Venlafixine, brand name Effexor, is a drug prescribed for depression and a number of other psychiatric conditions. A high dose of venlafaxine may have a stronger intended clinical effect, but also a higher incidence of side-effects. If a high ingested dose of venlafaxine means an accidental or intentional over-dose as in a suicide attempt, contact emergency services immediately. A physician will weigh the benefits, risks and side-effects before prescribing the medication. It is important to discuss and understand these risks and benefits.
Gastrointestinal Side-Effects
Many of the side effects of Effexor are gastrointestinal. According to the Pfizer, the incidence of nausea is 21 to 35 percent. Eight to 20 percent of people experience a decreased appetite. Other gastrointestinal side effects may include constipation, nausea and vomiting.
Nervous System and Psychological Effects
About one-third of people experience headache as a prominent side-effect of Effexor. Insomnia is experienced by 15 to 20 percent of people, and dizziness in slightly less, says Pfizer. Agitation occurs in about 3 percent of the people. Other neurological or psychological side-effects may include vivid dreams, apathy, anxiety, impulsive actions and memory loss.
Cardiovascular Side Effects
There are a few side effects of Effexor involving the heart or blood vessels. High blood pressure occurs in about 5 percent of people, according to Pfizer. A drop in blood pressure when moving from lying down to sitting or standing can also occur, causing lightheadedness.
Sexual Side Effects
Pfizer cites a number of sexual side effects associated with Effexor use. Sexual dysfunction occurs in 14 to 34 percent of people. The medication causes abnormal ejaculation in about 12 percent of patients. Three to 9 percent experience decreased libido.
Some of these side-effects can be alleviated by changing the dose or adding another medication; any changes should be done through consultation with a physician.
References
- Pfizer: Effexor Data Sheet
- "Harrison's Principles of Internal Medicine"; Anthony S Fauci; 17th Ed 2008
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