Naltrexone is a medication primarily used in the treatment of opioid dependence and alcohol use disorder. It works by blocking the effects of opioids and alcohol in the brain, reducing cravings and preventing relapse. Naltrexone is available in both oral and extended-release injectable formulations. Additionally, low-dose naltrexone (LDN) is sometimes used off-label for conditions such as autoimmune diseases, chronic pain, and fibromyalgia. Naltrexone should be used under medical supervision, and its effectiveness may vary depending on individual circumstances and adherence to treatment.