Linaclotide (Linzess)_Dosage, benefits & legal status
Also known as Linzess, Constella, MD-1100, linaclotide acetate
An approved oral peptide for constipation that works in the gut and barely reaches the blood.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Linaclotide (Linzess)?
Plain language first. The technical label stays, but it never stands alone.Overview
It switches on a receptor lining the gut that pulls fluid into the bowel and speeds things along, and almost none reaches the bloodstream. It is approved for IBS with constipation and chronic constipation in adults, and for children with functional constipation from age 2.
Linaclotide is a 14-amino-acid peptide held in shape by three disulfide bonds, related to the gut hormones guanylin and uroguanylin. Ironwood developed it, and it was FDA-approved in 2012 as Linzess (Constella in the EU); AbbVie now markets it with Ironwood.
What it's used for
A prescription capsule for IBS with constipation and chronic constipation. Diarrhoea is the main side effect, and it is dangerous for children under 2.
How does Linaclotide (Linzess) work?
What it does in the body, and where.Linaclotide is a small peptide closely related to the gut's own guanylin and uroguanylin, locked into shape by three disulfide bridges.
- 01GC-C receptorIt binds guanylate cyclase-C on the inner surface of the intestine and raises cGMP inside and outside the lining cells.
- 02Fluid secretionThe extra cGMP drives chloride and bicarbonate out through the CFTR channel. Water follows, softening stool and speeding transit.
- 03Pain signalsReduced activity in pain fibres was shown only in an animal model of gut pain, where extracellular cGMP was the proposed route. The label makes no such claim in people.
- 04Stays in the gutAbsorption is minimal. Blood levels are below the limit of measurement, and about 3 to 5% of a dose is recovered in stool, all as its active metabolite.
A schematic of the compound's mechanism, not a diagnostic image.
What else is it used for?
Each group carries its own evidence level.Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
Adults
FDA-approved- Human trialIBS-C, two trials of about 800 people each: strict 9 of 12 week responders 12% and 13% on 290 mcg against 5% and 3% on placebo.
- Human trialChronic constipation, two trials of about 430 people each: 20% and 15% responders on 145 mcg against 3% and 6% on placebo. A third trial found 13% on 72 mcg against 5%.
Children
FDA-approved- Human trialFunctional constipation, ages 6 to 17, 328 children: spontaneous bowel movements rose by 2.6 a week on 72 mcg against 1.3 on placebo over 12 weeks.
- No dataIBS-C, ages 7 to 17, 53 children on 145 mcg with no placebo arm: 30% met the combined response in the label. The registry posts a 22.6% responder rate for the same group, and the difference has not been explained.
- No dataFunctional constipation, ages 2 to 5, 123 children: the label reports 2.1 against 1.4 bowel movements a week, but the registered primary analysis was not significant (p=0.29).
It is not absorbed into the body in any meaningful amount: blood levels are below the limit of measurement, and no half-life can be calculated. The pain-relief mechanism comes from animal work only. 'Not for children' is out of date: the 2012 label barred under-6s and advised avoiding it to age 17, but it is now contraindicated only under 2 and approved from age 2. 'Take it before the first meal of the day' is the 2012 wording; the current label says before a meal at about the same time each day. MM-419447, the name of its active metabolite, comes from the EU assessment, not the US label. It has no weight-loss indication, despite consumer articles promoting one.
The published record
Papers and trials about Linaclotide (Linzess)
330 papers tagged human · 149 not reviews or lab · 53 clinical trial publications
60 registered trials · 24 with posted results
Furthest stage reached: Approved in the US
Counted from Europe PMC indexing, not read by a person; a human tag can land on reviews, commentary or lab papers; clinical trial publications is the narrower count. 420 papers and 60 trials indexed in detail.
At a glance
Four things to know about Linaclotide (Linzess)
Evidence
FDA-approved
Category
Healing and recovery
Common vial
Varies
Half-life
Not measurable (stays in the gut)
How much, and do you cycle it?
The range, and whether you take breaks.72, 145 or 290 mcg once daily (label), once daily. Continuous, once daily FDA label
Taken once a day for as long as it helps. The EU label advises reviewing treatment if there is no improvement after 4 weeks.
How long does it stay in the body?
The half-life, and where the figure comes from.Not measurable (stays in the gut)FDA label
Linaclotide and its active metabolite are below the limit of quantitation in plasma, so the label gives no half-life, AUC or peak level. It works inside the gut and is broken down there, mainly by losing its final tyrosine.
Source: Linzess prescribing information section 12.3; Constella EPAR public assessment report
You can compare this against the whole library to see where it sits.
What does it cost?
Typical dose and cost, in plain numbers.Linaclotide (Linzess) is not injected
It is taken by mouth (capsule). Adult IBS-C: 290 mcg once daily. Adult chronic idiopathic constipation: 145 mcg, or 72 mcg depending on presentation or tolerability. Children aged 7 and over with IBS-C: 145 mcg. Children aged 2 and over with functional constipation: 72 mcg. Take it on an empty stomach at least 30 minutes before a meal, at about the same time each day. Do not crush or chew; the capsule can be opened onto a teaspoon of apple sauce or into about 30 mL of water. A capsule, so the vial calculator does not apply.
How do you store it?
Before mixing, and after.Dry powder in the freezer or fridge. Once mixed, fridge, and use within about a month.
Unmixed lyophilized Linaclotide (Linzess) keeps for a long time cold. Once you add water the clock starts: most reconstituted vials hold up for roughly 28 to 30 days at fridge temperature. Keep it out of light, and do not freeze it after mixing.
What are the side effects and cautions?
Known cautions and warnings for this compound.Solubility, computed: 21% charged residues, 57% hydrophobic. Base may help.
A first-pass rule from peptide manufacturers' guidance. It does not account for disulfide bridges, salt form or how the powder was dried, and it predicts what should be easy rather than what will happen in your vial.
Who should avoid it
- Children under 2, because of the risk of serious dehydration (boxed warning)
- Known or suspected mechanical blockage of the gut
- Hypersensitivity to linaclotide or any ingredient (EU label)
Stop and get help
- Severe diarrhoea, especially with dizziness, fainting or low blood pressure: reports after approval include hospital admission for dehydration
- Severe or worsening stomach pain, or a swollen, hard abdomen
- A child under 2 who has swallowed a capsule: get medical help
Common effects
- Diarrhoea in 20% of adults on 290 mcg for IBS-C, against 3% on placebo; severe in 2%
- Diarrhoea in 16% on 145 mcg for chronic constipation, against 5% on placebo
- Stomach pain 7%, wind 4% and bloating 2% on 290 mcg
- 9% stopped the IBS-C trials because of side effects, against 3% on placebo
- Much lower rates in children: diarrhoea in 4% of 6 to 17-year-olds with functional constipation
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Linaclotide (Linzess) approved?
And where the numbers on this page come from.Yes. Linaclotide (Linzess) is FDA approved and available on prescription in the United States. It is approved in European Union, but not in the United States.
- Approval statusFDA-approved
- RouteBy mouth (capsule)
- Checked11 October 2026
- Approved outside the USEuropean Union: Authorised in the EU as Constella since 26 November 2012, for moderate to severe IBS with constipation in adults only, at 290 mcg once daily. Current holder AbbVie Deutschland. Also approved in the US.This does not change the United States position above.
- DoseFrom the drug label. The manufacturer tested this range and a regulator reviewed it.
- Vial sizeFrom what vendors typically list; not a recommendation.
- SourcesLinzess prescribing information (DailyMed, revised May 2026)Drugs@FDA, NDA 202811FDA approval letter, S-023 (21 May 2026)Rao S et al., American Journal of Gastroenterology 2012;107:1714-24Lembo AJ et al., New England Journal of Medicine 2011;365:527-36ClinicalTrials.gov, NCT05652205 posted resultsEMA, Constella EPAREMA, Constella public assessment report
What has happened recently
FDA-approved on 30 August 2012 (NDA 202811) for IBS with constipation and chronic idiopathic constipation in adults. A 72 mcg dose for adult chronic constipation followed in January 2017. In August 2021 the boxed warning and contraindication moved from under 6 to under 2 years. Paediatric approvals followed for functional constipation from age 6 (June 2023), IBS-C from age 7 (November 2025) and functional constipation from age 2 (May 2026). In the EU, Constella has been authorised since 26 November 2012 for moderate to severe IBS-C in adults only.
You can compare this against the whole library, or read how to check a seller.
What else is like Linaclotide (Linzess)?
Others in Healing and recovery, side by side.If you're weighing Linaclotide (Linzess), it's worth reading Pentosan Polysulfate (PPS), Redasemtide, and Retinalamin in the same class.
An approved oral peptide for constipation that works in the gut and barely reaches the blood.
- Dose
- 72, 145 or 290 mcg once daily (label)
- How often
- Once daily
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- 0.75 to 1.5 mg/kg daily for 5 days, or weekly (trial doses)
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A Russian retina extract given by injection, from the same tradition as Cortexin.
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- 5 up to 10 mg per day
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Guides for this compound
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
Sources
- Linzess prescribing information (DailyMed, revised May 2026)(2026)Indications, dosing, boxed warning for children under 2, and trial results. Adult IBS-C: 12% and 13% combined responders against 5% and 3%. Diarrhoea 20% against 3%. Plasma levels below the limit of quantitation.
- Drugs@FDA, NDA 202811(2026)Original approval 30 August 2012; 72 mcg dose (2017); boxed warning change to under 2 (2021); paediatric approvals 2023, 2025 and 2026.
- FDA approval letter, S-023 (21 May 2026)(2026)Functional constipation in children aged 2 and older.
- Rao S et al., American Journal of Gastroenterology 2012;107:1714-24(2012)IBS-C phase 3 (Trial 1), 290 mcg against placebo, 12 weeks plus randomised withdrawal.
- Lembo AJ et al., New England Journal of Medicine 2011;365:527-36(2011)Two phase 3 trials in chronic constipation: 145 mcg responders 20% and 15% against 3% and 6% on placebo.
- ClinicalTrials.gov, NCT05652205 posted results(2026)Functional constipation, ages 2 to 5, 72 mcg against placebo. Registered primary analysis: 1.74 against 1.42 bowel movements a week, p=0.29, not significant.
- EMA, Constella EPAR(2026)Authorised 26 November 2012 for moderate to severe IBS-C in adults, 290 mcg once daily. No chronic constipation indication in the EU.
- EMA, Constella public assessment report(2012)One active metabolite, MM-419447. Only 2 of 162 sampled patients had plasma levels just above the 0.2 ng/mL limit.
Beyond these, 480 records are indexed. Browse the records