Vilazodone Diarrhea: What It Is, Why It Happens, and What to Do

When you start taking vilazodone, a prescription antidepressant that works by balancing serotonin in the brain. Also known as Viibryd, it’s used to treat major depressive disorder, but for many people, one of the first things they notice isn’t improved mood—it’s loose stools. Diarrhea from vilazodone isn’t rare. In clinical trials, about 1 in 5 people reported it, especially in the first few weeks. It’s not a sign the drug isn’t working—it’s your body adjusting to higher serotonin levels.

Why does this happen? Serotonin isn’t just in your brain. A big chunk of it lives in your gut, helping control how fast food moves through your intestines. When vilazodone boosts serotonin, it can speed things up too much. This isn’t an infection or food poisoning. It’s a direct side effect, similar to what you might see with other SSRIs like sertraline or fluoxetine. Some people get mild discomfort; others have frequent, watery bowel movements that disrupt sleep or work. The good news? For most, it fades after 2–4 weeks as the body adapts. If it doesn’t, or if you’re losing fluids, feeling dizzy, or losing weight, it’s time to talk to your doctor.

What can you do while waiting for your gut to catch up? Stay hydrated—water, broth, or oral rehydration solutions help more than soda or juice. Avoid spicy foods, caffeine, and artificial sweeteners like sorbitol—they can make diarrhea worse. Probiotics might help some people, though evidence is mixed. Don’t reach for over-the-counter anti-diarrheal meds like loperamide without checking with your provider first. They can mask symptoms and hide something more serious, like serotonin syndrome, a rare but dangerous condition caused by too much serotonin in the body, which can also cause diarrhea along with confusion, rapid heartbeat, or muscle rigidity. If you’re on other meds that affect serotonin—like tramadol, triptans, or even St. John’s wort—you’re at higher risk.

Some people switch to another antidepressant because of this side effect. Others stick with vilazodone and manage it. There’s no one-size-fits-all answer. Your doctor might suggest lowering the dose temporarily, taking it with food (which reduces GI upset), or switching to a different class of antidepressant like bupropion, which rarely causes diarrhea. The key is not to quit cold turkey—sudden stops can cause withdrawal symptoms like dizziness, nausea, or brain zaps.

Below, you’ll find real-world advice from people who’ve been through this, plus comparisons to other antidepressants that are gentler on the gut. You’ll also see what to watch for when side effects cross the line from annoying to dangerous. This isn’t just about diarrhea—it’s about finding a treatment that works for your whole body, not just your mood.