Post-Acute Withdrawal Syndrome (PAWS), also known as protracted withdrawal syndrome or prolonged withdrawal syndrome, refers to the symptoms and impairments that can persist for weeks or months after stopping opiates. PAWS affects an estimated 90% of recovering opiate users as well as those recovering from dependence on alcohol or benzodiazepines and is thought to be caused by a range of changes that occur in the brain as a result of substance abuse.