HIV treatment reduces the amount of HIV in the blood (viral load). Taking your HIV medicine as prescribed will help keep your viral load low. HIV treatment can make the viral load very low (viral suppression). Viral suppression means having less than 200 copies of HIV per milliliter of blood. HIV treatment can make the viral load so low that a test can’t detect it (undetectable viral load). If your viral load goes down after starting HIV treatment, that means treatment is working. Continue to take your HIV treatment as prescribed. If you skip your HIV treatment, even now and then, you are giving HIV the chance to multiply rapidly. This could weaken your immune system, and you could become sick. Getting and keeping an undetectable viral load (or staying virally suppressed) is the best way to stay healthy and protect others. HIV treatment prevents transmission to others. If you have an undetectable viral load, you will not transmit HIV through sex. Having an undetectable viral load likely reduces the risk of HIV transmission through sharing needles, syringes, or other injection equipment (for example, cookers), but we don’t know by how much. Having an undetectable viral load also prevents perinatal transmission. If a person with HIV takes their HIV medicine as prescribed throughout pregnancy and childbirth and gives HIV treatment to their baby for 4 to 6 weeks after birth, the risk of transmission can be 1% or less. Having an undetectable viral load greatly reduces the risk of transmitting HIV through breastfeeding but doesn’t eliminate the risk. The current recommendation in the United States is that parents with HIV should not breastfeed their babies. Taking your HIV medicine as prescribed helps prevent drug resistance. Drug resistance develops when people with HIV don’t take their pills as prescribed or miss their shots. The virus can change (mutate) and may limit your options for successful HIV treatment. If you develop drug resistance, it will limit your options for successful HIV treatment. Drug-resistant strains of HIV can be transmitted to others.