Venlafaxine, sold under the brand name Effexor, is an anti-depressant medication. Effexor is a serotonin-norepinephrine reuptake inhibitor, or SNRI. It's a class of drugs that target the neurotransmitters serotonin and norepinephrine in your brain. Although Effexor can cause weight gain, it is less likely to cause weight gain compared to other anti-depressants. Consult your physician if you are experiencing any side effects while on Effexor.
How Effexor Works
Effexor is used to treat major depression. An imbalance of a neurotransmitter, like serotonin or norepinephrine, can cause depression. In healthy adults, when a message travels down one nerve cell to another, neurotransmitters are released into the space between the nerve cells. When enough neurotransmitters are released to reach the second nerve cell, the message continues on its way. The initial nerve cell reabsorbs any remaining neurotransmitters in a process called reuptake. Effexor, and other SNRIs, help to block the reuptake of serotonin and norepinephrine so that more will remain in the gap between nerve cells, which helps to ensure that messages continue to travel through the brain.
Effexor and Weight Gain
Although Effexor is less likely to cause weight gain than other anti-depressants, it is still possible to see an increase in weight while taking the medication. Weight gain was a reported side effect in at least 1 percent of the people taking the medication, however the exact percentage amount is not known, according to eMedTV.com. It is unclear if Effexor causes the weight gain or if the weight gain is a symptom of depression. One of the criteria of major depression, according to the "Diagnostic and Statistical Manual of Mental Disorders," is a significant change in weight.
Effexor and Metabolism
The role of most antidepressants is still largely unknown, but some research suggests that antidepressants can affect metabolism. A study published in “L'Encephale” reviewed the past research on different psychotropic drugs and how they interact with metabolism. Researchers speculate that anti-depressants, including Effexor, might interfere with central nervous functions that regulate energy balance. The research also speculates that some anti-depressants decrease the resting metabolic rate. However, the researchers indicate that more studies need to be done on metabolism and anti-depressants to learn the exact role medication plays in the metabolic process.
Effexor Side Effects
Effexor has been studied in a number of clinical trials for side effects. Some common side effects of the medication include nausea, headaches, drowsiness, dizziness and insomnia. Other side effects include changes in appetite and anxiety and sexual and gastrointestinal problems. Effexor can potentially have serious side effects. It can increase blood pressure, cause high cholesterol, cause confusion and strange thoughts. In children, adolescents and young adults, Effexor increased the risk of suicidal thinking and behavior compared to placebo.
- Diagnostic and Statistical Manual of Mental Disorders; American Psychological Association; 2000
- eMedTV; What Is Effexor?; Kristi Monson
- Drugs.com: Effexor
- “L'Encephale”; Psychotropic Drugs Induced Weight Gain; O. Ruetsch, et al.; July-August 2005