What are BPC-157 and TB-500?

What they are

BPC-157 is a lab-made peptide: a short chain of amino acids, the building blocks of proteins. It has 15 amino acids, and its letters stand for body protection compound. A University of Zagreb team in Croatia described it in 1993 as a fragment of a protein isolated from human stomach juice.^1,2

Most published BPC-157 studies come from the Zagreb team, a 2026 review notes. It called the lack of repeat studies by independent laboratories a serious limitation.³

Thymosin beta-4 is a small protein of 43 amino acids, first isolated from calf thymus, a gland where immune cells mature. Cells throughout the body make it.^4,5

TB-500 is a common name, not an official drug name. The FDA describes it as a lab-made fragment of thymosin beta-4: its 17th to 23rd amino acids, with a small chemical cap (an acetyl group) on one end. It appeared in 2011 as a veterinary product, and in 2012 a Belgian anti-doping laboratory identified the fragment in a product called TB-500. Several websites treat TB-500 and thymosin beta-4 as interchangeable, but the FDA says they differ.^4,6

How they work

How BPC-157 works is unknown; the FDA’s 2026 review says its molecular targets have not been identified. In a 2017 study in rats and human cells, it increased the growth of new blood vessels (angiogenesis).^2,7

A 1995 lab study reported that human stomach juice does not break BPC-157 down. In rats and dogs, half of it leaves the blood within minutes. The FDA found no data on how much reaches the blood in people who swallow, spray or inject it; in two enema studies, it was not detected in blood.²

Thymosin beta-4 binds actin, the protein that forms each cell’s internal scaffolding, and holds single actin molecules in reserve, which helps cells move. TB-500 contains the stretch that binds actin, but whether it acts like the whole protein is unknown. The FDA cautions that results from the uncapped fragment may not apply to TB-500.⁴

How they are taken

The FDA’s review found BPC-157 sold as injections under the skin (subcutaneous injections), capsules, tablets, and mouth and nasal sprays, some combined with TB-500. Some capsules and tablets are sold as dietary supplements.²

TB-500 is sold online as a powder for injection and in nasal sprays, and several sites the FDA found label it for research use only. A withdrawn request to the FDA to list it for pharmacy compounding proposed injection under the skin or into a muscle.^2,4,8

Animal studies

A 2025 systematic review, which gathers every eligible study under rules set in advance, covered BPC-157 in sports medicine: 36 studies, 35 in animals or cells. In those, the reviewers reported, it improved recovery from muscle, tendon, ligament and bone injuries.⁹

In a 2024 lab study cited by the FDA, TB-500 did not speed the closing of a scratch across a layer of cells. In a 2026 study of 32 rats with repaired Achilles tendons, those given TB-500 for four weeks had stronger, better-organized tendons than untreated rats. With BPC-157, tendons also scored better, but the differences could have been chance. The two together did no better than either alone.^4,10

What the research in people shows

The FDA’s review found five small, short studies of BPC-157 in people, two known only from conference abstracts, brief summaries presented at scientific meetings. A 2026 systematic review judged the other three, with 30 participants in all, to be of poor quality and the evidence very uncertain. Its authors said BPC-157 should not be used outside high-quality clinical trials.^2,11

The 2021, 2024 and 2025 studies share a lead author, were run at private clinics in Florida and appeared in the same journal. The only controlled studies are the 2002 to 2005 abstracts, from when BPC-157 was tested as an enema under the code name PL-14736.^2,12,13,14

Four more BPC-157 studies are registered on ClinicalTrials.gov, the US trial registry, and none has posted results. The largest is a randomized trial of injections or placebo, planned for 120 people with hamstring strains, begun in China in February 2026.^16,17,18,19

The only published report of TB-500 given to people is the 2026 dental cases above; the FDA found no clinical studies. A placebo-controlled safety trial, planned for 80 adults with stable cardiovascular disease, began in China in February 2026.^4,15,20

Side effects and risks

No serious side effects were reported in the five BPC-157 studies the FDA reviewed. But the studies were small, the longest controlled one lasted two weeks, and most did not describe how side effects were checked.²

Through December 4, 2025, the FDA’s side effect database held three reports involving injected BPC-157: injection-site redness and swelling, shortness of breath needing an emergency visit, and skin and gum darkening. The darkening returned when the person restarted the product, a blend with TB-500 labeled for research only. The FDA could not tie any report to BPC-157 itself. Pharmacies compounding for individual patients generally do not report side effects to the FDA, it notes.²

For both peptides, the FDA raises the risk of an immune reaction (immunogenicity): the body may make antibodies against an injected peptide, especially one with clumps (aggregates) or impurities. Injections under the skin and nasal sprays carry more of this risk than swallowed products. Reactions range from none to life-threatening; antibodies could block the body’s own version of the peptide. No study has tested either peptide for this, the FDA found.^2,4

The test reports offered with raw BPC-157 and TB-500 (certificates of analysis) usually showed little beyond purity, the FDA found, without tests for specific impurities or bacterial toxins (endotoxins). It calls endotoxin testing critical for an injected ingredient. It also found different salts and related molecules sold under each name, so a patient may get a different substance than prescribed.^2,4

A French horse-racing laboratory’s 2023 report analyzed three products sold online, including one named TB500. It called all three misbranded, meaning wrongly labeled.³⁶

Formal animal safety studies of BPC-157 used only injections into muscle, none by mouth, nasal spray or injection under the skin. In 28-day studies, it altered blood clotting tests in rats and dogs and raised liver-related blood tests, which the FDA called clinically relevant safety signals. It did not cause genetic mutations in standard tests, and the FDA found no long-term animal studies of cancer risk.²

One study injected BPC-157 into the muscle of pregnant rats and found no birth defects, but it did not look at fertility or development after birth. The FDA found no reproductive studies of TB-500.^2,4

Because BPC-157 increased blood vessel growth in animal and cell studies, a 2025 review raised a theoretical concern. Tumors need new blood vessels, so the reviewers said it may not suit anyone with an undetected cancer.^7,37

The FDA found no animal safety studies of TB-500. In a 2003 mouse study, melanoma (skin cancer) cells engineered to make extra thymosin beta-4 formed larger tumors under the skin and more tumors in the lungs. That study looked at the protein made inside tumor cells, not at taking TB-500.^4,38

FDA status

None of the three is approved or licensed by the FDA for any use, and the FDA found no BPC-157 product approved anywhere. No thymosin beta-4 product appears in the FDA’s database of licensed biological products, the category that includes vaccines, blood products and proteins.^2,4,39,48

Compounding is when a pharmacy or physician prepares a medicine for one patient. Under federal law (section 503A), a pharmacy’s raw drug ingredients must have an official quality standard (a USP monograph), be part of an FDA-approved drug or be on the 503A bulks list. The FDA says neither peptide has a monograph or is part of an approved drug, and neither is on the list.^2,4,40,41

Pharmacies have compounded BPC-157: side effect reports and the three Florida studies in the FDA’s review involved compounded products. The FDA could not tell how widely it is compounded now, and found no pharmacy marketing compounded TB-500. Outsourcing facilities, compounders registered with the FDA under section 503B, reported making neither.^2,4,13

The FDA has named both in warning letters. In 2019 it told a compounding pharmacy its drugs made with BPC-157 acetate did not qualify for the compounding exemptions. In 2023 it called an online seller’s injectable and nasal BPC-157 and TB-500 unapproved new drugs, despite labels saying they were for research only.^8,43

The FDA once placed both in Category 2, nominated ingredients that “may present significant safety risks”, until their nominations were withdrawn. Neither is in Category 1, the group the FDA’s interim policy does not act against.^40,44,45

FDA staff reviewed both for a July 2026 meeting of the agency’s Pharmacy Compounding Advisory Committee, a panel of outside experts. Assessing BPC-157 for ulcerative colitis and TB-500 for wound healing, they advised against adding either to the list in reviews dated May 2026. They cited poor chemical characterization and existing FDA-approved treatments for both. BPC-157 also had too little information on safety and benefit; TB-500 had no compounding history, no data from people and a risk of immune reactions.^2,4,46

The Department of Health and Human Services (HHS), the FDA’s parent department, reports the committee voted in favor of listing both on July 23, 2026, against the advice of FDA staff. As of November 14, 2026, the FDA had posted no minutes or vote counts on its meeting page, and the 503A bulks list was unchanged.^41,46,47,52

On October 30, 2026, HHS published notice of a draft policy that names six peptides, BPC-157 and TB-500 among them. HHS says it does not intend to take enforcement action against state-licensed pharmacies and physicians that compound their acetate forms for individual patients under its conditions. It covers BPC-157 only as injections under the skin or into a muscle or as forms taken by mouth or put on the skin, and TB-500 only as those injections. It does not cover outsourcing facilities or full-length thymosin beta-4.^42,52

Its conditions include one active ingredient per product, so no BPC-157 and TB-500 blends, and records showing that people absorb enough of any form taken by mouth. The draft is not binding, is not an FDA approval and adds neither peptide to the 503A bulks list. The journal’s article on which peptides a pharmacy can compound explains the rest of the draft.^42,52

Full-length thymosin beta-4, at 43 amino acids, counts as a protein under federal rules, and so as a biological product. The FDA says pharmacies cannot compound biological products under the federal compounding exemptions.^48,49

Rules in sport

The World Anti-Doping Agency’s 2026 Prohibited List bans all three in and out of competition. BPC-157 is in section S0, substances with no government approval for human use. Thymosin beta-4 and its derivatives, such as TB-500, are in section S2.3, growth factors. The 2027 list keeps all three.^50,51

What isn’t known

Questions to ask a clinician