Evidence review: Open Peptide Project (verified against primary PubMed, ClinicalTrials.gov & FDA records) · Last checked 2026-10-27. ← Back to Evidence Library
Phoenixin (PNX-14, PNX-20): what the evidence says
At a glance
What it is: a peptide cut from the protein C4orf52, found mainly in two forms, phoenixin-14 and phoenixin-20. R1 First described in 2013 as a reproductive peptide; R2 in rats it appears to act through the receptor GPR173. R3
What the evidence says: Animal from lab and animal work, phoenixin is believed to help regulate reproductive hormones: in rats it raised the pituitary's response to GnRH and supported ovarian cycling. R2, R3 ⚪ No human treatment studies exist to date; human studies only measure blood levels, such as lower levels with more anxiety in 68 obese men and higher levels in women with PCOS. R4, R5 Whether it could help people is an open question worth future study.
Biggest risks: unknown: human safety has never been studied.
Rating
| Human Human evidence | None for taking it; observational blood-level studies only R4, R5 |
| Animal Animal / lab evidence | Rats (reproductive hormones) R2, R3 |
| Regulatory | Not approved anywhere · not on FDA's 503A or 503B bulk-substance category lists and not on FDA's compounding safety-risk page R6, R7, R8 · not named on WADA's 2026 list; as a drug not approved anywhere for human use it falls under S0 (non-approved substances) R9 |
| Established human dose | No |
Evidence verdict: Fertility, anxiety or appetite: No human data (animal studies only) · Other uses: No human data (blood-level studies only)
This page reports what studies used. It is not dosing advice.
Legend: HUMAN data · ANIMAL / LAB data · UNKNOWN · UNVERIFIED: not yet confirmed against a primary source
About the evidence: the human studies are small and measure blood levels only. The discovery paper's team included employees of Phoenix Pharmaceuticals. R2
What is it?
Related pages: kisspeptin-10, nesfatin-1, spexin.
Does it work?
- Animal Reproduction: in rats it raised the pituitary's response to GnRH and supported ovarian cycling. R2, R3
- ⚪ Anxiety: in 68 obese male inpatients, higher blood phoenixin went with lower anxiety scores. R4
- ⚪ PCOS: phoenixin-14 was higher in women with PCOS. R5
- ⚪ CT.gov lists only observational studies (searched Oct 27, 2026).
Is it safe?
- ⚪ No human safety data.
- It interacts with reproductive hormone signaling in animals, so effects on fertility hormones are possible but untested. R3
Gray-market vials: extra risks
A gray-market vial has no quality control and no guarantee of identity, strength or sterility. We test retail vials blind under the Open Peptide Standard; see /tests/. A passing test covers one batch on one date and does not mean the compound is safe.
Is it legal?
- US: not FDA-approved; no Drugs@FDA application found (openFDA searched Oct 27, 2026).
- Compounding: not on FDA's 503A or 503B bulk-substance category lists and not on FDA's compounding safety-risk page. R6, R7, R8
- Sport: not named on WADA's 2026 list; as a drug not approved anywhere for human use it falls under S0 (non-approved substances) R9.
Study details
Study details
These are amounts researchers used, not recommendations.
| Study | People / model | Route | Amount used | Follow-up | Reported | Citation |
|---|---|---|---|---|---|---|
| No human dosing study | — | — | — | — | — | — |
| Stein 2016 | Female rats | Brain injection | Per protocol | Short-term | LH release; GPR173-dependent | PMID 27440717 |
Full reference list (PubMed, CT.gov, FDA and WADA checked Oct 27, 2026)
- R1 Yuan T, et al. Protein Pept Lett. 2017. PMID 28176660
- R2 Yosten GL, et al. J Neuroendocrinol. 2013. PMID 22963497
- R3 Stein LM, et al. Am J Physiol Regul Integr Comp Physiol. 2016. PMID 27440717
- R4 Hofmann T, et al. Peptides. 2017. PMID 27989611
- R5 Ullah K, et al. Clin Chim Acta. 2017. PMID 28624500
- R6 FDA, 503A bulk drug substances categories list (updated May 14, 2026). https://www.fda.gov/media/94155/download
- R7 FDA, 503B bulk drug substances categories list (updated Mar 21, 2025). https://www.fda.gov/media/94164/download
- R8 FDA, Certain bulk drug substances for use in compounding that may present significant safety risks (content current Apr 22, 2026). https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
- R9 WADA. The 2026 Prohibited List, S0 Non-approved substances; full list checked, compound not named. https://www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf
Disclaimer
This page is for education and harm reduction, not medical advice or a recommendation to use Phoenixin (PNX-14, PNX-20). This is a naturally occurring peptide that has never been tested as a treatment in people and is not approved anywhere. Products sold under this name are unregulated research chemicals. Report problems to FDA MedWatch (https://www.fda.gov/safety/medwatch).