Taking EFFEXOR XR can cause a potentially life-threatening problem called serotonin syndrome. The risk of developing serotonin syndrome is increased when EFFEXOR XR is taken with certain other medicines. Venlafaxine, sold under the brand name Effexor among others, is an antidepressant medication of the serotonin–norepinephrine reuptake inhibitor (SNRI) class. [5][9] It is used to treat major depressive disorder, generalized anxiety disorder, panic disorder, and social anxiety disorder. [9] Venlafaxine is used to treat depression. It is also used to treat general anxiety disorder, social anxiety disorder, and panic disorder. Venlafaxine belongs to a group of medicines known as serotonin and norepinephrine reuptake inhibitors (SNRI). Effexor (venlafaxine) is an antidepressant that treats certain mental-health conditions. Common Effexor side effects include drowsiness, nausea, and constipation. They often resolve on their own over time. Other possible Effexor side effects include sweating, dry mouth, and anxiety. Effexor XR (venlafaxine) is used to treat major depressive disorder, anxiety, and panic disorder. Includes Effexor XR side effects, interactions and indications. Venlafaxine (brand name Effexor) is a serotonin–norepinephrine reuptake inhibitor (SNRI) antidepressant used to treat major depressive disorder (MDD) and several anxiety disorders. [1] Find patient medical information for Venlafaxine (Effexor) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings Effexor (Venlafaxine Hydrochloride) may treat, side effects, dosage, drug interactions, warnings, patient labeling, reviews, and related medications including drug comparison and health resources. Effexor, known by the generic name venlafaxine, is in a class of drugs called serotonin norepinephrine reuptake inhibitors (SNRIs). People who are prescribed Effexor often have low levels of serotonin and norepinephrine, chemicals responsible for regulating mood. Venlafaxine is used in adults to treat major depressive disorder.