Drug use, including alcohol, increases the chance that people will not protect themselves during sexual activity. Someone who is trading sex for drugs might find it difficult to set limits on what they are willing to do. Anyone using drugs is less likely to remember about using protection, or to care about it. It is very important to take every dose of anti-HIV medications. Drug use is linked with poor adherence, which can lead to treatment failure.
Some street drugs interact with medications.
The liver breaks down some medications used to fight HIV, especially the protease inhibitors and the non-nucleoside analog reverse transcriptase inhibitors. It also breaks down some recreational drugs, including alcohol. This can lead to a serious overdose of the medication or of the recreational drug. An overdose of a medication can cause serious side effects. An overdose of a recreational drug can be deadly.