SSRI Weight Gain: Why It Happens and What You Can Do

When you start taking an SSRI, a class of antidepressants that increase serotonin levels in the brain to improve mood. Also known as selective serotonin reuptake inhibitors, these drugs are among the most prescribed treatments for depression and anxiety. But for many, a surprising side effect shows up months in: weight gain. It’s not in the ads. It’s not always discussed by doctors. Yet studies show up to 25% of people on SSRIs gain 7% or more of their body weight over a year.

This isn’t about willpower. It’s biology. SSRIs like Citalopram, the active ingredient in Celexa, commonly linked to increased appetite and slowed metabolism and Duloxetine, found in Cymbalta, which affects both serotonin and norepinephrine and often leads to cravings for carbs change how your brain regulates hunger and energy use. Serotonin isn’t just about mood—it’s tied to your appetite signals. When it’s flooded, your brain starts sending mixed messages: eat more, burn less. Some people feel hungrier. Others get cravings for sugary or starchy foods. A few notice their body just holds onto weight, no matter what they do.

Not all SSRIs act the same. Some, like fluoxetine, are less likely to cause weight gain. Others, like paroxetine, have a stronger link. And it’s not always immediate—many people don’t notice changes until after six months. That’s why it’s easy to miss. You feel better emotionally, so you don’t connect the scale to the pill. But if you’re gaining weight and you’re on an SSRI, it’s worth looking at the connection. You don’t have to stop your medication. You can adjust your diet, add movement that fits your energy, or talk to your doctor about switching to a different option. Below, you’ll find real comparisons of antidepressants, how they affect weight, and what alternatives exist that might work better for your body.