With the use of the newer antidepressants beyond the traditional tricy
clics and monoamine oxidase inhibitors, newer options in headache prop
hylaxis are provided as well as the potential for undesirable and even
potentially life-threatening interactions between medications. In thi
s article, four patient reports of a specific interaction-the serotoni
n syndrome-are presented. These events resulted from transitioning hea
dache patients from an older antidepressant (phenelzine) to a newer an
tidepressant (venlafaxine).