SIDE EFFECTS: The most commonly noted side effects associated with nefazodone are nausea, dizziness, insomnia, agitation, tiredness, dry mouth, constipation, lightheadedness, blurred vision, and confusion. Rarely, nefazodone is associated with priapism or prolonged penile erection. Compared with trazodone, nefazodone has a lesser risk of priapism (prolonged penile erection). Although the erection usually subsides eventually, occasionally blood clots form within the penis and cause serious damage to the penis. Nefazodone rarely may cause liver failure that may result in liver transplantation.