Is MK-677 legal in the UK? Legal status of research compounds

Last reviewed: 27 September 2026. This page describes the regulatory position in the United Kingdom of MK-677 (ibutamoren) and of the SARMs and related research compounds named below, all of which we stock. It is general information, not legal advice, and nothing on it is guidance for human use.

Short answer

MK-677 is not listed as a controlled drug under the Misuse of Drugs Act 1971, so buying or possessing it is not in itself an offence under that Act. It is not a licensed medicine, and Free Muscle does not sell it as a food supplement. Free Muscle supplies it for laboratory research use only, to customers aged 18 or over. It is not for human consumption.

What the law says

  • Misuse of Drugs Act 1971. Schedule 2 does not name MK-677 (ibutamoren), the non-steroidal SARMs RAD-140, LGD-4033, ostarine, andarine and S-23, Cardarine (GW-501516) or SR9009. We checked the revised text on legislation.gov.uk, together with the 2024 amendment orders and the 2026 temporary class drug order, on 27 September 2026. YK-11 is different: it has a steroidal structure, and Part III of Schedule 2 also controls some steroids by a general structural definition rather than by name. We have not obtained a legal opinion on whether that definition covers YK-11, so we make no statement either way about its status under the Act.
  • Human Medicines Regulations 2012. A medicinal product is any substance presented as having properties of preventing or treating disease in human beings, or any substance that may be used by or administered to human beings with a view to restoring, correcting or modifying a physiological function by exerting a pharmacological, immunological or metabolic action, or to making a medical diagnosis (regulation 2(1)). Selling or supplying, or offering to sell or supply, an unauthorised medicinal product is prohibited (regulation 46), and so is publishing an advertisement in Great Britain for a medicinal product without an authorisation (regulation 279). No UK marketing authorisation exists for MK-677 or for any of the other compounds named on this page.
  • Sport. The World Anti-Doping Agency's 2026 Prohibited List names ibutamoren (MK-677) under S2 as a growth hormone secretagogue; RAD140, YK-11, LGD-4033 (ligandrol), enobosarm (ostarine), andarine and S-23 under S1.2 as selective androgen receptor modulators; and GW501516 (Cardarine) and SR9009 under S4 as metabolic modulators. All three classes are prohibited at all times, in and out of competition.

Which of these compounds are SARMs

RAD-140, LGD-4033, ostarine, andarine, S-23 and YK-11 are selective androgen receptor modulators (SARMs), and YK-11 is the only one of them with a steroidal structure. MK-677 is not a SARM: it is a growth hormone secretagogue. Cardarine (GW-501516) is a PPAR-delta agonist and SR9009 is a Rev-erb agonist. Neither is a SARM.

What this means when you order from Free Muscle

  • Research compounds are sold for laboratory research use only, to buyers aged 18 or over, and not for human consumption.
  • Every batch of a Free Muscle-brand compound, including our own MK-677, is assayed for identity and purity by Janoshik Analytical, an independent laboratory. For other brands in the Muscle Market, a certificate is available only where the manufacturer supplies one for the batch we hold. Email the batch number on your pack to freemuscleuk@gmail.com and we send the certificate for that batch where one exists.
  • UK orders ship free and tracked, in plain packaging. Unopened items can be returned within 30 days of delivery.
  • If your order is going outside the UK, you must check before you order that you may lawfully import the product into your country.

Sources

  • Misuse of Drugs Act 1971, Schedule 2 (revised text on legislation.gov.uk); Misuse of Drugs Act 1971 (Amendment) Order 2024 (SI 2024/190); Misuse of Drugs Act 1971 (Amendment) (No. 2) Order 2024 (SI 2024/1361); Misuse of Drugs Act 1971 (Temporary Class Drug) Order 2026 (SI 2026/613).
  • Human Medicines Regulations 2012 (SI 2012/1916), regulations 2, 46 and 279.
  • World Anti-Doping Agency, 2026 Prohibited List, sections S1, S2 and S4.

Related

Research compounds sold by Free Muscle are supplied for laboratory research use only. They are not for human consumption, are not licensed medicines or food supplements, and have not been evaluated by the MHRA, EMA or FDA. Sold to adults aged 18 or over. Nothing on this page is legal, medical or dosing advice.