By affecting certain brain chemicals, Effexor^® (venlafaxine hydrochloride) can help treat depression in adults. However, Effexor is not suitable for everyone. Before taking Effexor, make sure to talk to your healthcare provider about any medical conditions you have and any medications you are taking (including vitamins and herbal supplements). Although most people tolerate Effexor well, there are some potential side effects of the medication, such as nausea, drowsiness, and headaches.