What is Effexor (venlafaxine)? What are the side effects of Effexor?
Effexor (Venlafaxine) is an antidepressant, belonging to the serotonin-norepinephrine reuptake inhibitor (SNRI) class of drugs, used for the treatment of depression and anxiety disorders.
The drug, currently marketed by Pfizer, is the one of the most commonly prescribed antidepressants in the U.S.
As an SNRI, Effexor works by increasing and regulating the levels of two different neurotransmitters in the brain: norepinephrine and serotonin.1
These two neurotransmitters are thought to play an important role in controlling people's happiness and feelings of well-being.
At low doses Effexor inhibits serotonin reuptake and at higher doses inhibits both serotonin and noradrenaline reuptake.
This Medical News Today information article provides details on the medical uses of Effexor, the precautions and side effects associated with its use, and how sudden discontinuation of Effexor can result in withdrawal problems.
Medical uses of Effexor
Venlafaxine was originally marketed by Wyeth. The company first launched the immediate-release formulation of the drug into the American market in 1993, for the treatment of depression.2
The extended-release (XR) formulation of Effexor was approved by the U.S. Food and Drug Administration (FDA) a few years later, in 1997.2
- Effexor® (venlafaxine HCl) Tablets are indicated for the treatment of major depressive disorder.
- Effexor XR® (venlafaxine HCl) Extended-Release Capsules are indicated for the treatment of major depressive disorder, generalized anxiety disorder (GAD), social anxiety disorder (SAD), and panic disorder (PD) with or without agoraphobia.3
Some doctors may prescribe the drug "off label" for the treatment of diabetic neuropathy and migraine prophylaxis. Research published in Headache: The Journal of Head and Face Pain concluded that "venlafaxine was more effective than placebo and was safe and well tolerated as migraine prophylaxis."4
Several studies have examined the efficacy of Effexor for treating depression. A research review of the "antidepressant efficacy of venlafaxine", published in Depression and Anxiety, concluded that "venlafaxine is a unique antidepressant medication with well documented efficacy and safety in the acute treatment of major depressive disorder."5
Effexor is thought to be just as effective (if not more) as SSRIs, including Zoloft (sertraline). A randomized trial of sertraline versus venlafaxine XR in major depression revealed that "sertraline and venlafaxine XR demonstrated comparable effects on quality of life and efficacy in treatment of major depression".6
Effexor is commonly prescribed for anxiety (particularly when SSRIs fail to work), its efficacy is well established. The authors of a double-blind study, which included a total of 271 participants with generalized social anxiety disorder, said "venlafaxine ER is safe, well tolerated, and efficacious in the short-term treatment of generalized social anxiety disorder."7
Effexor is effective at reducing symptoms of anxiety among people with or without depression. Research published in the British Journal of General Practice concluded that "venlafaxine was efficacious in the treatment of patients with GAD with and without depression over a 24-week period."8
Before taking Effexor, patients should discuss their medical history with their doctor to determine whether the drug is appropriate.
In some cases, Effexor may worsen depression and even cause suicidal thoughts. If you start experiencing any of these effects it is important to contact your doctor immediately.
Effexor should not be taken by patients with seizure disorders or those who are allergic to its active ingredients, which include: gelatin, titanium dioxide, hypromellose, iron oxide, ethylcellulose, and cellulose. In addition, patients on MAO inhibitors (such as Parnate and Nardil) should not take Effexor.
The Canadian Medical Association Journal (CMAJ) published a study suggesting that pregnant women who take Effexor may be at a higher risk of miscarriage. Therefore, the drug should only be taken by pregnant women if absolutely necessary.
As the drug can pass into breast milk, mothers taking Effexor should talk to their doctor before breastfeeding.9
Common side effects of Effexor include:10
- Blurred vision
- Dry mouth
- Loss of appetite
- Trouble sleeping
- Excessive sweating
- Irregular bowel movements
Rare side effects of Effexor include:
- High Blood Pressure
- High cholesterol
- Serotonin syndrome
- Mental impairment
- Thoughts of suicide
Video - Effexor withdrawal
Sudden discontinuation of Effexor can result in severe withdrawal symptoms. Just missing one dose may trigger dysphoria (a state of anxiety, depression, or unease), tremor, nausea, headache, hallucinations, paresthesia (a sensation of pricking, tingling, or creeping on the skin), impaired concentration, fatigue, dizziness, and vertigo.
Alexander Glassman, MD, talks about withdrawal syndrome from Effexor.
Written by Joseph Nordqvist
Copyright: Medical News Today
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