PSIPeptide Science Institute

Peptide Science Institute

Research and evidence, published for every peptide.

Tools

Three ways to navigate PSI

FDA Status Tracker

Regulatory status for all 147 compounds the library tracks. 19 FDA-approved, plus categorization for every compound with a clear regulatory position.

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Compare peptides

Side-by-side evidence comparisons. Mechanism, research depth, and regulatory position for the questions physicians ask most.

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Find a physician

88 physicians verified against PSI's five-gate standard across New York, Miami, Los Angeles, Dallas, and Austin.

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Spotlight

Peptides people are talking about

These are the peptides getting the most attention right now, across research communities, biohacker spaces, functional health clinics, and mainstream health media. For many people, this is the first place they hear about peptides. Each entry below links to the full assessment: what the research shows, what stage it's at, and whether a doctor can currently prescribe it.

Semaglutide

The GLP-1 medicine behind Ozempic and Wegovy. The biggest story in obesity medicine in a generation. FDA-approved for type 2 diabetes and for weight management, with cardiovascular outcomes data that has changed how obesity is treated clinically.

Read the full assessment →

Retatrutide

The next-generation weight-loss compound in late-stage clinical trials, producing the largest average weight loss ever recorded in a controlled drug study. Not yet FDA approved, and cannot yet be prescribed.

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BPC-157

The recovery peptide that went viral in sports and biohacker communities over the past few years, and a frequent prescribing decision in functional health practice. Animal evidence across tendons, ligaments, gut lining, and liver is extensive and consistent. Human trials exist but remain limited. Not FDA approved. A doctor can currently have it prepared through a specialty pharmacy.

Read the full assessment →

Semax

Prescribed in Russia since the 1990s for stroke recovery and cognitive disorders, after a research pathway that started in the Soviet-era Russian Academy of Sciences. Not FDA approved in the United States. Research focuses on BDNF, a protein critical for brain cell survival and the formation of new neural connections.

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Thymosin Alpha-1

Approved as Zadaxin in more than 35 countries for hepatitis B, hepatitis C, and as an immune modulator in sepsis and cancer care. Studied for its role as an immune modulator, which rebalances immune function rather than suppressing it. Not FDA approved in the United States, despite substantial international clinical trial evidence.

Read the full assessment →

Evidence

The regulatory picture for peptides

PSI maintains a live tracker of every peptide compound's regulatory status. The landscape is more nuanced than "approved" or "not approved." A handful of peptides have completed the full FDA pathway and are prescribed as conventional medications: semaglutide, tirzepatide, liraglutide, tesamorelin, and a small number of others. A much larger group, including most peptides studied in functional medicine, is not FDA approved but is allowed through compounding pharmacies, legally prescribed by physicians. A third group was restricted in recent FDA actions and is under active reclassification review.

For any specific peptide, regulatory status changes over time, sometimes quickly. The tracker reflects the current state and is updated as the FDA publishes actions.

"Not FDA approved" does not usually mean "does not work." It usually means no company had a patent strong enough to pay for the trial.

PSI editorial, April 2026

View the FDA Status Tracker →

Research depth

Where the science is thickest

Research depth is not the same as effectiveness, but it is where the science has accumulated.

Liraglutide	FDA Approved	5,576
Semaglutide	FDA Approved	4,520
LL-37	Human Trials	3,096
Tirzepatide	FDA Approved	1,849
TB-500	Human Trials	1,050
Thymosin Alpha-1	Human Trials	856
GHK-Cu	Human Trials	600
BPC-157	Human Trials	212

Browse all 147 compounds →

Preclinical
Research exists only in cells, test tubes, or molecular modeling. No animal or human has received the compound in a published study. Most compounds at this stage are being investigated because the mechanism is interesting to a research laboratory.
Animal Studies
Research exists in animal models, with no published human trials yet. This is the normal research depth for most peptides. A strong animal evidence base replicated across different research groups is a meaningful signal, not a deficiency.
Human Trials
At least one published human study exists. For research peptides without commercial development, even small pilot studies are notable additions to the evidence base. FDA-approved peptides at this tier have substantially more extensive human data.
FDA Approved
The compound completed the full FDA approval pathway, including Phase III trials. FDA Approved is a separate regulatory category, not a ranking tier.

Read the full editorial standards →

Browse

Peptides by research area

147 compounds grouped by the research question they address. Research area is not the same as therapeutic indication.

Tissue repair

BPC-157, TB-500, GHK-Cu

Weight management

Semaglutide, Tirzepatide, Retatrutide

Cognitive function

Semax, Selank, Cerebrolysin

Longevity & aging

Epithalon, MOTS-c, GHK-Cu

Metabolic health

Tesamorelin, AOD-9604, CJC-1295

Immune support

Thymosin Alpha-1, LL-37, Thymulin

Growth hormone

Ipamorelin, Sermorelin, MK-677

Sexual health

PT-141, Kisspeptin, Melanotan II

Verified care

Finding a physician who knows peptide research

Not every doctor is comfortable prescribing peptides, and the legal status varies compound-by-compound. PSI maintains a directory of 88 physicians across 5 cities who have been individually verified against a five-gate standard: board certification, active state license, zero disciplinary actions, direct peptide experience, and active clinical practice.

New York20 Miami20 Los Angeles18 Dallas16 Austin14

See all 88 verified physicians →