SARMs 101: the research, the law and how to choose
Last reviewed 15 September 2026. Products are supplied strictly for laboratory research and are not for human consumption. 18+ only. This guide summarises published research; it is not medical advice.
What SARMs are
Selective androgen receptor modulators are a class of synthetic compounds developed from the late 1990s, first at the University of Tennessee and later by pharmaceutical companies including GTx, Ligand and Merck. They bind to the androgen receptor, the same receptor that testosterone acts on, but were designed to act selectively in muscle and bone tissue rather than across the whole body. That selectivity was the research goal: a treatment for muscle wasting and bone loss without the full range of effects of anabolic steroids. No SARM has been approved as a medicine anywhere in the world.
What the trials found
Ostarine (MK-2866, enobosarm) is the most studied compound. It reached phase III trials for cancer-related muscle wasting (the POWER trials, 2013) and phase II trials in breast cancer, and the published data include measured changes in lean mass, along with reported effects on lipids and liver enzymes. Ligandrol (LGD-4033) has one published phase I study in healthy men (Basaria et al., 2013). Testolone (RAD-140) has preclinical data and one terminated phase I study in breast cancer. Ibutamoren (MK-677) is not a SARM but a growth hormone secretagogue with two-year clinical data in older adults (Nass et al., 2008). Cardarine (GW-501516) is a PPAR delta agonist whose development was stopped in 2007 after animal studies found tumours; that finding is the reason it is discussed so carefully. Stenabolic (SR-9009), Andarine (S-4), YK-11, S-23 and ACP-105 have animal or in-vitro data only.
The UK legal position in 2026
SARMs are not controlled drugs under the Misuse of Drugs Act 1971 and are not listed as anabolic steroids. They are not licensed medicines, which means they cannot lawfully be sold for human consumption; the MHRA treats any product sold with dosing instructions or health claims as an unlicensed medicine. They may be sold as research chemicals. In sport, every SARM is on the WADA prohibited list under S1.2 (other anabolic agents), and MK-677 under S2, so any tested athlete faces a ban. Buyers outside the UK must check their own country's rules; several EU countries and Australia treat SARMs as prescription-only or prohibited. Full guide: Are SARMs legal in the UK?
How to read a certificate of analysis
A certificate of analysis is a lab report for a specific batch. Look for the lab name and accreditation (UKAS or ISO 17025), the batch number matching the bottle, the method (HPLC or LC-MS for identity and purity), the purity figure and the test date. A certificate without a batch number, or one older than the product, is not evidence of anything. Every batch is independently tested and its certificate of analysis is published on the product page and the Lab Testing page. Full guide: Reading a certificate of analysis.
The compounds compared
| Compound | What the research studied | Highest trial stage | Guide |
|---|---|---|---|
| Ostarine (MK-2866) | Lean mass and bone | Phase III | Guide |
| Ligandrol (LGD-4033) | Lean mass | Phase I | Guide |
| Testolone (RAD-140) | Breast cancer and muscle | Phase I (terminated) | Guide |
| Ibutamoren (MK-677) | Growth hormone and lean mass | Phase II | Guide |
| Cardarine (GW-501516) | Endurance and lipids | Stopped 2007 (animal safety) | Guide |
| Stenabolic (SR-9009) | Circadian and metabolic | Preclinical | Guide |
| Andarine (S-4) | Muscle and bone | Preclinical | Guide |
| YK-11 | Myostatin pathway | In vitro | Range |
| S-23 | Contraception research | Preclinical | Range |
| ACP-105 | Androgen receptor | Preclinical | Range |
How researchers choose
Start with the compound with the most published human data (Ostarine), read the safety findings for each compound before anything else, check the specification per capsule and the batch number, and keep the certificate for your records when it is published.
Shop the research range Read all guides
Peptides: the other half of the range
Since September 2026 SARMs Store also stocks the Origin Peptides range, 27 lyophilised peptides in five series. They are a different class from SARMs: short amino acid chains with their own receptors, mostly rodent-stage evidence, and cold-chain storage. The groups researchers ask about most are tissue repair (BPC-157, TB-500, Wolverine blend), growth hormone secretagogue peptides (CJC-1295 with Ipamorelin, Sermorelin), metabolic and ageing models (NAD+, 5-Amino-1MQ) and skin (GHK-Cu, GLOW blend). Start with SARMs vs peptides for the mechanism, evidence and storage differences.
Products are supplied strictly for laboratory research and are not for human consumption. 18+ only.