T-20, unlike other anti-HIV medications, lessens the ability of HIV to infect certain cells (T cells) in the body. Doctors hope to better treat HIV by adding T-20 to anti-HIV drug combinations that include 1 or 2 nucleoside reverse transcriptase inhibitors (NRTIs) plus a nonnucleoside reverse transcriptase inhibitor (NNRTI) and/or a protease inhibitor (PI).