Is Clenbuterol legal in the United Kingdom?

The first randomised trial in humans, published in 2025, found clenbuterol added 0.91 kg of lean mass in two weeks, changed fat mass not at all, and cut maximal oxygen uptake by 7 percent. It is not approved for human use in the United States, and it has caused documented poisoning outbreaks from contaminated meat and from adulterated heroin.

Clenbuterol is a long-acting beta-2 adrenergic agonist. It is a licensed human bronchodilator in a handful of countries, a veterinary bronchodilator elsewhere, and in the United States it is neither: there is no FDA approval for human use, and the American product is a horse medicine.

Mechanism: Selective beta-2 adrenergic receptor agonism. In skeletal muscle the receptor couples to cyclic AMP and protein kinase A, which in the 2025 human trial was markedly activated along with phosphorylation of ribosomal protein S6, the anabolic signal that drove the lean mass gain.

Regulatory history: Not approved for human use in the United States at any dose or indication. The only US approval is veterinary, as a bronchodilator for horses. It is a licensed human bronchodilator in some other countries. Prohibited in sport by WADA as an anabolic agent.

Licenses medicines for the UK market. A compound without a marketing authorisation is an unlicensed medicine, which can only lawfully be supplied for human use through a prescriber under the specials scheme, not sold as a research product.

The classification above is the The Longevity Archive reading of Medicines and Healthcare products Regulatory Agency listings for Clenbuterol at the reviewed date, not a legal opinion. Rules change, and importing, prescribing and possessing a compound can each be treated differently. Check the regulator directly before acting on anything here.