What are the Common Venlafaxine Side Effects?

Venlafaxine is an antidepressant medication prescribed for major depressive disorders, panic, and anxiety. The most common venlafaxine side effects include headache, nausea, insomnia, dry mouth, dizziness and constipation. Those on this medication may also experience nervousness, an increase in blood pressure, fatigue, sweating, loss of appetite, or sexual dysfunction. Cardiac arrhythmia, cholesterol increase, suicidal or homicidal thoughts, hives, mania, or hypomania may also result, although these conditions are rare. Pregnant women and those with compromised liver or kidney function may need dose tapering or reduction.

Doctors may prescribe this medication tothose who suffer from major depression. It may also be used to help people with panic or anxiety disorders. Venlafaxine is sold under the brand names Effexor and Effexor XR as well as generically. The Effexor XR is a sustained-release pill. Both the generic and brand names come in doses of 37.5, 75, 100, and 150 mg.

Combined data for multiple clinical trials by Wyeth Pharmaceuticals revealed that headache was one of the most common venlafaxine side effects; 34% of participants experienced headache while taking this medication. Nausea occurred in 21-35% of the subjects. Insomnia was experienced by 15-23% of people and sexual dysfunction plagued 14-34%. Other side effects reported by Wyeth included dry mouth, loss of appetite, hypertension, dizziness, and excessive sweating.

Less commonly reported venlafaxine side effects were cardiac arrhythmia, i.e., irregular heartbeat, and an increase in total serum cholesterol. Some people on the drug, particularly those under 25 years old, may experience suicidal or homicidal thoughts. For this reason, venlafaxine is not recommended for those under 25. Although hives and allergic reactions are are possible venlafaxine side effects, very few people develop these disorders. Venlafaxine may trigger a manic or hypomanic episode in patients with bipolar disorder.

Research indicates that if a pregnant woman takes venlafaxine extended release during the third trimester of pregnancy, the baby may be born with venlafaxine side effects. These side effects create complications that may require a long period of hospitalization. The baby may need to be on a ventilator, and tube feeding may be necessary. To avoid these problems, a doctor may reduce the dose or temporarily stop the medication during the third trimester.

Venlafaxine's half-life is rather long. Dosage reductions may be necessary to avoid overtaxing already-compromised liver or kidney function. Patients with mild or moderate cirrhosis or liver disease may take 50% less of the medication than healthy people. Reducing the dose by 25%-50% is recommended for those undergoing dialysis. Patients with chronic health conditions generally experience better success with this medication when the dose is individualized.