Irritable bowel syndrome with constipation (IBS-C) can include hard or infrequent stools plus belly pain, bloating, and a feeling of incomplete emptying. When basics like food changes, stress support, and over-the-counter options are not enough, clinicians may consider prescription medicines that increase fluid in the gut to help stool move more easily. Three common options are linaclotide, plecanatide, and lubiprostone.
How these medicines work (and why they’re called “secretagogues”)
All three medicines are often grouped as secretagogues for IBS-C, meaning they help the intestines “secrete” more fluid into the stool. More fluid can make stool softer and easier to pass, and may also help bowel movement frequency.
Two of the medications, linaclotide (Linzess) and plecanatide (Trulance), are guanylate cyclase-C (GC-C) agonists. They work on receptors on the lining of the intestine to increase fluid secretion and support movement through the colon. In IBS-C studies, these GC-C medicines have also been linked with improvements in overall IBS-C symptoms, including abdominal pain for some people (pain relief is thought to relate to effects on gut nerve signaling). Lubiprostone (Amitiza) works differently. It is a chloride channel activator, which also increases intestinal fluid and helps stool pass.
In the American College of Gastroenterology (ACG) guideline on IBS, the ACG recommends both chloride channel activators (like lubiprostone) and GC-C agonists (linaclotide and plecanatide) as effective options for treating overall IBS-C symptoms. The guideline also notes the U.S. Food and Drug Administration (FDA) doses used for IBS-C: linaclotide 290 mcg daily, plecanatide 3 mg daily, and lubiprostone 8 mcg twice daily (approved for adult women). [1]
Comparing benefits, side effects, and practical differences
For many patients, the “best” constipation prescription for IBS-C is the one that balances symptom goals with side effects and daily routine.
Linaclotide (linaclotide IBS-C) is taken once daily on an empty stomach, at least 30 minutes before a meal. The most common side effect is diarrhea, and it can be severe in some cases. In adult IBS-C trials, diarrhea was reported in about 20% of people taking linaclotide (compared with 3% on placebo). The label also includes a boxed warning about serious dehydration risk in children under 2 years, and it lists suspected bowel blockage (mechanical gastrointestinal obstruction) as a reason the medication should not be used. [2]
Plecanatide (plecanatide IBS-C) is also taken once daily, and can be taken with or without food. Diarrhea is the most common side effect, and severe diarrhea is possible. In IBS-C trials, diarrhea was reported in about 4.3% of people taking plecanatide (compared with 1% on placebo). The label has a boxed warning about serious dehydration risk in children, and it is contraindicated under age 6, with use avoided under age 18. [3]
Lubiprostone (lubiprostone IBS-C) is taken twice daily with food and water, and it is FDA-approved for IBS-C in women age 18 and older. A key practical difference is the side effect pattern: nausea is common (reported around 8% at the IBS-C dose), and diarrhea can also occur (around 7%). Taking it with food may reduce nausea. [4]
Because IBS-C symptoms can change week to week, tracking stool frequency, stool form, belly pain, bloating, and side effects can support clearer conversations with a clinician about whether a medication is helping. Track constipation response in Aidy to spot patterns over time.