Managing Diarrhea on Antidepressants

When you start taking antidepressants, medications used to treat depression, anxiety, and other mood disorders. Also known as antidepressive drugs, they help balance brain chemicals—but they don’t always play nice with your gut. Diarrhea is one of the most common side effects, especially in the first few weeks. It’s not just annoying—it can make you feel worse than the depression you’re trying to treat. The truth? About 1 in 3 people on SSRIs like sertraline or fluoxetine report loose stools, and many stop their meds because of it.

Why does this happen? Antidepressants, especially SSRIs and SNRIs, boost serotonin—not just in your brain, but also in your gut. Your intestines have more serotonin receptors than your brain does. Too much serotonin there means faster contractions, less water absorption, and boom: diarrhea. It’s not an allergy. It’s not food poisoning. It’s a direct chemical effect. Some people’s guts adjust after a few weeks. Others don’t. And if you’re on multiple meds, or have IBS to begin with, the odds go up. You might also be mixing it with something else—like a supplement, antibiotic, or even coffee—that’s making it worse. Watch for signs of serotonin syndrome, a rare but dangerous buildup of serotonin that can cause fever, confusion, rapid heartbeat, and severe diarrhea. If your diarrhea comes with shaking, high fever, or confusion, get help immediately.

There are practical ways to manage this without quitting your antidepressant. Start with simple fixes: eat smaller meals, avoid spicy or fatty foods, and cut back on caffeine and artificial sweeteners like sorbitol. Probiotics can help some people—look for strains like Lactobacillus rhamnosus GG. If that doesn’t work, your doctor might suggest switching to an antidepressant with lower gut impact, like bupropion or mirtazapine. Sometimes, a low dose of loperamide (Imodium) for short-term relief is fine, but don’t use it long-term without talking to your provider. The key is not to suffer in silence. Diarrhea from antidepressants is common, treatable, and rarely a reason to give up on treatment. Below, you’ll find real-world advice from people who’ve been there, plus guides on how to spot when it’s just a side effect—and when it’s something you need to act on.