Hydro M367 is a prescription medication that contains hydrocodone bitartrate 10 mg and acetaminophen 325 mg. It is used for the management of moderate to severe pain when other non-opioid pain relievers are not sufficient. The tablet is often identified by the imprint “M367” and is commonly known as a combination opioid pain reliever. Hydrocodone is an opioid analgesic that works by binding to opioid receptors in the brain and spinal cord, changing the way the body perceives and responds to pain. Acetaminophen enhances the pain-relieving effect and also helps reduce fever. Together, this combination provides stronger pain relief than either ingredient alone. This medication should be taken exactly as prescribed by a healthcare provider. Because it contains an opioid, it carries a high risk of dependence, tolerance, misuse, and addiction, especially with prolonged use or higher doses. Sudden stopping of the medication after long-term use may cause withdrawal symptoms such as restlessness, muscle pain, insomnia, sweating, and irritability, so dose reduction should always be done under medical supervision. Common side effects include drowsiness, dizziness, nausea, vomiting, constipation, lightheadedness, and sedation. In some cases, it may also cause slowed breathing, especially when taken in high doses or combined with alcohol, benzodiazepines, or other sedatives. Patients are strongly advised to avoid alcohol and other central nervous system depressants while using this medication. Because acetaminophen is part of the combination, excessive use can also lead to liver damage, especially if taken with other acetaminophen-containing products. Patients should carefully follow dosing instructions and not exceed the prescribed amount.