Linaclotide dosage and evidence
Written by Aaron CuhaReviewed Sep 2026
The short answer
In 839 adults with irritable bowel syndrome and constipation, 60 percent had less belly pain on it, against 49 percent on a dummy capsule. It is a small peptide taken by mouth that works without being absorbed, acting only on the gut lining. It is approved for constipation.
Evidence grade for Linaclotide: Limited. The rule: people have taken it in a published study, but fewer than 100 of them. The sum on this page: 1 completed trial, none stating how many people. A grade counts how much has been done to people, not whether it works.
- People given it
- 0
- Human studies
- 1
- Found nothing
- 0
Dose
Approved medicine. No human dose established for unlabelled uses
Labeled amounts sit on the prescribing information. This page records what trials measured, not a personal dose.
FDA-approved as Linzess for adults with irritable bowel syndrome with constipation, and for adults with long-term constipation that has no known cause. Also approved for children with constipation that has no physical cause. It carries a boxed warning, the FDA's strongest: do not use it in children under two, because of a risk of serious dehydration.
3 effects reported, 2 unwanted, 1 wanted, by people using it, not a trial
In plain English
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
Linaclotide is a small peptide pill for constipation. It works inside the gut and barely gets into your blood. It is an approved prescription drug.
What people take it for
- Constipation that will not shift.
- Belly pain and bloating from irritable bowel syndrome with constipation.
What studies in people showed
In 839 adults with irritable bowel syndrome and constipation, 60 percent on it had less belly pain. On a dummy capsule, 49 percent did. Bowel habits, straining and bloating also got better. Diarrhoea hit 9 percent on the drug and 1 percent on the dummy capsule.
What people report
Reports, not study results
The good
- Less belly pain, better bowel habits and less bloating in the big trial.
The bad
- Diarrhoea, the most common reason people stop.
- Not for children under two, because of the risk of serious dehydration.
Where these come from: From the trial and drug warnings on this page. We have no user reports.
My bottom line
A real drug that works where it lands, in the gut. The lesson for peptide buyers: a peptide you swallow has to reach its target. For most, it never does.
An opinion, not a finding. I am a coach, not a doctor.
What it has been measured to do
Nothing indexed yet
The 1 citation on this page do not report a result for any of the 36 goals indexed here. Most of what sits here is something else: a listing of a planned study, a study of how the body handles the drug, a safety report or a government record. None of those tests whether it works.
Show full evidence
What is Linaclotide?
In 839 adults with irritable bowel syndrome and constipation, 60 percent had less belly pain on it, against 49 percent on a dummy capsule. It is a small peptide taken by mouth that works without being absorbed, acting only on the gut lining. It is approved for constipation.
Linaclotide is the cleverest design on this page, and the reason is surprising. It is a peptide taken by mouth that works exactly because it is not absorbed.
Peptides taken by mouth are usually a problem for drug makers. The gut breaks them down, and almost nothing reaches the blood. Linaclotide turns that into how it works. Its target, a receptor called guanylate cyclase-C, sits on the inner surface of the gut wall. So the drug only has to survive long enough to reach a receptor it is already next to. Very little gets into the blood, and that is on purpose.
It is approved for irritable bowel syndrome with constipation and for long-term constipation with no known cause. In a large trial of 839 adults, run mostly in China, 60 percent on linaclotide had less belly pain, against 49 percent on a dummy capsule. Diarrhoea was the common side effect.
How does Linaclotide work?
Linaclotide is a 14 amino acid peptide that switches on guanylate cyclase-C, a receptor on the inner surface of gut lining cells. It copies two of the body's own gut peptides, guanylin and uroguanylin. Switching on the receptor raises a messenger called cyclic GMP, inside and outside the cells. That opens a chloride channel (CFTR), so chloride and bicarbonate flow into the gut, and sodium and water follow. More fluid in the gut makes things move through faster. The cyclic GMP outside the cells is also thought to calm pain nerves in the gut wall. That is the likely reason it eases belly pain in irritable bowel syndrome, apart from its laxative effect.
What have studies in people found about Linaclotide?
Several final-stage trials back two adult uses and one use in children. The side effects are well known and predictable.
- In 839 adults with irritable bowel syndrome and constipation, run mostly in China, a daily 290 microgram capsule or a dummy capsule: 60 percent on linaclotide had less belly pain, against 49 percent. Bowel habits, straining and bloating improved too. Diarrhoea hit 9 percent on the drug against 1 percent on the dummy capsule.
- Other final-stage trials in irritable bowel syndrome with constipation, in several regions.
- Also approved for long-term constipation with no known cause in adults, and for constipation in children.
- Diarrhoea is the main side effect. It comes straight from how the drug works: it is the intended effect, just too much of it.
- Very little gets into the blood, which limits drug clashes and side effects elsewhere in the body.
- A boxed warning, the FDA's strongest, says not to use it in children under two, because of the risk of serious dehydration.
What this does not tell you: Results in this field are symptom scores, which are personal and swing a lot on a dummy pill. So the drug's effect looks modest next to the dummy pill group. Nothing here is about ageing, longevity or any use outside the approved gut uses. The idea that it calms gut pain through cyclic GMP is a likely explanation, not a proven one.
The state of the research
The design lesson on this page is worth pulling out, because it applies across the site. Getting peptides to work by mouth is usually treated as the hard problem. Huge effort goes into shielding peptides from the gut so they reach the blood. Linaclotide skips all that, because its target is on the inside of the gut. Not being absorbed is a feature.
That matters for anyone weighing peptide products taken by mouth that claim effects around the body. If a peptide is meant to act on muscle, brain or joints, it has to survive digestion and get into the blood, and almost none do. If its target is the gut surface, that hurdle goes away. The question to ask of any peptide taken by mouth is where its receptor is.
The evidence, in charts
Fig. 1a · how many people
1study in people cited, but none says how many people took part
number of people not stated
We do not draw a total, because none of the studies in people on this page gives one. Read the sources below for what each study measured.
We read the number of people from the source lines on this page. Where a line gives no number, we count nothing for it. We do not guess.
Fig. 1b · evidence mix
All 1 source here is a study in people.
- Study in people · done in people1100%
Counted from the list of sources on this page. It counts only what we cite, so there may be more studies out there. A review counts once, however many studies it sums up.
Fig. 2 · evidence over time
Every source here was published in 2018.
Too few different years on this page to draw a timeline. The newest source on file is from 2018, more than five years ago. Research on it may have gone quiet.
Fig. 3 · legal status at a glance
US
Approved
UK
Approved
AU
Approved
CA
Approved
Approved in all four countries shown. This is what the law says, not a verdict on the science. See Legal status below for the full text and any notes.
Fig. 5 · what the molecule is
- Kind of compound
- Peptide
- Molecule weight
- Roughly 1.5 kDa. A 14-amino-acid peptide with three disulfide bonds.
- Half-life
- Stated in words, not a numbersee the exact wording below
- Chain length
- None on file
Half-life as stated on file: Not meaningfully described systemically, because absorption is minimal by design. The peptide and its active metabolite act locally in the gut lumen and are degraded there.
No amino acid sequence is on file for Linaclotide, so none is drawn rather than guessed from a name.
The studies we cite
- Study in people2018Linaclotide in irritable bowel syndrome with constipation: a phase 3 randomized trial in China and other regions
Linaclotide worked for irritable bowel syndrome with constipation, in a large trial run mostly in China. 839 adults were split by chance between a daily 290 microgram capsule and a dummy capsule, and nobody involved knew which. The trial hit every target it set. 60% on linaclotide had less belly pain, against 49% on the dummy capsule. Bowel habits, straining and bloating all improved too. Diarrhoea was the common side effect, in 9% on the drug against 1% on the dummy capsule. Ironwood and AstraZeneca paid for it.
A randomised phase 3 trial of linaclotide in irritable bowel syndrome with constipation. One of the registrational trials supporting approval in this indication.
Where to buy Linaclotide
Linaclotide is an approved medicine. The approved product comes from a pharmacy, with a prescription. The vials below are sold “for research” and are not the approved drug.
1 seller lists Linaclotide in our latest read. They are ranked by trust score, then by archive rating, then by certificate tier, then by the lowest price per milligram. Archive evidence is counted before source-backed. Each path is out of 4, and the two are not added. A higher price does not raise the score. The letter is the certificate chip. 0 of them have a published certificate that names Linaclotide.
Some seller links may pay this site when you buy through them. A payment never changes a seller's tier or rank, and no seller has a say in any page.
| Seller | Trust score | Vial sizes | From, per mg | Certificate for Linaclotide | Seller link |
|---|---|---|---|---|---|
| Boston Molecules | 28 InsufficientSource-backed 1 of 4. Archive evidence 1 of 4.C | 10 mg | $54.0 | None found for Linaclotide | View |
- LC Lab-confirmed: the issuing laboratory echoed this certificate back
- A Current certificate, independent laboratory named, laboratory not yet checked
- B Certificate published, but no laboratory link, older than a year, or the laboratory did not recognise the published lookup
- C No certificate could be read
Every listing and vial size for Linaclotide · How the trust score is counted
Sellers named on the price pages are ranked by certificate tier, then price, and any affiliate income is disclosed there. Naming a seller is not a recommendation to buy or use anything.
Common questions
Has Linaclotide been tested in people?
Yes. 0 people given it across 1 completed trial cited here, 0 of which found nothing. In 839 adults with irritable bowel syndrome and constipation, 60 percent had less belly pain on it, against 49 percent on a dummy capsule. It is a small peptide taken by mouth that works without being absorbed, acting only on the gut lining. It is approved for constipation.
What is the Linaclotide dosage?
Approved medicine. No human dose established for unlabelled uses. Labeled amounts sit on the prescribing information. This page records what trials measured, not a personal dose. FDA-approved as Linzess for adults with irritable bowel syndrome with constipation, and for adults with long-term constipation that has no known cause. Also approved for children with constipation that has no physical cause. It carries a boxed warning, the FDA's strongest: do not use it in children under two, because of a risk of serious dehydration.
Is Linaclotide FDA-approved?
FDA-approved as Linzess for adults with irritable bowel syndrome with constipation, and for adults with long-term constipation that has no known cause. Also approved for children with constipation that has no physical cause. It carries a boxed warning, the FDA's strongest: do not use it in children under two, because of a risk of serious dehydration.
How can an oral peptide work when the gut destroys peptides?
Because its target is in the gut. Linaclotide acts on a receptor on the inner surface of gut cells, so it never needs to get into the blood. Very little is absorbed, on purpose. That is the opposite of the problem most peptides taken by mouth have.
Does that mean other oral peptides work too?
No, and this is the useful lesson. A peptide whose target sits on the gut surface has an easy path. A peptide meant to act on muscle, brain or joints must survive digestion and get into the blood, and very few do. Ask where the receptor is before believing a claim about a peptide taken by mouth.
What is the main side effect?
Diarrhoea. It is the intended effect, just too much of it, not some unrelated harm. It is the most common reason people stop. A boxed warning says not to use it in children under two, because of the risk of serious dehydration.