Hi Kim:

Prozac is an SSRI and one of the side effects these drugs (in fact, most antidepressants, regardless of class) are weight changes, and that often means weight gain.

However, it's important to remember that this doesn't necessarily mean that they cause weight gain. There are many factors that can work together to contribute to weight gain during antidepressant therapy. Some people lose weight as part of their depression. In turn, an improved appetite associated with improved mood may result in increased weight. Overeating as a result of depression also can cause weight gain. In addition, some medical conditions that mimic depression - such as underactive thyroid (hypothyroidism) - may cause weight gain.

If you gain weight after starting antidepressant treatment, discuss your concerns with your doctor. He or she can determine the likely cause of weight gain. If your antidepressant seems to be the culprit, it may help to adjust the dose or switch medications. In addition, increased exercise, 20-30 minutes 4 times a week of vigorous (running, step aerobics, spinning) will help you keep your weight down, and you will feel much better as well.

Best of luck,

Dr. Diana Walcutt