about 70 percent of people with HIV also have herpes (HSV-2). HIV makes people more vulnerable to herpes, and the two viruses egg each other on. Conversely, however, well-controlled herpes can slow HIV progression. No wonder so many coinfected people take the herpes-fighting generic acyclovir, either daily or just during herpes flare-ups.

But in late 2009 and early 2010, pharmacists across the country reported the acyclovir shortages. “It became an acute problem back in December,” says Sorin Kazangian, PharmD, of Discount Medical Pharmacy in LA, where about 80 percent of customers have HIV. Nyberg and others temporarily switched to Valtrex, which Wald calls therapeutically equivalent to acyclovir. But the difference comes at the cash register: a Valtrex co-pay of up to $50 instead of the $10 for generic acyclovir.

While some pharmacists and consumers suspected a pharma conspiracy, the Food and Drug Administration offers this explanation of the acyclovir crunch. Manufacturing problems at Apotex, a major generics maker in Canada, temporarily froze its U.S.-market drugs, including acyclovir. The big generics maker Teva then found its own supplies depleted when it had to cover Apotex’s shortfall. Teva called the shortages temporary, but at press time the FDA shortage list still included acyclovir.

Complicating matters, the long-awaited generic version of Valtrex, valacyclovir, had yet to be widely available. The manufacturer, Ranbaxy Pharmaceuticals, was promising to ramp up production, but at press time, at least some pharmacies still couldn’t get it.

The takeaway? If you are ever unable to get acyclovir, try generic Famvir (famciclovir, which Wald also dubs therapeutically equivalent). Or choose Valtrex, knowing that the higher price will be temporary. Bob Munk, an HIV-positive Santa Fe AIDS activist, says his doc switched him from twice-daily acyclovir to once-daily Valtrex: “Great for the schedule, bad for the co-pay!”