Legal Landscape of Peptides in Sports

How the Prohibited List is organized

The World Anti-Doping Agency (WADA) publishes its Prohibited List once a year. As of October 2026, the 2026 List is in force, and the 2027 List has been published and takes effect on January 1, 2027. The peptide sections are numbered the same way in both, so the section numbers on this page apply to either year.

Classes S0 to S5 and the prohibited methods (M1 to M3) apply in and out of competition. S6 to S9 apply in competition only. Nearly every peptide sold online sits in S0 or in the S2 and S4 classes, all prohibited at all times.

Each class opens with a line saying whether its substances are Specified or non-Specified. That label follows the substance into any anti-doping case, so a peptide's section tells you more than the bare fact that it's banned.

The two growth hormone subsections follow the growth hormone pathway: S2.2.3 covers the hormone and its pieces, and S2.2.4 covers anything that tells the pituitary to release more of it.

S0 is checked last

S0 reads: "Any pharmacological substance which is not addressed by any of the subsequent sections of the List and with no current approval by any governmental regulatory health authority for human therapeutic use ... is prohibited at all times." Both conditions have to hold. The first one makes S0 a residual class. A peptide that fits a description in S2 or S4 goes there, even if no regulator has ever approved it.

That ordering explains a common error in older guides. TB-500 has never been approved anywhere, but it's named in S2.3 as a derivative of thymosin beta-4, so it isn't an S0 substance. BPC-157 is the peptide WADA names in S0, alongside non-peptides such as DNP and troponin activators.

Approval also only matters for S0. Tesamorelin and sermorelin have both been FDA-approved prescription medicines, and the List still names them in S2.2.4. A prescription doesn't remove a substance from S2 or S4; for a tested athlete with a genuine medical need, that's what a Therapeutic Use Exemption is for.

Two approved peptides fall into a gap. Bremelanotide (PT-141, approved in the US as Vyleesi) and elamipretide (SS-31, given FDA accelerated approval as Forzinity in September 2025) aren't named anywhere on the 2026 List. Because both now have a current approval, they no longer meet S0's "no current approval" test. Whether another section catches either one is unverified: as of October 2026, we couldn't confirm their status from WADA's text. Melanotan II isn't named either; it has no approval, so on our reading of the S0 definition it falls there unless another section applies.

What "similar chemical structure or similar biological effect(s)" means

The S2 heading says: "The following substances, and other substances with similar chemical structure or similar biological effect(s), are prohibited." The subsections then give examples "including, but not limited to" the named compounds. S2.3 ends with an open clause that reaches other growth factors and modulators acting on muscle and connective tissue; the full wording lists six kinds of effect, from protein synthesis to fibre type switching.

In practice, the names on the List are examples, not a complete inventory. A new GHRP sold under a lab code is still an S2.2.4 substance if it acts on the same receptor. A relabeled product or a multi-peptide blend vial still contains whatever it contains. USADA's 2027 athlete advisory makes the same point: prohibited peptides may be sold "under different names or slang terms," and some experimental ones aren't yet on the anti-doping community's radar.

S0 doesn't need the "similar" wording, because its definition already reaches any unapproved pharmacological substance that no other section covers.

Specified vs non-Specified

The List quotes Article 4.2.2 of the World Anti-Doping Code: for the purposes of Article 10 (sanctions), all prohibited substances are Specified unless the List says otherwise. The Code's comment, also quoted in the List, says Specified substances "should not in any way be considered less important or less dangerous than other doping substances." They're substances "more likely to have been consumed or used by an Athlete for a purpose other than the enhancement of sport performance."

For peptides, the 2026 List assigns the labels by class:

• S0: all Specified.
• S2: all non-Specified.
• S4: S4.1 and S4.2 (aromatase inhibitors and anti-estrogens) are Specified; S4.3 and S4.4 are non-Specified.

So BPC-157 is a Specified substance. TB-500 and MOTS-c are non-Specified, even though vendors often sell them side by side with BPC-157. How the label changes the burden of proof and the length of a ban is covered in our article on peptide detection and sanctions. Why a compound qualifies for the List at all, under WADA's rule that a substance must meet two of three criteria, is covered in why WADA lists a peptide.

What changes in the 2027 List

According to USADA's athlete advisory on the 2027 List, the S0 definition now lists "peptides" next to designer drugs among its examples of non-approved substances. USADA describes this as "peptides" in general now being named as prohibited substances in S0.

The change makes explicit what S0 already covered. It doesn't move any peptide out of S2 or S4, because the residual rule still applies. A federation-hosted copy of the 2027 List text shows BPC-157 still named in S0, TB-500 in S2.3 and MOTS-c in S4.4.1.

Semaglutide and tirzepatide remain unprohibited. WADA's 2026 summary of modifications clarified that urine monitoring of semaglutide also covers tirzepatide, and USADA lists both in the 2027 Monitoring Program for testing in and out of competition. Monitoring means accredited labs look for them so WADA can study patterns of use; it is not a ban.

What this means for untested lifters

The List is one of WADA's International Standards, which WADA describes as mandatory for all Code Signatories. It binds athletes through the rules of those organizations. A lifter who never competes, or who competes in a federation that doesn't test, isn't bound by it, and the List itself isn't a law. In a federation that advertises drug testing, its own rulebook decides; some adopt the WADA List and others write their own, and we didn't survey them for this page.

Some lifters treat the List as a roadmap to what works, which reads too much into it. A listing can rest on potential to enhance performance or on health risk, and it isn't evidence of an effect in people. BPC-157 is named in S0, yet a systematic review of its use in orthopaedic sports medicine found 36 relevant studies through mid-2024, and 35 of them were preclinical.

For untested lifters, the rules that apply are the law where they live and the quality of what's in the vial.

• Law. In the US, an FDA warning letter sent to a peptide seller on August 24, 2026 says "research use only" labels didn't stop its products being treated as unapproved new drugs, because the website made drug claims and sold bacteriostatic water for reconstituting them. Letters like this are aimed at sellers. How FDA rules differ from WADA rules is covered in FDA law vs. WADA rules for peptides.
• Product quality. An April 2026 preprint (not yet peer-reviewed) analyzed 6,441 samples of 14 peptides from a public third-party testing dataset. Depending on how strict the standard was, 41.6% to 71.1% failed basic quality criteria, 156 reports didn't contain the stated peptide, and measurable endotoxin turned up in 15% of the 243 samples tested for it.

What to watch next

The open question for 2027 is how WADA treats approved peptides that aren't named on the List. PT-141 and elamipretide are the obvious cases. Semaglutide and tirzepatide stay in the Monitoring Program for 2027, so any move to prohibit them would show up first in a future List draft. WADA's review cycle starts each January and ends with publication of the next List by October 1, so the 2028 List is due by October 2027.