Antidepressants and weight gain

he exact relationship between antidepressants and weight gain isn't clear, but weight gain is a reported side effect of nearly all antidepressants.

Certain antidepressants are more likely to cause weight gain than are others. For example, tricyclic antidepressants and monoamine oxidase inhibitors (MAOIs) are more likely to be associated with weight gain than are selective serotonin reuptake inhibitors (SSRIs). The exception to this may be long-term use of paroxetine (Paxil) — an SSRI that's more likely to cause weight gain than are other SSRIs.

It's not possible to predict who's most likely to gain weight from taking antidepressants. However, recent research has shown that people who gain weight within about the first week of starting antidepressant treatment are more likely to have significant weight gain from the medication over an extended period of time.

It's important to remember that association is not the same as causation. 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.