BPC-157 vs B7-33
Comprehensive side-by-side comparison of mechanisms, dosing, side effects, and research
Also: Body Protection Compound-157, Pentadecapeptide BPC 157
BPC-157 is a synthetic 15-amino-acid peptide (sequence Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val) based on a fragment of a protective protein found in human gastric juice. It is studied almost entirely in animals for tendon, ligament, gut, and tissue healing, and it has racked up hundreds of preclinical papers. The catch: it is not approved by any regulator for any use, and the human evidence is a handful of small pilot studies, not real clinical proof.
Also: B7-33 relaxin, Single-chain relaxin-2 analog
B7-33 is a 27-amino-acid, single-chain peptide cut down from the B-chain of human relaxin-2, the hormone that loosens tissue during pregnancy. Relaxin itself has strong anti-scarring effects but is a complex two-chain molecule that is hard and expensive to make, so an Australian group (Hossain and colleagues, 2016) designed B7-33 as a simpler version. In rodent models it reduced heart and lung fibrosis about as well as full relaxin. It has never been tested in humans.
Key Comparison Insights
- Both peptides belong to the Healing category, suggesting similar primary applications.
Detailed Comparison
| Attribute | BPC-157 | B7-33 |
|---|---|---|
| Category | Healing | Healing |
| FDA Status | Not FDA Approved | Not FDA Approved |
| Clinical Status | Pre I II III IV FDA | Pre I II III IV FDA |
| Mechanism of Action | The leading hypothesis is that BPC-157 promotes new blood vessel growth by upregulating the VEGFR2 receptor, the same receptor that drives angiogenesis, and by tapping into the nitric oxide system through the Akt-eNOS pathway. Better blood supply to injured tissue would, in theory, speed healing of tendons, muscle, and gut lining. Animal work also points to anti-inflammatory effects and interaction with growth-factor signaling. It is worth being blunt here: these mechanisms are mostly worked out in rodents, and the exact molecular target of BPC-157 has never been definitively pinned down. Treat the pathway story as a well-supported hypothesis, not settled fact. | B7-33 activates RXFP1, the relaxin receptor, but in an unusual way. In cells that naturally carry RXFP1 (like fibroblasts), it preferentially switches on the pERK1/2 pathway rather than the cAMP pathway, which made it the first described functionally selective (biased) RXFP1 agonist. Its anti-fibrotic action runs through RXFP1 paired with the angiotensin II type 2 receptor, increasing MMP-2, an enzyme that breaks down collagen. In other words, it pushes scar tissue to be broken down rather than built up. Two practical caveats: it binds RXFP1 poorly in standard engineered cell lines, so its potency depends heavily on the cell type, and it is short-lived in serum (roughly 6 minutes in lab tests), which is why researchers have tried fatty-acid versions to stretch its half-life. |
| Common Dosing | 250-500 mcg twice daily 1-2x daily | No established human dose Once to twice daily in mouse studies |
| Administration | Subcutaneous injection near injury site, or systemic | Intraperitoneal or subcutaneous injection (including osmotic minipumps) in rodents |
| Typical Duration | 4-12 weeks in most research protocols | 1-2 weeks in most rodent studies |
| Best Time to Take | Morning and evening (or near injury site timing) | No evidence-based timing |
Possible Side Effects May vary by individual |
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| Research Summary | The preclinical record is genuinely large. A 2025 narrative review in the journal Biomedicines counted hundreds of published animal studies showing BPC-157 accelerating healing across tendon, muscle, bone, gut, liver, and nervous-system injury models. The problem is the human side is nearly empty. That same review found only three published human pilot studies (knee pain injections, bladder injections for interstitial cystitis, and an intravenous safety trial) and concluded BPC-157 should be treated as investigational and not recommended for clinical use until proper trials exist. Pharmacokinetic work in rats and dogs found a very short elimination half-life (under 30 minutes after injection) and rapid breakdown into amino acid fragments, which raises real questions about how oral capsules sold online could deliver an intact peptide. Bottom line: lots of promising animal data, no completed randomized controlled trials in people, and no regulatory approval anywhere. | The founding paper (Hossain et al., Chemical Science, 2016) reported that B7-33 prevented or reversed organ fibrosis and dysfunction in three rodent models of heart or lung disease with potency similar to full relaxin-2, and, unlike native relaxin, it did not promote prostate tumor growth in mice. That last point matters because relaxin has been linked to tumor growth. Later mouse work extended the findings: Devarakonda et al. (Journal of the American Heart Association, 2020) gave 0.25 mg/kg twice daily by injection after a heart attack and found smaller infarcts, better heart function, and less fibrosis at 7 days. A 2023 follow-up from the original group confirmed that B7-33 cannot be shortened further without losing receptor binding. Important context: the full hormone (serelaxin) went all the way to a large phase 3 trial in acute heart failure (RELAX-AHF-2) and failed both primary endpoints, a reminder that strong animal anti-fibrotic data in this family have not translated easily to people. For B7-33 itself there are no human studies, no human pharmacokinetics, and no human safety data. |
Frequently Asked Questions: BPC-157 vs B7-33
What is the difference between BPC-157 and B7-33?
BPC-157 is a healing peptide that bpc-157 is a synthetic 15-amino-acid peptide (sequence gly-glu-pro-pro-pro-gly-lys-pro-ala-asp-asp-ala-gly-leu-val) based on a fragment of a protective protein found in human gastric juice. it is studied almost entirely in animals for tendon, ligament, gut, and tissue healing, and it has racked up hundreds of preclinical papers. the catch: it is not approved by any regulator for any use, and the human evidence is a handful of small pilot studies, not real clinical proof. B7-33 is a healing peptide that b7-33 is a 27-amino-acid, single-chain peptide cut down from the b-chain of human relaxin-2, the hormone that loosens tissue during pregnancy. relaxin itself has strong anti-scarring effects but is a complex two-chain molecule that is hard and expensive to make, so an australian group (hossain and colleagues, 2016) designed b7-33 as a simpler version. in rodent models it reduced heart and lung fibrosis about as well as full relaxin. it has never been tested in humans. The main differences lie in their mechanisms of action and clinical applications.
Which is better, BPC-157 or B7-33?
Neither is universally "better" - the choice depends on your specific goals. BPC-157 is typically used for healing purposes, while B7-33 is used for healing. Always consult with a healthcare provider to determine which may be appropriate for your situation.
Can BPC-157 and B7-33 be used together?
Some peptide protocols combine multiple compounds for synergistic effects. However, using BPC-157 and B7-33 together should only be considered under medical supervision, as both compounds have their own side effect profiles and potential interactions. Research on their combined use may be limited.