Searching for buy methadone online side effects and warnings often reflects concern about safety, which is appropriate given methadone’s strength. Methadone is a long-acting opioid medication that must be used carefully to avoid complications. Understanding possible side effects helps patients recognize when medical attention may be needed. Common side effects include drowsiness, nausea, constipation, sweating, dry mouth, and dizziness. These effects often improve as the body adjusts to treatment. More serious warnings include slowed breathing, confusion, fainting, or irregular heartbeat, which require immediate medical evaluation. Methadone can interact with alcohol, sedatives, and certain prescription medications. These interactions increase the risk of respiratory depression, making medical supervision essential. Patients should always disclose all medications and supplements they use.