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Linaclotide (Linzess)

Also known as Linzess.

Approved in the US and the EU for IBS-C and chronic constipation. Safety data past about one year of continuous use are thinner than for older drug classes.

CysCysGluTyrCysCysAsnProAlaCysThrGlyCysTyr
14 amino acids, in order. End caps, bridges and anything attached to the chain are not drawn. Source: PubChem.
Human evidence
Grade A

Large trials

Completed randomized trials
5+

The plus sign marks a floor: the record counts more trials than it lists.

Approved?
US and EU

Approved in the US and the EU

Sport (WADA)
Not named

Not named on WADA's list. That is not clearance.

Checked on .

How we count a trial
Short answer

As of September 2026, linaclotide is an approved medicine in the US and the EU for IBS-C and chronic constipation. Its evidence comes from large Phase 3 trials and more than a decade of use since approval. Those trials stand behind Linzess. If a vial sold as linaclotide reached you outside a pharmacy, they did not test it, and you cannot check its contents by eye.

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What is linaclotide?

Linaclotide is a small, lab-made chain of 14 amino acids designed to mimic guanylin, a natural gut peptide. Ironwood Pharmaceuticals developed it. The FDA approved it in 2012 as Linzess for adults with chronic idiopathic constipation or IBS-C, and in late 2025 added children aged 7 and older with IBS-C.

Does linaclotide work?

For IBS-C and for chronic idiopathic constipation, meaning long-term constipation with no known cause, the FDA reviewed the trials and approved it. In the EU, the EMA approved it for equivalent uses.

What we found. 5+ completed randomized trials counted on the record. 3 study rows listed below, and the first alone stands for two trials. The number shows with a plus sign until every trial is listed.

Studies on the linaclotide record: each study, what it was tested in, its status and what it shows.
Two main Phase 3 trials in chronic constipation (Lembo et al., NEJM 2011)PeopleCompleted. The key trials for FDA approvalSpontaneous bowel movements came more often than with placebo
Main IBS-C trialsPeopleCompleted, randomized. Approval followedBelly pain and bowel symptoms improved against placebo
Trial in children aged 7 to 17 with IBS-CPeopleCompleted. Approved in 2025It supported the November 2025 widening of the label to children
How we count a trial

Is linaclotide safe?

The main concern on the record is diarrhea, which is sometimes severe. The medicine carries a boxed warning against use in children under 2. It rests on a risk of fatal dehydration seen in young animals. Long-term safety data beyond about one year of continuous use are thinner than for decades-old drug classes. All of this describes Linzess. Anything sold as linaclotide outside a pharmacy is a matter for the vial section.

What is in a vial sold as linaclotide?

The trials above were the basis for approving Linzess. We found no sign on this record that linaclotide is sold outside pharmacies. If a vial sold as linaclotide reached you another way, none of those trials tested it, and the checklist lists what to ask the seller.

What don't we know?

  • What safety looks like beyond about one year of continuous use. The data thin out there.
  • What multi-year registries will show in children, the group approved in late 2025.
  • What is in any vial sold as linaclotide outside a pharmacy.

The other side

Linzess comes with a prescription and a doctor's care. Behind it the record puts large Phase 3 trials and more than a decade of use since approval. Where it is thinner is long-term safety data past about one year of continuous use.

What would change this record?

  • Multi-year, real-world safety registries. The record says they would close the gap.
  • The same registries in children, the group approved in late 2025. The record singles that group out.

Change log

  • Record checked. No change logged yet.
Every change on the Table

Three questions to ask next

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More questions about linaclotide

What is linaclotide used for?

IBS-C and chronic idiopathic constipation in adults, and since late 2025 IBS-C in children aged 7 and older. Those are the FDA approvals on the record.

Is linaclotide the same as Linzess?

Linzess is the brand name for linaclotide.

Is linaclotide approved for children?

In the US, yes, for children aged 7 and older with IBS-C, since late 2025. It carries a boxed warning against use in children under 2.

What does linaclotide do in the body?

The record says it acts locally in the gut, where it raises fluid secretion and speeds transit. Very little is absorbed into the bloodstream.

Is linaclotide banned in sport?

It is not named on WADA's list. That is not clearance, and this record holds no sport source. If you compete, check the current List.
Sources

Record checked on . Each source shows the date it was checked.

Other approved drugs

In the same group

All 18 in this group
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