Oxycodone, sold under the brand name OxyContin (which is the extended release form) among others, is an opioid medication used for treatment of moderate to severe pain, and a common drug of abuse. It is usually taken by mouth, and is available in immediate-release and controlled-release formulations. Onset of pain relief typically begins within fifteen minutes and lasts for up to six hours with the immediate-release formulation. In the United Kingdom, it is available by injection. Combination products are also available with paracetamol (acetaminophen), ibuprofen, naloxone, and aspirin.Common side effects include euphoria, constipation, nausea, vomiting, loss of appetite, drowsiness, dizziness, itching, dry mouth, and sweating. Severe side effects may include addiction, dependence, hallucinations, respiratory depression (a reduction in breathing), bradycardia, and low blood pressure. Those allergic to codeine may also be allergic to oxycodone. Use of oxycodone in early pregnancy appears relatively safe. Opioid withdrawal may occur if rapidly stopped. Oxycodone acts by activating the μ-opioid receptor.