There is now some evidence that using certain recreational drugs can cause significant damage to the immune system and affect HIV disease progression, although it is not possible to distinguish the effects of the drugs themselves from their consequences, including sleep deprivation, poor nutrition and disturbances in adherence to HAART

A 2001 study found that weekly use of either hallucinogens (e.g. ecstasy, LSD) or cocaine strongly and independently predicted death in a cohort of 370 HIV-positive men in a San Francisco cohort: statistically, they were than two and half times more likely to die than men who did not use recreational drugs. Use of hallucinogens was also associated with a faster progression to AIDS (Vittinghof 2001).

Regular drug users report more frequent bouts of colds, flu and unexplainable viruses when they’re taking drugs (and placing great stress on their bodies) than when they’re giving themselves a break. This suggests that damage to the immune system is short term rather than long term. Alcohol and illicit drugs are thought to temporarily reduce the action of your body’s natural killer cells, which are the cells needed to attack infections. It is also likely to have an affect on T-cell / CD4 count if only in the short term.

Whilst the immune system is lowered, opportunistic infections may be more likely, but there is no firm evidence. If these opportunistic infections are serious enough, they could pose a long-term problem for your body’s immune system. However, there is mixed evidence regarding whether use of drugs will speed up the progression of HIV.

In injectors, impurities and bacteria are injected directly into the blood stream, combined with poor diet and so on may be as harmful for the immune system as much as the drugs used.

See also under cocaine above.