Paroxetine (Paxil^®) is a drug that is used to treat depression, social anxiety disorder, obsessive-compulsive disorder (OCD), panic disorder, and other conditions within the brain. It belongs to a class of drugs called selective serotonin reuptake inhibitors, or SSRIs for short. SSRIs balance the levels of a specific chemical (serotonin) in the brain. Paroxetine comes in tablet and suspension (liquid) form and is usually taken once a day. Some common side effects that may occur with this drug include ejaculation problems, dry mouth, and insomnia.