SNRIs, or serotonin-norepinephrine reuptake inhibitors, are antidepressants that increase the availability of two chemical messengers, serotonin and norepinephrine, by blocking their reuptake into nerve cells. The group includes venlafaxine (Effexor XR), desvenlafaxine (Pristiq), duloxetine (Cymbalta) and levomilnacipran (Fetzima). At lower doses venlafaxine acts mostly on serotonin, with norepinephrine effects emerging as the dose rises. Duloxetine affects both from the start. The added norepinephrine activity may help with energy, concentration and physical pain, which is why duloxetine is also approved for diabetic nerve pain, fibromyalgia and chronic musculoskeletal pain.
SNRIs are used for major depression, generalized anxiety disorder, panic disorder and social anxiety, and they are a common next step when an SSRI has not worked. Side effects overlap with SSRIs, including nausea, sweating, insomnia and sexual side effects, with the addition of a possible small rise in blood pressure at higher doses, so your provider may check it at visits. Venlafaxine in particular can cause noticeable discontinuation symptoms if doses are missed or stopped abruptly, which makes a gradual taper important. Like SSRIs, SNRIs take several weeks to reach full effect. They are often chosen for people whose depression comes with fatigue or chronic pain, and they can be combined with other agents in an augmentation plan. Stedfast Psychiatry providers monitor response with standardized scales at each follow-up.