Diarrhea from Lexapro typically fades within the first one to two weeks as your body adjusts to the medication. About 8% of people taking Lexapro experience diarrhea in clinical trials, compared to 5-6% on placebo, meaning only a small portion of cases are truly caused by the drug itself. For most people, this is a temporary startup side effect that resolves on its own without any change in treatment.
Why Lexapro Causes Diarrhea
Most of your body’s serotonin is actually produced in the gut, not the brain. Lexapro works by increasing serotonin activity, and that shift affects the digestive system along with everything else. Higher serotonin levels in the intestines speed up gut motility, which is what causes loose stools or diarrhea in the early days of treatment. This is the same reason nausea is another common startup side effect.
Your digestive system gradually adapts to the new serotonin levels. That adjustment period is why diarrhea tends to be worst in the first few days and then tapers off. If you’re still experiencing it after two to three weeks, it’s worth flagging to your prescriber, because persistent diarrhea at that point is less likely to resolve on its own.
Dose Makes a Big Difference
FDA clinical trial data shows a clear relationship between dose and diarrhea. At 10 mg per day (the standard starting dose), only 6% of participants reported diarrhea, barely above the 5% rate in the placebo group. At 20 mg per day, that number jumped to 14%, roughly double. This means diarrhea is far more common at higher doses, and if you recently increased your dose, the symptom may restart temporarily before settling again.
Many prescribers start patients at 5 mg for the first week specifically to minimize gut side effects. If you jumped straight to 10 mg or higher and are struggling, your doctor may suggest temporarily stepping back to a lower dose and building up more gradually.
What You Can Do in the Meantime
Taking Lexapro with food can help buffer its impact on your stomach and intestines. It doesn’t matter whether you take it in the morning or evening, so if diarrhea is disrupting your day, try shifting the dose to a time that’s less inconvenient. Staying well hydrated matters more than usual, since diarrhea depletes both water and electrolytes.
Avoiding caffeine, alcohol, high-fat foods, and dairy during the adjustment period can reduce the load on your digestive system while it’s already irritated. Bland, easy-to-digest foods like rice, bananas, toast, and broth are standard recommendations for any short-term diarrhea.
Over-the-counter anti-diarrheal medications containing loperamide (like Imodium) are sometimes used for relief, but there’s an important caution: both loperamide and Lexapro can affect heart rhythm, and using excessive doses of loperamide alongside Lexapro increases the risk of cardiac complications. If you use loperamide, stick strictly to the label directions and don’t exceed the recommended dose or duration.
When Diarrhea Signals Something More Serious
Simple diarrhea from Lexapro is uncomfortable but not dangerous. However, diarrhea can also be one symptom of serotonin syndrome, a rare but serious reaction to medications that raise serotonin levels. The key difference is that serotonin syndrome never shows up as diarrhea alone. It comes with a cluster of other symptoms: agitation, confusion, rapid heartbeat, fever, heavy sweating, muscle twitching or stiffness, tremor, and poor coordination. You’d need at least three of these symptoms together for serotonin syndrome to be a concern.
The risk is highest when Lexapro is combined with other medications that also increase serotonin, such as certain migraine drugs, pain medications, or other antidepressants. If your diarrhea is accompanied by any combination of the symptoms above, especially fever, muscle rigidity, or mental confusion, that requires immediate medical attention.
If It Doesn’t Go Away
For a small number of people, diarrhea persists beyond the adjustment window and becomes a lasting side effect rather than a temporary one. If you’re still dealing with it after three to four weeks at a stable dose, your prescriber has several options: lowering the dose, switching to a different medication in the same class, or trying a different class of antidepressant altogether. Some medications in this category are more likely to cause constipation than diarrhea, so a switch can sometimes solve the problem entirely.
It’s also worth ruling out other causes. Diarrhea that started around the same time as a new medication feels like an obvious connection, but infections, dietary changes, stress, and other conditions can overlap with the timing. If the diarrhea is severe, bloody, or accompanied by significant abdominal pain, those features point away from a typical medication side effect and toward something that needs its own evaluation.