Effexor or venlafaxine is a prescription medication used to treat depression and anxiety disorders. Despite its effectiveness, Effexor poses a risk for side effects in some patients, including changes to menstruation.
Types of Menstrual Side Effects
Menstrual side effects of Effexor include uterine bleeding not caused by menstruation, lack of menstrual periods, abnormally heavy or long periods and spotting between periods.
Uterine bleeding that is unrelated to menstruation occurs in at least 1 out of every 100 users, according to RxList. Other menstrual side effects are more rare, with some even occurring in less than 1 out of every 1,000 users.
Menstrual side effects of Effexor usually develop within the first few months of treatment. As other side effects of Effexor, menstrual changes may diminish over time as your body becomes accustomed to the drug, according to the Mayo Clinic.
Rarely, the use of Effexor leads to life-threatening hemorrhages of the vagina or uterus. If you develop sudden, heavy menstrual bleeding while taking Effexor, notify your doctor.
When combined with blood thinners such as Warfarin, Effexor causes an increased risk for uncontrollable bleeding. This could make potential vaginal or uterine hemorrhages more severe if they develop.