Side Effects of Effexor, Similar Antidepressants, May Increase Bipolar Disorder Risks: Study

New research suggests that certain types of antidepressants, particularly Effexor, may be linked to an increased risk of mania and bipolar disorder. 

In a study published in the medical journal BMJ Open, researchers from the U.K. report that antidepressants from a class of medications known as selective serotonin reuptake inhibitors (SSRIs), may increase the risk of bipolar disorder and/or mania by up to 35%, with the strongest association seen with the antidepressant Effexor.

Researchers looked at medical records of more than 21,000 adults treated for major depression between 2006 and 2013, who all underwent mental health care in London.

Overall, the rate of mania or bipolar disorder among that group was 10.9 per 1,000 person-years. However, those who had prior antidepressant treatment had a rate of 13.1 to 19.1 per 1,000 person years, even after adjusting for other factors.

SSRIs in particular were linked to a 34% increased risk, while those specifically given Effexor (venlafaxine) had a 35% increased risk. However, the researchers said other factors, such as why the patient was given Effexor over other drugs, could be at play.

“We found an association of venlafaxine with subsequent mania/bipolar disorder,” the researchers concluded. “Although our findings do not demonstrate any causal link between antidepressant therapy and bipolar disorder, the association antidepressant therapy with mania in people being treated for depression reinforces the importance of considering risk factors for mania or hypomania in people who present with an episode of depression. Our findings also highlight an ongoing need to develop better ways to predict future risk of mania in people with no prior history of bipolar disorder who present with an episode of depression.”

Effexor Birth Defect Risks

Concerns about the potential side effects of Effexor are currently the subject of several failure to warn lawsuits filed on behalf of children exposed to the drug before birth, alleging that the medication increases the risk of birth defects when used by pregnant women.

In the federal court system, all Effexor lawsuits are consolidated for pretrial proceedings as part of a multidistrict litigation (MDL), with the cases centralied before U.S. District Judge Cynthia Rufe in the Eastern District of Pennsylvania to reduce duplicative discovery, avoid conflicting pretrial rulings from different judges and to serve the convenience of the parties, witnesses and the courts.