"In November researchers revealed a encouraging finding http taking a pill can greatly reduce the risk of getting HIV. Now health officials are warning doctors http_cidmma_x that preventing the disease will take more than just writing a prescription. The pill called Truvada http is already on the market for treating HIV infections. But the landmark study http involving  men who have sex with men showed that taking Truvada faithfully can reduce the risk of infection by as much as  percent. That touched off a lot of celebrating. Its the first time anybodys shown that taking a pill can prevent HIV  and it was the first new weapon against HIV unveiled in many years. To make sure it works though the Centers for Disease Control and Prevention http says doctors need to do a number of things  Prescribe Truvada only for men at high risk of getting infected  that is only for men who have sex with men those who have multiple sex partners and those who live in areas where theres a lot of HIV circulating.  Test patients before prescribing it to make sure theyre not already infected. Thatll help avoid creating viruses resistant http to the drug when patients miss doses. For the same reason patients should get an HIV test periodically while on the drug.  Counsel patients on Truvada to use condoms faithfully because the drug isnt a sure bet against the virus.  Above all tell patients they must take the drug every day  not just when theyve had risky sex. Article continues after this message from our sponsor The study makes that last point very clear. Overall men who took Truvada had a  percent lower risk of HIV infection. But those who said they took the drug at least  out of every  day had a  percent lower risk. That doesnt tell the whole story. When researchers tested the blood of patients for traces of Truvada they found many who claimed to have taken the pill regularly werent telling the truth. Among those whose tests showed they really did take it every day the risk of HIV infection was  percent lower than those not on the drug. Theres one other thing the CDC says. Make sure patients understand that warding off HIV isnt cheap. Each pill currently costs http around  which adds up to more than  a year. Some insurers might pay but some might balk."