Opioid Substitution Therapy (OST) is a treatment approach for individuals with opioid use disorder. It involves replacing an illegal opioid, like heroin, with a legally prescribed medication, such as methadone or buprenorphine. This helps reduce withdrawal symptoms and cravings, allowing individuals to stabilize their lives and engage in recovery. OST is often part of a comprehensive treatment plan that includes counseling and support services. By providing a safer alternative, it aims to decrease the risks associated with opioid use, such as overdose and infectious diseases. Overall, OST can improve the quality of life for those struggling with addiction.