Larazotide

A lab-made "leaky gut" peptide tested for celiac disease. Its big final study was stopped. It is not approved.

FDA statusNot approved

Not approved in the US. Its final trial was stopped in 2022.

Proof it works in people for celiac disease symptomsMixed

Only the lowest dose helped. The final big trial was stopped.

Safety data in peopleLimited

Over 600 people in trials, side effects similar to placebo.

Three separate grades: the law (not approved), proof (mixed), and safety data (decent for a tested drug). Good safety data does not mean it works.

By the Peptide Science Desk Editorial TeamFact-checked against FDA and official sources · Oct 28, 2026Not yet reviewed by a licensed clinician. How we check facts

What is it?

Larazotide is a lab-made chain of 8 building blocks. It was made to block zonulin, a body signal that loosens the "tight junctions." Those are the seals between the cells lining your gut. It is taken by mouth and acts right in the gut.

Why do people use it?

It was built for celiac disease, where gluten hurts the gut even in people trying to avoid it. Online, people call it a "leaky gut" peptide for many other problems. Those uses have not been tested.

Does it really work?

Mixed. Across 4 trials with 626 people, it did not change the gut leak test. Symptoms got a little better in some trials, mostly at the lowest dose. The 342-person trial found the same. In 2022, the company stopped its final big trial. A 2025 study in 12 children with a rare COVID problem looked hopeful but was tiny.

Studies in people

We found 6 studies in people, all in celiac disease except one tiny study in children. None tested "leaky gut" in general.

Study design	People	What they measured	What they found	Year	Journal	PubMed
Randomized, placebo, gluten challenge	21 adults with celiac disease	Safety, gut leak, symptoms	Safe. Fewer gut symptoms than placebo.	2007	Aliment Pharmacol Ther	PMID 17697209
Randomized, placebo, 14-day gluten challenge	86 adults with celiac disease	Gut leak test and symptoms	Gut leak test did not differ. Lower doses limited some symptoms.	2012	Am J Gastroenterol	PMID 22825365
Randomized, placebo, 6-week gluten challenge	184 adults with celiac disease	Gut leak test, symptoms, immune markers	Gut leak test did not differ. The lowest dose limited symptoms.	2013	Aliment Pharmacol Ther	PMID 23163616
Randomized, placebo, 12 weeks	342 adults with celiac disease	Symptoms on a gluten-free diet	Only the lowest dose eased symptoms. Higher doses did not.	2015	Gastroenterology	PMID 25683116
Review of 4 randomized trials	626 adults with celiac disease	Gut leak test and symptoms	No change in the gut leak test. Some symptom help during gluten challenge.	2022	Clin Res Hepatol Gastroenterol	PMID 34339872
Randomized, placebo, phase 2a	12 children with MIS-C after COVID	Safety and recovery	No drug-related side effects. Gut symptoms cleared faster. Very small.	2025	Sci Transl Med	PMID 40737433

Trials listed on ClinicalTrials.gov

ClinicalTrials.gov: final phase 3 trial NCT03569007 (307 people, stopped by the sponsor July 2022)

We read each of these 6 papers on PubMed on October 28, 2026.

Is it safe? Side effects

In trials of more than 600 people, side effects were about the same as placebo.
It is not approved, so there is no FDA label.
Products sold online are not checked by the FDA.

Is it legal in the US?

Larazotide is not FDA-approved. Its last big study was stopped early, so it is not close to approval.

What this means for Larazotide

No company is selling it as a medicine. Anything sold online is an unapproved product. (FDA)
Bringing it into the US for yourself is, in most cases, illegal, the FDA says. (FDA)

Banned in sports? Drug tests

Not named, but may be banned.

Larazotide is not named on WADA's list. But WADA says its list is not complete. It also bans any drug that is not approved for people by any government anywhere (section S0). From Jan 1, 2027, that rule names "peptides" too. Ask USADA before you use it.

Check work, NCAA, and military rules for Larazotide

Talk to your doctor

If you have gut symptoms, ask a doctor to test for celiac disease before cutting gluten. The test works best while you still eat gluten. We never share doses or tell you where to buy. Print our doctor questions sheet.

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Not medical advice. Medical disclaimer.