Most of the AIDS diseases involve some degree of immune suppression which may be produced by many different factors. Drug use, particularly heroin, is one. Recreational drugs are commonly used by active homosexuals. Use of alcohol, heroin, cocaine, marijuana, valium, and amphetamines can all be found as part of the life histories of many AIDS patients. When combined with regular and prolonged malnutrition, as is done with many homosexuals and many heroin addicts, this can lead to complete immune collapse. Antibiotics, when used heavily or over long periods, also wear down the immune system. Repeated an constant infections may eventually overload the immune system, causing its failure. Worse still is the simultaneous infection by two or more diseases. Procedures and practices traumatic to the body ("fisting" in the case of homosexuals) can play a major role in weakening the immune system. Many forms of surgery are immunosuppressive because of the trauma itself, or due to anaesthesia, or from immunosuppressive chemotherapy, or even from blood transfusion itself. Immune suppression is in fact proportional to the volume of transfused blood.