You should start HIV treatment (antiretroviral therapy or “ART”) as soon as you know you have HIV infection…as long as you’re ready to make the commitment. That’s what all current guidelines recommend, including guidelines used in the United States and throughout the world. Changing Recommendations For decades, we based the decision to treat HIV on the CD4 cell count. CD4 cells are blood cells that are damaged by the HIV virus. Over time, the CD4 count (the number of CD4 cells in the blood) declines if the virus isn’t treated. Having a low CD4 count puts you at risk for opportunistic infections: infections by bacteria, viruses, parasites, or fungi that take advantage of your unhealthy immune system. Since most complications of HIV infection tend to occur in people with low CD4 counts, and since early treatment was imperfect, inconvenient, and toxic, we used to recommend treatment only when the CD4 count had fallen to abnormally low level levels. That recommendation has changed in part because treatment today is far more effective, convenient, and safe than it was in earlier years. Most people can be treated with one pill a day, with few side effects, if any. In addition, there is now clear evidence that treatment benefits the individual at any stage, and it also prevents transmission to others. Improving Your Health We now know that HIV is bad for you even if you have a normal CD4 count. With untreated infection, the constant, unchecked replication of the virus creates chronic inflammation and high levels of activity in the immune system that can have negative future consequences. For example, untreated HIV infection may increase the risk for cancer, heart disease, osteoporosis, and cognitive problems, including dementia. Treating HIV brings down inflammation and immune activity, greatly reducing those risks. The START trial was a large international study that compared treatment at normal CD4 counts versus treatment after the CD4 count had declined. It was stopped early because the outcomes with early treatment were clearly better. The study found that the CD4 count was a poor predictor of outcome: even people with normal CD4 counts did better on treatment than off. Preventing the Spread of HIV Another reason to start therapy immediately is to prevent transmission. Effective ART lowers the viral load (the amount of virus in the blood) to levels that can’t be detected by standard laboratory tests. That doesn’t mean you’re cured, but it does mean that you’re far less likely to pass HIV on to someone else. In fact, while we can never prove it’s totally impossible, so far there have been zero HIV transmissions from HIV-positive people with undetectable viral loads, including in three large studies looking at the prevention benefits of ART. Commitment is Key Although experts agree that everyone with HIV should be treated, treatment may not be an emergency. Those with normal or mildly reduced CD4 counts can safely wait until they’re ready to commit. With ART, it’s critical that you take your medications every day. People with depression or substance abuse problems are more likely to miss doses, which can lead to drug resistance. Unless the CD4 count is very low, it’s best to address those obstacles first before staring ART.