Heroin is an opioid drug derived from the opium poppy plant that is usually a white or brown powder. It can be injected, snorted, or smoked and is rapidly absorbed into the bloodstream. Heroin use carries health risks like overdose and infection from shared needles. Making clean needles available at pharmacies aims to reduce disease transmission while addiction treatment includes medications like methadone and naltrexone as well as counseling. Brain imaging shows heroin decreases blood flow to the brain, which prolonged use may permanently impact.