Serotonin-norepinephrine reuptake inhibitors (SNRIs) are a class of medications primarily used to treat depression and anxiety disorders. They work by increasing the levels of two important neurotransmitters in the brain: serotonin and norepinephrine. By preventing the reabsorption (or reuptake) of these chemicals, SNRIs help improve mood and emotional balance. Common examples of SNRIs include venlafaxine and duloxetine. These medications can also be effective for conditions like chronic pain and fibromyalgia. While generally well-tolerated, they may cause side effects such as nausea, dizziness, or changes in blood pressure, and should be used under medical supervision.