MOTS-c and SS-31 in Tested Sport: WADA Status and Testing

Where MOTS-c and SS-31 Sit on the 2026 List

WADA's 2026 Prohibited List, in force since January 1, 2026, treats the two best-known mitochondrial peptides very differently. MOTS-c is named on the list. SS-31 (elamipretide) is not, and since it became an approved prescription medicine in 2025 its anti-doping status has been an open question. An earlier version of this page said both were banned only through catch-all rules, with SS-31 held in S0 because it lacked approval. Both points are out of date.

The sections below explain how S4.4 and S0 work and then move on to testing and sanctions. A final section covers therapeutic use exemptions (TUEs). US drug law and the ethics of use are covered on our page about legal and ethical considerations for athletes.

MOTS-c Is Named Under S4.4.1

Section S4 of the list covers hormone and metabolic modulators. Its subsection S4.4.1 lists activators of AMP-activated protein kinase (AMPK), and the 2026 text gives BAM15, AICAR and "mitochondrial open reading frame of the 12S rRNA-c (MOTS-c)" as examples. USADA's explainer on the peptide reads it the same way: MOTS-c is prohibited at all times and explicitly listed.

The placement follows the biology. In the 2015 Cell Metabolism study that first described the peptide, MOTS-c acted through the AMPK pathway and protected mice against diet-induced obesity and insulin resistance. AICAR works on the same pathway, which is why the two sit side by side. The mouse data doesn't show that MOTS-c improves human performance, and WADA doesn't need that proof to list a substance in a class. The mouse endurance findings, and the absence of human performance data, are covered in MOTS-c for endurance and performance.

Two features of S4.4 matter for athletes. It applies in and out of competition, so timing use away from an event doesn't help. And the list states that substances in S4.3 and S4.4 are non-Specified, a label that sets the default sanction (see below).

How S0 Works, and Why SS-31 No Longer Clearly Fits

S0, non-approved substances, is the list's catch-all. The 2026 wording covers "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." Two conditions have to hold: no other section covers the substance, and no regulator anywhere has approved it for human use. BPC-157 is the best-known peptide in this class and is named there. Every substance in S0 is a Specified Substance.

SS-31 used to meet both conditions. On September 19, 2025, the FDA granted accelerated approval to Forzinity (elamipretide) to improve muscle strength in people with Barth syndrome, a rare inherited mitochondrial disease. With a current approval from a governmental regulator, elamipretide fails the second S0 condition. As of October 2026 it isn't named in any other section of the list.

That leaves its status unverified. WADA could treat it as caught by another class, such as the S4.4 metabolic modulators, or it may not be prohibited at all. We found no WADA or USADA statement on elamipretide since the approval, and we didn't run a Global DRO search for this page. Some third-party websites have published their own readings of the list, but none we saw cites a ruling from an anti-doping body. USADA's Drug Reference Line is the channel athletes in the US have for a written answer.

Two other changes are easy to misread:

• The 2026 list added cell components, including organelles such as mitochondria, to the existing ban on using normal or genetically modified cells. That rule is about the organelles themselves, not drugs that act on them, so it doesn't settle SS-31.
• The 2027 List, published in September 2026 and in force from January 1, 2027, adds "peptides" to the examples in S0. USADA's advisory says peptides in general are now named there and warns that unnamed peptides may still be prohibited. The "no current approval" condition stays in the 2027 text, so on our reading the change doesn't by itself capture an approved peptide like elamipretide.

What Testing Exists

For MOTS-c there is a published method. In 2019, researchers at the German Sport University Cologne (Knoop, Thomas and Thevis) described a liquid chromatography-mass spectrometry (LC/MS) assay for MOTS-c in blood plasma. It was validated under WADA's International Standard for Laboratories and detects the peptide down to 100 pg/mL. It also picks up animal forms of MOTS-c, four metabolites produced in lab incubations and two oxidation products. The authors presented it as a tool for future doping control. Whether accredited labs now run it routinely isn't public.

The same paper raised a complication. The body makes its own MOTS-c, so a test has to tell natural levels apart from an injected dose. A commercial ELISA kit reported natural levels of 45.9-218.5 ng/mL in 20 healthy volunteers, but the LC/MS method couldn't confirm those numbers. On our reading, the published work hasn't settled what a normal baseline looks like, and that would matter in a contested case.

For SS-31 we found no published doping-control method specific to elamipretide. Accredited labs use broad LC/MS screens for small peptides, but we couldn't confirm whether any of them include it.

Samples also don't expire quickly. Under the World Anti-Doping Code, a sample can be stored for up to 10 years after its first analysis and retested with newer methods, with the same legal effect as the original test. A clean result today isn't necessarily final.

When we checked USADA's public sanctions list in October 2026, no case named MOTS-c. That says little about detection on its own: the list covers only USADA's cases, and an empty result could reflect low use as easily as limited testing.

Sanctions

The Specified label decides the starting point. USADA summarizes the rule this way: a first violation involving a non-Specified substance carries a default four-year ban and loss of results, while a Specified substance starts at two years. The Code text behind that, Article 10.2 as quoted in USADA arbitration awards, works like this:

• Non-Specified substances, such as MOTS-c: four years, unless the athlete proves on the balance of probabilities that the violation wasn't intentional. Then the default is two years.
• Specified substances, such as BPC-157 in S0: two years, unless the anti-doping organization proves the violation was intentional. Then it's four.

The burden of proof flips between the two. For MOTS-c, the athlete has to show it wasn't intentional. Athletes are also strictly liable for whatever is found in their samples, a point USADA repeats in its 2027 advisory. These are the rules in force as of October 2026. For SS-31, the sanction question can't be answered until its classification is.

Therapeutic Use Exemptions

A TUE lets an athlete use a prohibited substance for a genuine medical need. Under WADA's International Standard for Therapeutic Use Exemptions, the athlete must show a diagnosed medical condition and that the substance is an indicated treatment with no reasonable permitted alternative. Its use also can't be expected to improve performance beyond a return to the athlete's normal health. Athletes apply to their national anti-doping organization or international federation, not to WADA.

For MOTS-c, USADA calls a TUE "highly unlikely" because the peptide has no approved therapeutic use. There is no diagnosis for which it is an indicated treatment.

SS-31 is the unusual case. Someone with Barth syndrome who is prescribed Forzinity has an approved drug for a diagnosed condition, which is what TUEs are for. If elamipretide turns out not to be prohibited, no TUE is needed. If it is prohibited, a TUE application would be the route. Either way, the athlete needs the classification first, and USADA's TUE Pre-Check Form exists for exactly that kind of question. A research-use vial sold online as "SS-31" is not Forzinity; our SS-31 overview covers the difference and the trial data.

What We Still Don't Know

• How WADA classifies elamipretide now that it is an approved drug, and whether Global DRO lists it.
• Whether any accredited lab runs the MOTS-c plasma assay routinely, and how a lab would set a cutoff above natural levels.
• Whether any lab has published or validated a method for elamipretide.
• Whether the broader S0 wording in the 2027 List changes how anti-doping bodies handle approved peptides in practice.