Last reviewed 15 September 2026. Products on this site are supplied strictly for laboratory research and are not for human consumption. This guide summarises published research; it is not medical advice.
Two classes, one search term
SARMs and research peptides are searched for together, sold by the same suppliers and discussed on the same forums, and that has blurred a real chemical difference. A SARM is a small synthetic molecule, usually a few hundred daltons, designed to bind the androgen receptor selectively. A peptide is a short chain of amino acids, typically five to fifty of them, that signals through its own receptor or acts on a tissue process such as angiogenesis or cell migration. They are studied for different reasons, behave differently on the bench, and are handled and stored differently. This guide sets the two classes side by side so a research buyer can see what the literature actually supports for each.
How they act
Every SARM in the research literature works by the same route: it enters the cell, binds the androgen receptor, and changes which genes that receptor switches on. The compounds differ in how tightly they bind, whether they are full or partial agonists, and how selective they are between muscle and bone on one side and the prostate on the other. Ostarine, LGD-4033, RAD-140, Andarine, S-23, YK-11 and ACP-105 are all variations on that theme, although YK-11 is sometimes classed separately because it also acts on myostatin signalling in cell culture. Two compounds sold alongside SARMs are not SARMs at all: Cardarine activates PPAR-delta, a receptor involved in fat and glucose metabolism, and Stenabolic acts on the REV-ERB proteins that regulate circadian genes.
Research peptides have no single mechanism. BPC-157, a fragment of a protein found in gastric juice, has been studied for its effects on blood vessel growth and tendon and gut tissue in rodents. TB-500, a fragment of thymosin beta-4, acts on actin, the protein that lets cells move, and has been studied in wound models. GHK-Cu is a copper-binding tripeptide studied in skin and wound healing. The growth hormone secretagogue peptides, CJC-1295 and ipamorelin among them, act on the pituitary in the same broad way that the small molecule MK-677 does. Each peptide has its own receptor, its own literature and its own evidence gap.
Where the evidence stands
| Compound | Class | Highest published stage | What was measured |
|---|---|---|---|
| Ostarine (MK-2866) | SARM | Phase III (human) | Lean mass, physical function in cancer cachexia |
| LGD-4033 | SARM | Phase I (human) | Safety, lean mass over 21 days |
| RAD-140 | SARM | Phase I (terminated) | Breast cancer, muscle |
| MK-677 | GH secretagogue (small molecule) | Two-year human study | Bone density, lean mass in older adults |
| BPC-157 | Peptide | Preclinical (rodent) | Tendon, gut and vessel healing |
| TB-500 (Tβ4 fragment) | Peptide | Preclinical; parent Tβ4 phase II | Wound healing, cardiac repair |
| GHK-Cu | Peptide | Small human skin studies | Skin and wound healing |
| CJC-1295, ipamorelin | GH secretagogue peptides | Phase I to II (CJC-1295) | Growth hormone release |
The pattern in the table is the important point. The most studied SARM, Ostarine, has phase III data in humans; several others have phase I safety data. Almost none of the research peptides sold for laboratory use have been through a registered human trial for the purposes people discuss online; BPC-157 and TB-500 in particular have rodent data and case reports only. A buyer comparing the two classes on evidence is comparing a compound with human trial data against one with animal data, which is a bigger difference than the marketing on either side suggests.
Stability, storage and format
The practical difference is the one most buyers meet first. SARMs are stable small molecules: supplied as capsules, they keep at room temperature, away from light and moisture, for the shelf life on the label, and the capsule format gives a fixed quantity per unit that can be verified on a certificate of analysis. Peptides are fragile. They are supplied lyophilised, a freeze-dried powder in a sealed vial, and must be kept refrigerated at 2 to 8 degrees Celsius or frozen for long storage; once reconstituted in the laboratory they degrade over days to weeks even when cold. Peptide purity is measured by HPLC and identity by mass spectrometry, and a certificate of analysis for a peptide should show both, because a peptide that has degraded in transit will still look like a white powder. Some peptides are also offered in capsule form; the published oral bioavailability of most peptides is low, which is one reason the research literature uses injected forms in animals, and a reason to treat oral peptide products as a different research question rather than an equivalent.
The legal position in the UK, 2026
Neither class is a controlled drug under the Misuse of Drugs Act 1971, with the exception of a small number of hormones and hormone analogues that are scheduled separately and are not sold on this site. Neither class is a licensed medicine, so neither can be sold for human consumption, and the MHRA treats any product supplied with dosing instructions, reconstitution instructions for use in people, or health claims as an unlicensed medicine. Both may be sold as research chemicals. In sport, SARMs are prohibited at all times under WADA class S1.2 and most research peptides fall under S2 (peptide hormones, growth factors and related substances). Some peptides that are marketed elsewhere as research compounds are in fact prescription-only medicines or unlicensed medicines under active MHRA enforcement; SARMs Store does not stock those and this guide does not cover them. Full guide: Are SARMs legal in the UK?
What to check before buying either
For a SARM: strength per capsule, capsule count, batch number, and a certificate showing identity and purity for that batch. For a peptide: the quantity per vial in milligrams, the purity by HPLC, the identity by mass spectrometry, the batch number, and evidence the product was kept cold in transit. In both cases the certificate should be batch specific, not a generic document. Every Dexterz Labs and Origin Peptides batch is independently tested and its certificate of analysis is published on the product page and the Lab testing page. See how to read a certificate of analysis.
Key references
Dalton JT, Barnette KG, Bohl CE, et al. The selective androgen receptor modulator GTx-024 (enobosarm) improves lean body mass and physical function in healthy elderly men and postmenopausal women. Journal of Cachexia, Sarcopenia and Muscle. 2011;2(3):153-161.
Sikiric P, Seiwerth S, Rucman R, et al. Stable gastric pentadecapeptide BPC 157: novel therapy in gastrointestinal tract. Current Pharmaceutical Design. 2011;17(16):1612-1632.
Goldstein AL, Hannappel E, Sosne G, Kleinman HK. Thymosin beta4: a multi-functional regenerative peptide. Expert Opinion on Biological Therapy. 2012;12(1):37-51.
Pickart L, Margolina A. Regenerative and protective actions of the GHK-Cu peptide in the light of the new gene data. International Journal of Molecular Sciences. 2018;19(7):1987.
World Anti-Doping Agency. Prohibited List 2026, S1.2 and S2.