Effexor (venlafaxine) is a prescription medication used to treat major depressive disorder, generalized anxiety disorder (GAD), social anxiety disorder and panic disorder. It is a serotonin-norepinephrine reuptake inhibitor (SNRI), and acts on two chemicals found in the brain, serotonin and norepinephrine. It alleviates symptoms of depression and anxiety by normalizing the levels of these two chemicals. Effexor can produce many side effects and has the potential to cause withdrawal symptoms. It is important to have a discussion with your physician before the initiation of treatment.
Common Side Effects
Two major side effects of Effexor are headaches and nausea. Other side effects such as dizziness, dry mouth and difficulty sleeping are less common but still occur in about 15 percent of individuals. About 14 percent of people experience loss of appetite that could lead to weight loss. Constipation, nervousness, abnormal dreams, sweating and muscle weakness are other possible side effects of Effexor.
Hypertension
Hypertension, or high blood pressure, is a potential side effect of Effexor. For this reason, it is important to inform your physician if you have or ever had hypertension. The Drug Information Handbook explains that this effect is dose related. About 3 percent of individuals might experience increased blood pressure when the dose is less than 100mg per day. If the dose exceeds 300mg per day, hypertension occurs in 13 percent of people. If you experience heart palpitations or chest pain, this might be a sign of increased blood pressure and you should stop the medication and call your doctor.
Sexual Side Effects
Sexual side effects are not uncommon with Effexor. It can cause a decrease in sexual desire, called libido. Effexor has also been associated with delayed ejaculation or abnormal orgasm in about 10 percent of people, and even impotence or lack of an orgasm in up to 9 percent. If these side effects pose a major concern, talk to a health care provider.
Wtihdrawal Symptoms
Effexor should not be abruptly discontinued without tapering off first. This means that the dose is reduced over time to avoid severe withdrawal symptoms, also called discontinuation symptoms. Your physician will decide the best way to taper your dose. Symptoms include anxiety, agitation, changes in mood, imbalance, and difficulty sleeping. Flu-like symptoms, such as headaches, body aches, and cough, are also common upon the discontinuation of Effexor. Sensory disturbance, nightmares, and electrical shocks in the brain and body have also reported by many individuals. These symptoms are usually mild and last about two weeks. If you experience severe effects, speak with your physician because you might need to be tapered off slower or for a longer period of time.
References
- "Drug Information Handbook 15th Edition";; Charles F. Lacy, RPh, PharmD, FCSHP, Lora L. Armstrong, RPh, PharmD, BCPS. et al; 2007
- Effexor XR: Managing Discontinuation
- Pfizer; Effexor XR Patient Package Insert
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