HIV Non-Nucleoside and Nucleotide Reverse Transcriptase Inhibitor (NNRTIs) are a structurally-diverse class of drugs which directly bind and inactivate viral Reverse Transcriptase. Unlike NRTIs these drugs do not mimic nuleosides and do not require intracellular modification by host enzymes for activity. NNRTI binding to reverse transcriptase induces conformation changes which deforms the enzyme's active site and thus reverse transcription of the viral genome.
The primary adverse effect of all members of the NNRTI class is skin rash which usually resolves after therapy is ended. In a very small fraction of patients Stevens-Johnson Syndrome (SJS) can result. Uniquely, efavirenz does commonly result in some mild psychiatric adverse effects including insomnia, vivid dreams, and dizziness.