Did you know this version of Internet Explorer is out of date?

To get the latest experience from our website, please upgrade your browser.

Have a drug or medical device concern?




Effexor is an antidepressant manufactured by Wyeth. When taken by pregnant women, this drug may increase the risk of birth defects.

Effexor (Venlaflaxine) was the first antidepressant in the class of drugs known as serotonin-norepinephrine reuptake inhibitors (SNRIs). It came on the market in 1993 from Wyeth. It was approved by the U.S. Food and Drug Administration to treat major depressive disorder (MDD), generalized anxiety disorder (GAD), social phobia and panic disorders in adults. Pfizer acquired Wyeth in 2009. As an SNRI, Effexor works slightly differently from antidepressants in the selective serotonin reuptake inhibitor (SSRI) class. SNRIs help block the reabsorption of both serotonin and norepinephrine, while SSRIs focus solely on serotonin levels. Scientists believe that maintaining proper levels of serotonin in the brain prevents depression and anxiety, and they also think boosting norepinephrine reduces neuropathic pain. SNRIs were developed after SSRIs, and some studies show they are more effective and cause fewer side effects. Drugs in the SNRI and SSRI classes share some of the most serious complications. Both have been linked to a low risk of life-threatening birth defects in babies of women who take these antidepressants while pregnant. In addition, the FDA has issued its most stringent alerts – black-box warnings -- to warn consumer that the drugs can increase suicidal thoughts and behavior in patients younger than 24. The generic form of Effexor is known as venlafaxine and was approved in June 2010. Prescriptions for Effexor reached 17.2 million in 2007 in the United States, making it the sixth-most-prescribed antidepressant. In 2009, Effexor was the 12th-most-prescribed antidepressant in the United States.

Uses of Effexor

Although Effexor is only approved by the FDA for treatment of four illnesses, doctors do have leeway to prescribe the drug for other conditions, and several uses are growing in popularity. More than a decade ago, Wyeth funded a study that found Effexor significantly reduced the pain associated with diabetic neuropathy. This form of nerve damage is characterized by numbness, tingling and pain in the legs and other extremities. It also causes hypersensitivity to painful stimuli. The study concluded that the extended-release form of Effexor is effective for this condition because it controls the amount of serotonin and norepinephrine in the brain, which affect mood and pain perception. Effexor also has been prescribed off-label to treat debilitating migraines. In April 2012, a neurologist from the Jefferson Headache Center at Thomas Jefferson University in Philadelphia presented new migraine treatment guidelines at the annual meeting of the American Academy of Neurology that formalized Effexor's role. The study was published in the journal Neurology. In addition, women are finding relief from the hot flashes associated with menopause when they are prescribed Effexor. A study published in the Journal of the American Medical Association in 2006 found that women who took the drug reported 60 percent fewer hot flashes. Effexor works best at high doses, though, which means increased side effects, so women have to weigh those concerns against the benefits.

Common Side Effects of Effexor

Patients taking Effexor have reported a host of side effects. Among the most unwanted are those relating to sexual dysfunction: lack of interest in sex, difficulty becoming aroused and the inability to achieve orgasm. A study of Effexor's tolerability profile, which was published in the Journal of Psychopharmacology, noted these percentages of patients who experienced troubling side effects: weight gain (29.6 percent), amnesia (44.4 percent), increased fatigue (48 percent), concentration difficulties (48 percent), and sleepiness (37 percent). Everyday concerns, as reported in a Wyeth study, include nausea, dry mouth, dizziness, insomnia, constipation, nervousness, sweating and blurred vision.

Serious Side Effects of Effexor

Unfortunately, though, those are just the unpleasant side effects. Effexor also has been associated with dangerous and life-altering side effects, such as a low risk of birth defects in babies of mothers who took Effexor while pregnant, suicidal thoughts and behaviors, serotonin syndrome and discontinuation syndrome.

Birth Defects and Miscarriage

The FDA warns pregnant women to weigh the risks and benefits of taking certain medications when they are pregnant. To convey this warning, a letter grade is assigned to prescription medications to denote their safety for use during pregnancy. Like most antidepressants, Effexor has been given a grade C. Drugs with this warning have been proven to harm laboratory animal babies when they are taken in high doses by the mother during pregnancy. SSRIs and SNRIs cannot be tested on human babies for ethical reasons, but birth defects have been noted in babies whose mothers took the antidepressants. In addition, a study published in the May 2010 issue of the Canadian Medical Association Journal found that women who take venlafaxine double their risk of miscarriage.

Persistent Pulmonary Hypertension of the Newborn (PPHN)

The FDA warns consumers about one birth defect, in particular, that is associated with the use of SNRIs such as Effexor – persistent pulmonary hypertension of the newborn (PPHN). PPHN damages a newborn's heart and lungs, making it difficult for the baby to adapt to the environment outside the womb. This condition is rarely detected in utero and in about 10 percent of cases, it is fatal. The FDA requires Effexor to carry a black-box warning to this effect in its labeling information.

SNRIs and SSRIs Share Birth Defect Risks

There have been few studies that distinguish between side effects of SNRIs and SSRIs because the two classes of antidepressants are so similar in the ways they affect the body. As an SNRI, Effexor shares the increased risk of other birth defects, including heart defects, respiratory distress, anencephaly, craniosynostosis, omphalocele, cleft lip and cleft palate.

Suicidal Thoughts

In 2004, the FDA began warning consumers that, based on many studies, certain antidepressant drugs could increase suicidal thoughts and behaviors in children and young adults. Two years later, the FDA expanded its public health advisory to include young adults as old as 24. Effexor has not been approved by the FDA for use in children, but doctors do prescribe it for older teens. Because of the serious nature of this type of side effect, the FDA requires SSRI and SNRI manufacturers to include black-box warnings about the increased risks of suicidal thoughts and behavior during initial treatment, which the FDA defines as the first one to two months.

Serotonin Syndrome and Discontinuation Syndrome

Patients taking SNRIs are warned to be vigilant about taking any other drugs that could cause an overdose of serotonin in the brain, called serotonin syndrome. Drugs that have been shown to have such interactions include tryptamines, phenethylamines, dextromethorphan, dextrorphan, tramadol, tapentadol, meperidine/pethidine, tritons and MAOIs. This condition is characterized by a sudden onset and can be fatal if it is not caught and treated quickly. Symptoms of serotonin syndrome include high blood pressure, hyperthermia, high body temperature and an increased heart rate that can lead to shock. Another concern for Effexor patients is discontinuation syndrome, which can occur when the medicine is stopped suddenly, the dose is decreased too quickly, or when a dose is missed. Patients with discontinuation syndrome suffer withdrawal symptoms that can include extreme fatigue, severe headaches, stomach cramps, poor coordination and disorientation. To avoid discontinuation syndrome, some doctors switch their patients to SSRIs, which do not have as many withdrawal symptoms, before weaning them off of antidepressants altogether.


Women who took Effexor during pregnancy and had a child who was born with a birth defect or later developed related complications may be entitled to compensation. A qualified product liability attorney can explain their legal options. Two families filed suit in Pennsylvania in August 2012, after their children suffered birth defects after Effexor use by the mothers. One baby was born with craniosynostosis, in which skull formation does not allow room for the brain to grow. The other baby was born with hypoplastic left heart syndrome, a heart defect that requires surgery. In August 2013, federal Effexor birth defect lawsuits were consolidated in the U.S. District Court for the Eastern District of Pennsylvania.