Paxil CR controlled-release tablets are used for treating depression, panic disorder, or social anxiety disorder. It may also be used to treat premenstrual dysphoric disorder (PMDD), a severe form of premenstrual syndrome. It may also be used for other conditions as determined by your doctor. Paxil CR controlled-release tablets are a selective serotonin reuptake inhibitor (SSRI). It works by restoring the balance of serotonin, a natural substance in the brain, which helps to improve certain mood problems.