Effexor is the brand name for the medication venlafaxine. This drug is known as a serotonin and norepinephrine reuptake inhibitor, which means that it increases the levels of chemicals which are involved in controlling mood in the brain. It can be used to treat depression and other psychiatric disorders, but it also causes many different side effects.
Gastrointestinal Effects
Effexor has the ability to cause disruption of the gastrointestinal system, RxList explains. This can result in patients experiencing nausea and having a loss of interest in food, sometimes resulting in weight loss. Patients may also experience dry mouth as a result of using Effexor. Some patients may also experience diarrhea, constipation and nausea, Drugs.com explains.
Psychological/Neurological Effects
Patients taking Effexor may also experience insomnia and anxiety, EMedTV explains. In addition to these psychological side effects, Effexor can result in unusual dreams, agitation and unusual thoughts. Patients may also become confused and experience poor reflexes and imparied muscle coordination. Other neurological side effects include a tremor, muscle twitches and tingling or numbness.
Cardiovascular Effects
Effexor can also lead to certain side effects relating to the cardiovascular system. In some cases, patients may experience a rapid heart rate or increased blood pressure. Other patients experience a condition known as orthostatic hypotension, in which the blood pressure drops when standing rapidly from a sitting or reclining position, resulting in a light-headed feeling or dizziness.
Urinary Effects
Effexor can also affect the urinary system. Many patients experience a loss of libido and can experience diminished or delayed orgasm. Patients can also experience a sensation of needing to urinate frequently combined with problems urinating.
Allergic Effects
Sometimes, the immune system will react abnormally to Effexor, resulting in an allergic reaction. The mildest cases cause only hives or a rash. More advanced allergic reactions can result in the finger, face, lips and tongue swelling. Anaphylaxis, which is the most extreme type of allergic reaction, can result in shortness of breath, difficulty swallowing, chest tightness and hoarseness.
Serotonin Syndrome
Effexor can also result in a dangerous condition known as serotonin syndrome, EMedTV explains. Serotonin syndrome is marked by confusion, hallucinations, overactive reflexes and seizures. In addition, patients may experience an elevated heart rate, nausea, vomiting, shaking, fever and sweating. Patients may lapse into a coma, which may be fatal.
