One of the most frustrating things about treating depression is that medication is trial and error. What works wonderfully for one person may do nothing at all (or have adverse effects) for the next person. For example, Prozac helps a lot of people, but it just made me really cranky. Plus there's all the guesswork involved in figuring out the right dose, and the amount of time it takes to switch meds (because you can't just quit one cold turkey and start taking another one).