BPC-157 and TB-500 half-life, and whose blood was measured

Quick answer

Nobody has ever measured how long BPC-157 or TB-500 stays in a human being. The 15-minute half-life quoted everywhere for BPC-157 means the time for half a dose to disappear from the blood. It was measured as 15.2 minutes in rats and 5.27 minutes in beagle dogs, in a single 2022 study by He and colleagues in Frontiers in Pharmacology that injected into a vein and never tested the shot under the skin that self-directed users take. The 3 to 5 day tissue persistence figure quoted for TB-500 has no published measurement behind it in any species, and that gap between one number that was measured and one that was assumed is why the schedules you find online contradict each other.

The fifteen minutes you have read everywhere was a rat's blood, drawn after an injection into a vein. That figure comes from the one published pharmacokinetic study of BPC-157 that we could locate, meaning one study that tracked the compound's level in blood over time after a dose, and it ran in rats and beagle dogs ¹. For the seven-amino-acid fragment that is sold in vials as TB-500, no half-life has been published in any species at all. Every dosing schedule you have read for these two compounds is inference built on top of those two facts, and this page tells you which number was measured and which was inferred.

This page used to tell readers that certain gene variants made them respond more strongly to BPC-157. We went looking for the study behind that claim and there is not one, in any species. We removed it.

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What has been measured, and in what

The whole published evidence base for how long these two compounds last fits in one table, with the species and the route attached to every number. Only one of the eight rows below involves a human being, and that row is about a different molecule. Read the last column first, because the gap between what was measured and what people do is the point.

Compound	What was measured	Species	Route	Result	Does it match how people use it?
BPC-157	Elimination half-life, the time for blood levels to fall by half	Rat	Injection into a vein	15.2 minutes ¹	No. Almost nobody injects BPC-157 into a vein.
BPC-157	Elimination half-life	Beagle dog	Injection into a vein	5.27 minutes ¹	No, and it is roughly a third of the rat figure in the same study.
BPC-157	Elimination half-life	Beagle dog	Injection into muscle	20.0, 25.5 and 29.3 minutes across three dose levels, with blood levels peaking 6 to 9 minutes after the injection ¹	Closer, but most people inject under the skin rather than into muscle.
BPC-157	Share of the injected dose reaching the bloodstream intact	Rat and beagle dog	Injection into muscle	14 to 19 percent in rats, 45 to 51 percent in beagle dogs ¹	Two separate species ranges. They are often welded into a single "14 to 51 percent" that the paper never reports.
BPC-157	Anything at all after an injection under the skin	None	Injection under the skin	Never tested ¹	This is the route almost every self-directed user takes.
TB-500, meaning Ac-LKKTETQ, 7 amino acids	Detection of the compound and its breakdown products in urine and plasma	Horse	Single 10 mg administration, doping control	Detected by laboratory analysis. No half-life reported ³	The only work in a living animal on the molecule that is in the vial.
TB-500, meaning Ac-LKKTETQ	Half-life or metabolism of the fragment itself	None	Any	Never published for the fragment, in any species, as far as we could locate	The 3 to 5 day tissue persistence figure rests on nothing measured.
Thymosin beta-4, 43 amino acids, a different molecule	Half-life after a drip into a vein	Human	Injection into a vein	Rose as the dose rose, across 42 to 1260 mg, so there is no single figure even for the protein ⁵	Different molecule, different route, given for heart attack, dry eye and leg ulcers rather than a torn tendon.

BPC-157The one people take for injuries that will not heal

TB-500The systemic healer

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The short version, with the sources attached

One study has ever tracked BPC-157 levels in blood over time. It used rats and beagle dogs, tested injection into a vein and into muscle, and had no under-the-skin arm ¹.
Blood levels of BPC-157 did not build up after seven consecutive days of injection into muscle in that study, which contradicts the common claim that these compounds accumulate over weeks ¹.
The TB-500 in commercial vials is Ac-LKKTETQ, seven amino acids ². Thymosin beta-4 is 43 amino acids. Every human figure people quote belongs to the protein, not the fragment.
Rahaman and colleagues report that before their own rat work, no metabolism studies of acetylated thymosin beta-4 had been published ⁴. Their subjects were rats given the 43-amino-acid protein, not the seven-amino-acid fragment in the vial, and for that fragment we could locate no half-life or metabolism study in any species.
How fast a compound leaves the blood and how long its effect lasts are two different measurements. For BPC-157 and TB-500, the second one has not been measured in people either.

What the one BPC-157 study found

He and colleagues published the only pharmacokinetic study of BPC-157 we could locate, in Frontiers in Pharmacology in 2022 ¹. They gave it to rats and to beagle dogs by two routes, into a vein and into muscle, and tracked what happened to it afterwards. After injection into a vein, the elimination half-life was 15.2 minutes in rats and 5.27 minutes in beagle dogs. Every half-life value the study measured came in under 30 minutes.

Injection into muscle looked different, as you would expect from a route where the dose has to seep into the bloodstream rather than arriving in it. In beagle dogs the half-life was 20.0, 25.5 and 29.3 minutes across three dose levels, with blood levels peaking 6 to 9 minutes after the injection ¹. The share of an injected dose that reached the bloodstream intact was 14 to 19 percent in rats and 45 to 51 percent in beagle dogs ¹, roughly a threefold spread between two species given the same compound by the same route.

The study had no subcutaneous arm, meaning it never tested an injection into the fat under the skin. That is the route almost every reader of this page uses, and no number exists for it, in any species. Anyone who quotes you a subcutaneous half-life for BPC-157, or a one to two hour absorption window, is reporting an estimate as though it were a measurement.

What happens to the compound after it leaves the blood

BPC157 was rapidly metabolized into a variety of small peptide fragments in vivo, thus forming single amino acids that entered normal amino acid metabolism and excretion pathways.He L et al., Frontiers in Pharmacology, 2022 (PMID 36588717)

In vivo means inside a living animal. In plain terms, the body takes BPC-157 apart the way it takes apart the protein in a meal, cutting it into short pieces and then into single amino acids, which go into the same pool as the amino acids from dinner. The same study found the compound and its breakdown products leaving in urine and bile ¹.

What the body does to BPC-157 after the injection

Injected, and out of the blood fast

Every half-life the one published study measured came in under 30 minutes: 15.2 in rats and 5.27 in beagle dogs into a vein, 20.0 to 29.3 into muscle [[1]].

Cut into short peptide fragments

The study reports BPC-157 was rapidly metabolized into a variety of small peptide fragments in a living animal, by peptide-cleaving enzymes [[1]].

Broken down to single amino acids

Those fragments become free amino acids that join the same pool as the amino acids from dinner, which is why there is no distinct drug left to eliminate.

Leaves in urine and bile

The same study recovered the compound and its breakdown products leaving by both routes [[1]].

No liver drug-processing enzyme is involved at any point

This is the single most useful thing the study says about drug interactions. A slow-metabolizer result does not lengthen or shorten BPC-157's own half-life. What it can do is raise the blood level of a prescription drug that does travel through those enzymes, which is a co-medication question for a prescriber rather than a peptide-dosing question.

Clearance route as reported in He et al. 2022, in rats and beagle dogs [[1]]. No step of this has been measured in a human.

BPC-157's mechanism, its reported side effects and how to read a vendor's certificate of analysis all live on the BPC-157 monograph, which is the evidence baseline this page works from. A 2025 systematic review of BPC-157 in orthopaedic sports medicine sets out how thin the human evidence still is ⁶.

Two physicians working through what is established and what is extrapolated. A useful counterweight to the confidence of most peptide content.

Why the TB-500 numbers do not belong to TB-500

The TB-500 situation is worse than thin evidence. The figures in circulation were measured on a different molecule.

A fragment is not the protein. TB-500 is seven amino acids; thymosin beta-4 is 43. They are related the way a sentence is related to a paragraph it was taken from.

PeptidesDNA, /peptides/tb-500

That identification is not an opinion. Esposito and colleagues chemically characterised what is inside commercial TB-500 products and found Ac-LKKTETQ, the acetylated 17 to 23 fragment of thymosin beta-4, seven amino acids long ². Thymosin beta-4 is the 43-amino-acid protein your own cells make, and some suppliers sell the full protein under the TB-500 label as well, so two vials with identical labels can hold molecules of different weights. The TB-500 monograph owns that distinction in full.

The fragment in the vial against the protein in the trials

TB-500Seven amino acids, and the twice-weekly loading schedule has no measurement under it.

Ac-LKKTETQ, the molecule sold in vials

Length7 amino acids [[2]]

Measured in a living bodyDetected in horse urine and plasma after a single 10 mg administration, in doping control [[3]]

Human dataNone

Published half-lifeNone we could locate, so nothing anchors a loading schedule

Regulatory statusNot an approved medicine anywhere; sold as a research chemical

Thymosin beta-443 amino acids, and the human number people borrow belongs here.

The natural protein the fragment was cut from

Length43 amino acids

Measured in a living bodyBlood levels tracked in healthy human volunteers given it into a vein [[5]]

Human dataA phase I trial across 42 to 1260 mg, in four groups of ten [[5]]

Published half-lifeRose as the dose rose, so there is no single number [[5]]

Regulatory statusInvestigational, and on the World Anti-Doping Agency prohibited list [[4]]

Human pharmacokinetic figures quoted for TB-500 are taken from the right-hand column and applied to the left-hand one. The two columns are different molecules, given by a different route, for different conditions.

The only work in a living animal on the actual fragment is equine doping control. Ho and colleagues gave horses a single 10 mg administration and showed that TB-500 and its breakdown products could be found in urine and plasma by liquid chromatography and mass spectrometry, a laboratory technique that separates a sample and then weighs the pieces ³. That paper answers the question a racing authority asks, which is whether the compound can be detected. It does not report a half-life, because that was never what it set out to measure.

A short half-life does not mean a short effect

Two separate things get collapsed into the phrase "how long it lasts". Pharmacokinetics is what the body does to the compound: absorbing it, spreading it around, breaking it down, getting rid of it. Pharmacodynamics is what the compound does to the body, and how long that keeps happening. A compound can be gone from the blood in twenty minutes and still have set something in motion that runs for a day, in the same way that turning a key starts an engine that keeps running after you let go of the key.

That principle is standard pharmacology, and for BPC-157 and TB-500 it remains a principle rather than a measurement. Nobody has run a study in people that tracked how long the biological effect of either compound lasts after a dose. A short blood half-life does not rule out a longer effect; the length of that effect is unknown. Any page that tells you BPC-157's effect window is "hours to 24 hours" has put a number on something nobody has measured.

0published measurements of how long either compound stays in a human beingNot for BPC-157, where the figures come from rats and beagle dogs [[1]], and not for the Ac-LKKTETQ fragment sold as TB-500, where we could locate none in any species.

Where the dosing schedules come from

If the persistence numbers were never measured in people, the schedules cannot have been derived from them. What researchers did administer is below, in the species each study used.

Study	Species	Compound	What researchers administered	How long it ran	What it measured
He L et al., 2022 ¹	Rat and beagle dog	BPC-157	Into a vein and into muscle, at several dose levels	Single doses, plus 7 consecutive days of injection into muscle	Blood levels over time, where it went in the body, how it was broken down, how it left
Ho EN et al., 2012 ³	Horse	TB-500 (Ac-LKKTETQ)	A single 10 mg administration	One dose	Whether the compound and its breakdown products could be detected in urine and plasma
Ruff D et al., 2010 ⁵	Human, healthy volunteers	Thymosin beta-4, the full 43-amino-acid protein	Into a vein, 42 to 1260 mg, across four groups of ten	Single and repeated doses	Safety and half-life

No study in that table put either compound under the skin of a person with a tendon injury, which is the use both compounds are overwhelmingly sold for. The community schedules came from practice and from vendor literature, then acquired a pharmacokinetic justification after the fact. Those schedules may or may not match what a human study would show; nobody can say, because the study has not been done. We are not recommending any schedule, and what belongs near you is a question for a clinician who knows your history and your medication list.

Our own BPC-157 dosage guide puts the same point in one line: "There is no human dose-finding study." If it is a specific injury that brought you here, the condition pages cover what else is used for it and how the evidence compares: tendonitis and injury recovery.

Why two people on the same protocol get different timelines

This is the question underneath most half-life searches, and the answer is mostly not genetic. Ranked by how much they plausibly move a timeline, with the largest first:

The dose. A roughly threefold difference in how much reaches the bloodstream showed up between two species given the same injection into muscle, 14 to 19 percent in rats against 45 to 51 percent in beagle dogs ¹, and dose differences between two people are usually larger than that.
The route. Into a vein, into muscle, under the skin and swallowed are four different exposure patterns, and only two of them have ever been measured for BPC-157 ¹.
The injection site and technique. Depth, angle, whether the needle landed in fat or muscle, and how well the vial was mixed all change how much compound enters circulation and how fast.
The injury and its stage. A fresh tendon strain and a five-year-old one are different biological problems, and the injury recovery page covers how stage changes what is worth trying.
Elapsed time. People compare week three to somebody else's week nine and call it a difference in response.
What is in the vial. Purity, actual milligram content, and whether the label matches the molecule are unregulated and vary between suppliers.
Genetics, last, and by a distance. Nobody has ever measured it as a factor here at all.

Where genetics comes in, and where it does not

No trial in any species has sorted responders from non-responders to BPC-157 or TB-500 by genotype. A 2025 systematic review of BPC-157 in orthopaedic sports medicine found no such data ⁶, and a search of the published literature returns nothing for either compound tested against a genetic variant. Any claim that a particular variant makes you respond more strongly to BPC-157 at the same dose is invented. That includes the versions of this claim that used to appear on this page, which we have removed.

There is one genetic point here that a reader can act on, and it is about the other things in your medicine cabinet. As the clearance route above shows, neither compound is handled by the liver's drug-processing enzymes, so a slow-metabolizer result does not lengthen or shorten either peptide's own half-life. What it can do is raise the blood level of a prescription drug that does travel through those enzymes. The CYP3A4*22 variant, for instance, is associated with less of that enzyme being made and lower clearance of drugs routed through it ⁷, which is a co-medication question to take to a prescriber, not a peptide-dosing question.

What is in the vial matters more than the half-life

For a self-directed user, the largest uncontrolled variable is whether the vial holds what the label says, at the stated milligram amount, without contamination. Neither compound is made under pharmaceutical manufacturing rules, nobody is checking, and in the TB-500 case the label itself is ambiguous between a seven-amino-acid fragment and a 43-amino-acid protein ². Mixing errors compound that: the same vial reconstituted with different volumes of water yields different concentrations per unit on the syringe, which is covered in how to reconstitute peptides.

Heads upContamination is the practical hazard

An unverified vial carries more risk than anything either molecule does. An injection site that gets redder, hotter, more swollen or more painful over 24 hours rather than settling, or any fever, chills, spreading redness or discharge, needs same-day medical attention rather than a forum post: those are signs of infection, and an unverified vial is one plausible route. Sterile technique is its own skill set, covered in peptide injection hygiene. Separately, much of what both compounds are described as doing involves growing new blood vessels, which is also how tumours establish a supply, and that description comes from animal and cell work. Nothing shows either one promotes cancer and nothing rules it out, because no carcinogenicity study has been done for either, and that absence is the reason a cancer history is a conversation for an oncologist rather than a decision made alone. Third-party testing and vendor documentation are compared at /compare, where PeptidesDNA earns a commission on some of the vendor links. That page is a record of what each vendor publishes rather than a recommendation to buy or to use either compound, neither of which is approved for human use in the United States, and a "research use only" label on a vial is a marketing convention rather than a legal shield.

Legal status in the United States in 2026

BPC-157 is not an approved medicine anywhere. The FDA placed it in Category 2 for bulk compounding in 2023, which barred compounding pharmacies from using it, and removed it from Category 2 in April 2026 after the nominations behind it were withdrawn ¹⁰. Removal is not permission. It was never added to Category 1, which is the only list a compounding pharmacy may actually draw from, so no US pharmacy can legally compound BPC-157 today, and clinics that resumed on the strength of the April headlines are in a gray zone. On 23 July 2026 an FDA advisory panel voted narrowly in favour of allowing compounding of certain unapproved peptides ⁸; a positive vote is the first gate rather than the last, and the rulemaking that would follow one is expected to take more than a year. Neither compound is legal to sell for human use in the United States in the meantime, and nothing on this page should be read as saying otherwise. The full picture is at are peptides legal in the US in 2026.

Anti-doping status is where a short half-life misleads people most. BPC-157 is prohibited at all times under the World Anti-Doping Agency's non-approved substances category, not only in competition, so there is no permitted dose and no washout window to calculate ⁹. Thymosin beta-4 is on the prohibited list by name ⁴, which is why the only laboratory work on the fragment comes from doping control rather than from clinical pharmacology. A detection window is set by what an assay can find, including breakdown products, rather than by how fast blood levels fall, so if you compete under anti-doping rules, assume TB-500 is testable: the assays exist and were published in 2012 ³.

Link · Frontiers in Pharmacology, 2022Pharmacokinetics, distribution, metabolism, and excretion of body-protective compound 157 in rats and dogsThe only published pharmacokinetic study of BPC-157. Open it and read the route column before you accept any half-life figure quoted for this compound.pubmed.ncbi.nlm.nih.gov

The BPC-157 number came from a rat's vein. The TB-500 number was never taken. That is why two protocols you find online can both cite pharmacokinetics and still contradict each other. If this is your first peptide, start at peptides for beginners and come back.

Genetics does not decide how long these compounds last, and no study has sorted responders from non-responders to either one. Where your DNA does carry information is the prescription drugs you take alongside them. Upload the raw DNA data you already have and get all 39 peptides ranked against your own 144-marker panel, reviewed by a human before it reaches you, as education rather than a recommendation to take anything.

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The distinctions

Clearance is the wrong frame for scheduling these two
How fast a compound leaves the blood and how long its effect lasts are different measurements, and for BPC-157 and TB-500 only the first has been measured, only in animals. The daily and twice-weekly schedules predate the pharmacokinetics now cited for them: they came from practice and vendor literature first, and acquired the justification afterwards.

Sources10

This article is for informational and educational purposes only. It is not medical advice and does not diagnose, treat, cure, or prevent any disease. Consult a qualified healthcare professional before starting any peptide protocol. Individual results vary. Some outbound links are affiliate links, at no extra cost to you.

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The one people take for injuries that will not heal

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Frequently asked questions

What is the half-life of BPC-157?

In the only published pharmacokinetic study of BPC-157, the elimination half-life after injection into a vein was 15.2 minutes in rats and 5.27 minutes in beagle dogs, and after injection into muscle in beagle dogs it was 20.0, 25.5 and 29.3 minutes across three dose levels, with blood levels peaking 6 to 9 minutes after the injection [[1]]. No human half-life for BPC-157 has ever been measured, and that study had no subcutaneous arm, so there is no published figure for the injection under the skin that most people use.

How long does TB-500 stay in your system?

Nobody has published a measurement. TB-500 sold in vials is Ac-LKKTETQ, a seven-amino-acid fragment [[2]], and we could locate no half-life or metabolism study of that fragment in any species. The nearest published work is about the full 43-amino-acid protein: Rahaman and colleagues report that before their own rat experiments, no metabolism studies of acetylated thymosin beta-4 had been published [[4]]. The only work in a living animal on the fragment itself is equine doping control, where the compound and its breakdown products were detected in horse urine and plasma after a single 10 mg administration, without a half-life being reported [[3]]. The widely quoted 3 to 5 day tissue persistence figure is vendor material rather than a measurement.

Why does BPC-157 keep working after it clears the bloodstream?

This is a general pharmacological principle rather than a measured fact about BPC-157. A compound can be cleared from blood quickly and still have triggered cellular activity that continues afterwards, which is why a short half-life does not by itself imply a short effect. For BPC-157 specifically, no study has measured how long the biological effect lasts after a dose in a human, so any specific effect window you see quoted, such as 24 hours, is an estimate presented as a number.

Do CYP3A4 or CYP2D6 variants affect how BPC-157 is metabolized?

No. BPC-157 is broken into small fragments and then single amino acids that enter normal amino acid metabolism, and it leaves in urine and bile [[1]], so the liver's drug-processing enzymes are not involved in clearing it. CYP variants matter for a different reason: if you take prescription drugs that do travel through those enzymes, reduced-function variants such as CYP3A4*22 are associated with lower clearance of those drugs [[7]], which is a conversation for your prescriber. Consumer DNA arrays cannot reliably call CYP3A4 or CYP2D6 in any case.