Phoenixin
A small brain-and-gut peptide the body makes itself, first known for switching up reproductive hormones and now tied to appetite, mood, memory and metabolism; it has never been given to people as a treatment
Phoenixin is a neuropeptide discovered in 2013, cut from a larger protein called SMIM20 and acting on an orphan receptor, GPR173. It comes in two active forms, a 14- and a 20-amino-acid peptide (PNX-14 and PNX-20). It was first noticed in the hypothalamus, where it strengthens the release of luteinizing hormone driven by GnRH, linking it to the control of the reproductive cycle. Since then animal and laboratory work has tied it to food intake, anxiety, memory, itch, fluid balance, the heart and energy metabolism, and human studies have measured its blood levels in conditions such as polycystic ovary syndrome and diabetes. It is a signalling molecule the body makes itself, studied as a research peptide — it is not an approved medicine and has never been given to people in a published trial.
No established human dose Details ↓
Recommended Dosing
No established human dose
Phoenixin is an endogenous peptide that has never been given to people as a treatment. The human studies carded here only measured how much phoenixin circulates in blood (for example in polycystic ovary syndrome and type 2 diabetes), not what happens when it is administered, and no regulator has approved any dose.
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What is it?
Phoenixin was found in 2013 by researchers looking for new signalling peptides hidden inside known proteins. They spotted a short, highly conserved stretch at the end of a small protein called SMIM20 (then named C4orf52) and showed the body cuts it into two active peptides, 14 and 20 amino acids long, both carrying an amide cap. Because the sequence was so well preserved across species, from fish to humans, it looked like something biologically important — hence the name, after the mythical bird, for a peptide that had been hiding in plain sight.
Its first clear job was reproductive. In the hypothalamus and pituitary, phoenixin potentiates the release of luteinizing hormone that gonadotropin-releasing hormone (GnRH) triggers, and it raises the expression of GnRH and of kisspeptin, the gatekeeper of puberty and fertility. Knocking it down in female rats lengthened the estrous cycle. Its receptor was tracked down to GPR173, an orphan G-protein-coupled receptor, which it signals through to raise cyclic AMP and activate protein kinase A inside hypothalamic neurons.
The reproductive story turned out to be only part of it. Phoenixin and its receptor are found well beyond the reproductive axis — in other parts of the brain, in sensory nerves, the heart, the gut, fat tissue and the pancreas — and animal studies have linked it to a surprising range of effects: changing how much animals eat, easing anxiety-like behaviour, improving memory retention, triggering the sensation of itch, stimulating the release of vasopressin to control body-fluid balance, protecting cells from stress and inflammation, and supporting the mitochondria that power neurons. It also talks to other appetite peptides, notably nesfatin-1, with which it is co-expressed.
In people the evidence so far is observational: researchers measure how much phoenixin circulates in different conditions rather than giving it as a drug. Blood phoenixin-14 is reported higher in women with polycystic ovary syndrome and rises with body-mass index, tracking with luteinizing hormone, testosterone and insulin resistance; it is reported lower in people with type 2 diabetes; and it is higher in pregnant women with severe morning sickness. These associations suggest phoenixin sits at a crossroads of reproduction and metabolism, but they do not show that changing it helps or harms.
Phoenixin is an endogenous signalling peptide and a laboratory research tool, not a medicine. No published study has given phoenixin to people as a treatment, it is approved nowhere, and what is sold online as “phoenixin” is an unregulated research chemical. Nothing here is a dose or a therapy; this page records what the published science says about a peptide the body makes for itself.
Mechanism of Action
Phoenixin is a signal the body makes itself. It is cut from a larger protein and acts on the receptor GPR173 to tune the release of other hormones and to protect and support cells, most clearly in the hypothalamus.
GPR173 and reproductive hormones
Phoenixin binds the orphan receptor GPR173 on hypothalamic and pituitary cells, raising cyclic AMP and protein kinase A, which potentiates GnRH-driven luteinizing-hormone release and increases GnRH and kisspeptin expression (PMID 29671415) — the basis of its link to the reproductive cycle.
Appetite, mood and the gut-brain axis
Phoenixin and its receptor sit in brain and gut circuits that govern feeding, anxiety and memory, and it is co-expressed with the appetite peptide nesfatin-1; animal work links it to changes in food intake and anxiety-like behaviour (PMID 29671415).
Cell protection and metabolism
Beyond signalling, phoenixin protects cells from stress: it eased diet-induced fatty liver in mice through SIRT1/AMPK and NRF2/HO-1 (PMID 33061293) and supported mitochondrial biogenesis in neurons via CREB and PGC-1α (PMID 32236796), and it stimulates vasopressin release to help control body-fluid balance (PMID 29364701).
Published Research
These are studies of phoenixin read from their PubMed abstracts on November 5, 2026. The human record is observational — how much phoenixin circulates in polycystic ovary syndrome and in type 2 diabetes; the mechanistic work is in animals and cells, covering vasopressin release, protection against fatty liver, and mitochondrial support, with a review of the receptor and signalling. Phoenixin has not been given to people as a treatment in any published study.
Blood phoenixin-14 in polycystic ovary syndrome
In 50 women with polycystic ovary syndrome (PCOS) and 30 controls, serum phoenixin-14 measured by ELISA was significantly higher in the PCOS groups than in matched non-PCOS women, both lean and overweight, and rose roughly three-fold with higher body-mass index. PNX-14 correlated positively with BMI, insulin resistance (HOMA-IR), luteinizing hormone and testosterone, tying the peptide to the reproductive and metabolic features of PCOS. An observational levels study, not a trial of giving phoenixin.
Phoenixin levels in type 2 diabetes
A case-control study of 36 people with type 2 diabetes and 36 healthy controls measured serum phoenixin-14 and phoenixin-20 by ELISA. Both were significantly lower in the diabetes group, and both fell as body-mass index, fasting glucose, HbA1c and insulin resistance rose. The authors suggested phoenixin might serve as a marker related to the development of type 2 diabetes. Again an observational study of circulating levels, not an intervention.
Phoenixin and vasopressin release (rats)
Beyond reproduction, phoenixin and its receptor GPR173 are present in the hypothalamic nuclei that make vasopressin. Injected into the brains of conscious rats, phoenixin raised circulating vasopressin (but not oxytocin), activated the supraoptic nucleus and directly depolarised paraventricular neurons, pointing to a role in the control of body-fluid and electrolyte balance.
Phoenixin-14 against fatty liver (mice)
Mice fed a high-fat diet and given phoenixin-14 by gavage for ten weeks developed less obesity and fatty liver than untreated mice: lower liver enzymes, cholesterol and triglycerides, less lipid deposition and fibrosis, more antioxidant defence, and less inflammation, through the SIRT1/AMPK and NRF2/HO-1 pathways. A preclinical protective effect in a diet model of non-alcoholic fatty liver disease.
Phoenixin-20 and mitochondrial biogenesis
In cultured neuronal cells, phoenixin-20 increased the master mitochondrial regulators PGC-1α, NRF-1 and TFAM, raised mitochondrial DNA and respiratory rate and boosted ATP production, acting through activation of the CREB pathway and its receptor GPR173. The work proposed phoenixin as a support for mitochondrial health in neurons, relevant to neurodegeneration research.
The receptor, signalling and functions
A review tracing phoenixin from its reproductive role — potentiating GnRH-stimulated LH release and driving kisspeptin and GnRH gene expression — to the identification of its receptor GPR173 and its protein-kinase-A signalling, and to its wider roles in feeding, memory, anxiety and the heart. It frames phoenixin as a pleiotropic neuropeptide whose full physiology is still being mapped.
No Established Human Dose
Phoenixin is an endogenous peptide that has never been given to people as a treatment. The human studies carded here only measured how much phoenixin circulates in blood (for example in polycystic ovary syndrome and type 2 diabetes), not what happens when it is administered, and no regulator has approved any dose. Animal studies gave it into the brain or by gavage at microgram-to-nanogram amounts that do not carry over to people, so no amount is printed here.
What this rests on: PMID 37140302, PMID 38213155, PMID 29364701, PMID 33061293.
Educational information, not medical advice. The doses on this page come from approved labels, published studies and, where no study exists, amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
What a Buyer Needs to Know
What is sold, how it is mixed, stored and taken, and what is known about its safety, quality and legal status. Each part names its source. Where we have none, it says unknown.
What is sold
Unknown: we hold no label and no published test that says what forms or vial sizes Phoenixin is sold in. A vial's own label is a seller's claim, not a source.
Mixing a vial: a worked example
Unknown: no human dose of Phoenixin has been established (see No Established Human Dose below), so there is no amount to work out. The reconstitution calculator does the arithmetic for any vial, water and dose.
Storage before and after mixing
Unknown: no label or published stability study on file says how to store Phoenixin, before or after mixing. The mixing guide sets out the general rules, with their sources: keep a mixed vial in the fridge, and use it promptly, as the bacteriostatic water label says of any drug dissolved in it. The 28 days often quoted is the limit for an opened multiple-dose vial from a manufacturer, an outer limit set for sterility, not a time a mixed solution has been shown to keep. Nobody has published how long Phoenixin stays intact once mixed.
How it is taken
Unknown: with no established human dose, there is no established way of taking Phoenixin. What the human studies gave and how is set out under No Established Human Dose.
What to expect, and when
How long it stays in the body: a half-life of not established for humans; an endogenous signalling peptide. After about five half-lives almost none is left.
When effects appear: unknown; no source on this page gives a time to effect for Phoenixin. Results reported in the studies are under Published Research.
Source: half-life: PMID 29671415.
Side effects, and when to stop or get help
From the Side Effects section: No human adverse-event data exist: no published study has administered phoenixin to people; Human research measures its circulating levels only (PMIDs 37140302, 38213155); Animal effects are dose- and route-specific (e.g. brain injection, gavage) and not transferable to people; Material sold online as “phoenixin” is an unregulated research chemical of unverified content. Full list and cautions ↓
When to stop or get help: unknown; no label or trial on file sets rules for stopping Phoenixin. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“Phoenixin is an endogenous peptide that has not been given to people as a drug, so there is no human safety profile; the points below reflect that research status”).
Interactions
Unknown: a PubMed search for human interaction studies of Phoenixin (reviewed 2026-11-05) found none. Unknown is not the same as safe to combine.
Every peptide's record, with its source: the interaction matrix.
Checking what you bought
Unknown: no published independent test of Phoenixin products is in our lab-results database yet, so how products sold under this name measure up is not known.
To read a certificate of analysis, paste it into the COA decoder. Trust & Verification explains what independent testing can and cannot show.
Legal status
US: Research Chemical (Not a drug: Drugs@FDA and the openFDA label endpoint hold no record, and FDA GSRS and ChEMBL hold no substance record for phoenixin (searched November 5, 2026)). Sport: Not on the 2026 List.
Country by country ↓ · Regulatory tracker
Source: this entry's approval status and the WADA Prohibited List, as in Legal Status below.
Side Effects & Contraindications
Reported Side Effects
Phoenixin is an endogenous peptide that has not been given to people as a drug, so there is no human safety profile; the points below reflect that research status.
Contraindications & Cautions
Phoenixin has no approved use and no label. These points reflect its endogenous, research status.
Legal Status
Phoenixin is an endogenous human neuropeptide studied as a research compound; it is not a drug and is not approved in any country.
Frequently Asked Questions
?What is phoenixin?
A neuropeptide the body makes itself, discovered in 2013 and cut from a protein called SMIM20. It comes in two forms, phoenixin-14 and phoenixin-20, and acts on the receptor GPR173. It was first found to boost reproductive hormone release and is now linked to appetite, mood, memory and metabolism.
?What does it do?
In the hypothalamus it strengthens GnRH-driven luteinizing-hormone release and raises kisspeptin, tying it to the reproductive cycle (PMID 29671415). Animal and cell studies also link it to food intake, anxiety, memory, vasopressin release, and protection of liver and nerve cells (PMIDs 29364701, 33061293, 32236796).
?Has it been tested in people?
Only by measurement, not as a treatment. Studies report that blood phoenixin-14 is higher in women with polycystic ovary syndrome and rises with BMI (PMID 37140302), and lower in people with type 2 diabetes (PMID 38213155). No published study has given phoenixin to people.
?Is it approved or available to buy?
No. Phoenixin is not a medicine, has no FDA application or label, and is approved nowhere. Material sold online as phoenixin is an unregulated research chemical. Grey Peptides lists no sellers and recommends no source; this page records the published science.
References
- [clinical-trial] Cundubey CR, et al. "Serum Phoenixin-14 levels of women with polycystic ovary syndrome increase proportionally with BMI." Eur Rev Med Pharmacol Sci, 2023;27(8):3519-3525. PMID: 37140302.
- [clinical-trial] Can U, et al. "The Levels of Phoenixin-14 and Phoenixin-20 in Patients with Type 2 Diabetes Mellitus." Endocr Metab Immune Disord Drug Targets, 2024;24(11):1315-1322. PMID: 38213155.
- [animal] Gasparini S, et al. "Novel regulator of vasopressin secretion: phoenixin." Am J Physiol Regul Integr Comp Physiol, 2018;314(4):R623-R628. PMID: 29364701.
- [animal] Yang F, et al. "Phoenixin 14 Inhibits High-Fat Diet-Induced Non-Alcoholic Fatty Liver Disease in Experimental Mice." Drug Des Devel Ther, 2020;14:3865-3874. PMID: 33061293.
- [mechanism] Yang Y, et al. "Phoenixin 20 promotes neuronal mitochondrial biogenesis via CREB-PGC-1α pathway." J Mol Histol, 2020;51(2):173-181. PMID: 32236796.
- [review] Mcilwraith EK, et al. "Phoenixin: uncovering its receptor, signaling and functions." Acta Pharmacol Sin, 2018;39(5):774-778. PMID: 29671415.
- [other] PubChem, read November 5, 2026: phoenixin-14 (CID 169450633, CAS 1415039-79-0, C75H110N18O20, MW 1583.8; sequence DVQPPGLKVWSDPF-NH2) and phoenixin-20 (CID 169450632, C101H153N25O29, MW 2181.4), the two active amidated isoforms. https://pubchem.ncbi.nlm.nih.gov/compound/169450633
- [other] Phoenixin is cleaved from small integral membrane protein 20 (SMIM20, formerly C4orf52) and acts on the orphan G-protein-coupled receptor GPR173 (SREB3); discovered and named by Yosten and colleagues in 2013, as reviewed in the Acta Pharmacologica Sinica article carded on this page (read November 5, 2026).
- [other] US FDA, Drugs@FDA and the drug label endpoint (openFDA), searched November 5, 2026: no application and no label record for phoenixin. It is an endogenous human neuropeptide, not a registered drug; FDA GSRS and ChEMBL hold no substance record for it.
Sources & Citations
The six studies carded above were read from their PubMed records on November 5, 2026. Structure and identifiers come from PubChem (phoenixin-14 CID 169450633, phoenixin-20 CID 169450632); the precursor SMIM20 and receptor GPR173 are from the cited review (PMID 29671415); the absence of US approval and of a drug substance record from Drugs@FDA, openFDA, FDA GSRS and ChEMBL was checked the same day. Grey Peptides sells nothing and links to no vendor.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.