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Gastrointestinal

Linaclotide

Also called Linzess, Constella, MD-1100

Linaclotide is a small peptide pill that works inside the gut to treat chronic constipation and constipation-type irritable bowel syndrome. It is approved for adults and, increasingly, for children.

FDA-approvedApproved by the FDA for at least one use after large human trials.

All printable flashcards

Drawn from its published sequence: 14 residues, one bead each. Dashed arcs are ring bonds.

Overview

Linaclotide is a small peptide pill that works inside the gut to treat chronic constipation and constipation-type irritable bowel syndrome. It is approved for adults and, increasingly, for children.

How it works

Established: linaclotide activates guanylate cyclase-C on the inner lining of the intestine, raising cGMP. This drives chloride and bicarbonate secretion into the gut, drawing in water and speeding transit.

What research shows

  • Adult IBS-C trials (290 mcg): diarrhea 20%, abdominal pain 7% (FDA label).
  • May 2026 expansion to ages 2–5 was based on a 12-week phase 3 placebo-controlled trial (HCPLive).

Doses studied in people

Study or labelDose usedSource
FDA label, adult IBS-C290 mcg orally once daily, at least 30 minutes before the first meal1
FDA label, adult chronic idiopathic constipation145 mcg once daily (72 mcg based on presentation/tolerability)1
FDA label, pediatric IBS-C age 7+145 mcg once daily1
FDA label, pediatric functional constipation age 2+72 mcg once daily1

Label doses shown.

Read this first: these are the amounts given to participants in published studies or written on official prescribing labels, reported for reference. They are not recommendations. Trial doses were chosen for specific patients under medical supervision, and a dose that is safe in one person can be harmful in another.

Safety

  • Boxed warning: serious dehydration risk in children under 2; contraindicated in that age group (deaths in neonatal mice) (label).
  • Contraindicated with known or suspected mechanical bowel obstruction (label).
  • Diarrhea is the most common reaction and can be severe; also abdominal pain, gas and bloating (label).

Report side effects of any drug or product to the FDA through MedWatch. For a possible poisoning in the US, call Poison Control at 1-800-222-1222.

History

Developed by Ironwood Pharmaceuticals and first FDA-approved in 2012 for adult IBS-C and chronic idiopathic constipation. Later approvals added pediatric functional constipation (age 6+), pediatric IBS-C (age 7+, November 2025), and functional constipation down to age 2 (May 2026).

Common questions

Is linaclotide FDA-approved?

Yes, as Linzess, first for adult IBS with constipation and chronic constipation, later adding children 1. In May 2026 the approval was extended to functional constipation from age 2 2.

How does linaclotide work?

It acts on a receptor lining the gut that draws salts and water into the intestine and speeds transit 1.

What doses are on the FDA label?

The label lists 290 mcg daily for adult IBS with constipation and 145 mcg (or 72 mcg) for adult chronic constipation 1. Children's doses are 145 mcg or 72 mcg depending on condition and age 1. These are label figures, not advice.

Is linaclotide safe for young children?

A boxed warning says it must not be used under age 2 because of serious dehydration risk, based on deaths in newborn mice 1.

What are the common side effects?

Diarrhea is the most common and can be severe; it affected 20% of adults in IBS trials 1. Abdominal pain, gas and bloating also occur 1.

Is linaclotide banned in sport?

It is not named on WADA's 2026 Prohibited List 3.

Related compounds

GastrointestinalFDA-approvedFlashcard

Teduglutide

Gattex · Revestive

Teduglutide is a longer-lasting version of GLP-2, a gut hormone that helps the intestine grow and absorb nutrients.

Endocrine (other)FDA-approvedFlashcard

Octreotide

Sandostatin · Sandostatin LAR Depot

Octreotide is a long-acting, man-made version of somatostatin, the body's 'off switch' for many hormones.

Sources

  1. LINZESS (linaclotide) prescribing information (rev. 10/2026) FDA label
  2. FDA approves linaclotide for functional constipation in patients 2 years and older (HCPLive, May 2026) Regulatory
  3. WADA 2026 Prohibited List Regulatory

Last reviewed 2026-10-25 · How we research · Found an error? See our corrections policy.