Substance abuse is the excessive use of a substance, such as drugs or alcohol, which results in clinical and functional impairments. Ongoing substance abuse can cause severe health problems over time, even in previously healthy individuals. These health complications include increased disease risk, difficulty in detecting and diagnosing certain disease states, a reduced inherent ability to recover from certain diseases, and a decrease in the effectiveness of various treatments.
With regard to HIV and AIDS, substance abuse plays a significant factor in infection and disease progression. Although HIV/AIDS can affect anyone, the risk of infection is significantly higher in patients suffering from substance abuse, whether the risk is of direct exposure through needles or increased likelihood of high risk behavior due to loss of judgment. Substance abuse is of primary concern to HIV/AIDS by promoting actions which increase the initial risk of infection. Furthermore, some abused substances can also influence disease progression and interfere with the effectiveness of treatment.