Linaclotide

Overview

Linaclotide, sold as Linzess in the United States and Constella in some other markets, is a 14-amino-acid peptide taken by mouth. It is FDA-approved for irritable bowel syndrome with constipation, often abbreviated IBS-C, and for chronic idiopathic constipation in adults. It works locally within the gut to ease constipation and, in IBS-C, to reduce associated abdominal pain.

A notable feature of linaclotide is that it is minimally absorbed into the bloodstream. The peptide and its active metabolite act on the surface of the intestinal lining and are largely confined to the digestive tract, which shapes both its effects and its safety profile. This local action distinguishes it from systemically absorbed medications.

Linaclotide is taken as a once-daily oral capsule. It carries an important safety restriction: it is contraindicated in young children because of a serious risk observed in juvenile animal studies. As a result, its approved use is limited to adults, and avoiding pediatric exposure is a central part of how it is prescribed and stored.

How it works

Linaclotide is an agonist of guanylate cyclase-C, a receptor located on the surface of the cells lining the intestine. When linaclotide binds this receptor, it increases the production of cyclic GMP inside and around these cells. This signaling molecule drives the secretion of chloride and bicarbonate into the intestinal lumen, which in turn draws water into the gut.

The increased fluid softens stool and accelerates intestinal transit, relieving constipation. In addition, elevated cyclic GMP is thought to act on pain-sensing nerves in the gut wall, which may help explain the reduction in abdominal pain reported by people with IBS-C. This dual effect on motility and visceral sensation is central to its role in IBS-C.

Because guanylate cyclase-C is concentrated in the intestinal lining and linaclotide is minimally absorbed, the drug's activity is largely restricted to the gut. This local mechanism helps account for why systemic side effects are uncommon while gastrointestinal effects, particularly diarrhea, are the most frequently encountered.

Clinical evidence

Linaclotide's approvals are supported by randomized, placebo-controlled trials in adults with IBS-C and in adults with chronic idiopathic constipation. These studies assessed improvements in bowel movement frequency and stool consistency, and in the IBS-C trials, reductions in abdominal pain, using composite responder endpoints that combined symptom measures over the treatment period.

Across the clinical program, linaclotide demonstrated benefit over placebo for the core symptoms of these conditions, with diarrhea emerging as the most common reason participants discontinued treatment. The trials also informed labeling decisions, including the recognition that some people experience loose stools and that dosing context, such as taking the capsule on an empty stomach, can influence tolerability.

It is fair to frame the evidence as showing meaningful symptom relief for many patients rather than a cure. Individual responses vary, and the studied populations were adults; the drug is not approved or appropriate for children. As with other functional gastrointestinal therapies, the magnitude of benefit differs from person to person, and treatment is often a matter of finding what manages symptoms acceptably.

Dosing & side effects

Linaclotide is taken as a once-daily oral capsule, and guidance generally advises taking it on an empty stomach, typically before the first meal of the day, to improve tolerability. This guide does not provide dose strengths; the appropriate strength and instructions are determined by the prescriber and described in the product labeling. Capsules should be swallowed whole unless a healthcare provider gives alternative instructions.

The most common side effect is diarrhea, which can occasionally be severe and may lead to dehydration or discontinuation. Other reported effects include abdominal pain, bloating, and gas. People who develop severe or persistent diarrhea are advised to contact their healthcare provider.

The most important safety restriction is the contraindication in pediatric patients. Linaclotide must not be used in very young children, in whom it has been associated with a serious risk of dehydration in juvenile animal studies, and it is not recommended in older children and adolescents. Because of this, the medication should be stored safely out of the reach of children, and its approved use is confined to adults.

Frequently asked questions

References

Each source links to its original record — peer-reviewed studies, regulator pages, or reference texts, labelled by type. We summarize findings neutrally; a citation is a reference, not an endorsement, and not a claim that its authors reviewed this page.

1. Rao S, Lembo AJ, Shiff SJ, et al. A 12-week randomized controlled trial of linaclotide in irritable bowel syndrome with constipation. Am J Gastroenterol. 2012. Peer-reviewed study
2. Lembo AJ, Schneier HA, Shiff SJ, et al. Two Randomized Trials of Linaclotide for Chronic Constipation. N Engl J Med. 2011. Peer-reviewed study
3. Di Lorenzo C, Khlevner J, Rodriguez-Araujo G, et al. Efficacy and safety of linaclotide in treating functional constipation in paediatric patients: a randomised, double-blind, placebo-controlled, multicentre, phase 3 trial. Lancet Gastroenterol Hepatol. 2024. Peer-reviewed study
4. Rao SS, Manabe N, Karasawa Y, et al. Comparative profiles of lubiprostone, linaclotide, and elobixibat for chronic constipation: a systematic literature review with meta-analysis and number needed to treat/harm. BMC Gastroenterol. 2024. Peer-reviewed study
5. Kalola UK, Patel P, Chowdhury YS. Linaclotide. 2026. Peer-reviewed study
6. Taclob JA, Kalas MA, McCallum RW. Examining linaclotide for the treatment of chronic idiopathic constipation. Expert Opin Pharmacother. 2024. Peer-reviewed study