Head to head
Clenbuterol against Enobosarm
Two non-steroidal routes to lean mass, both unapproved for human use in the United States. The first randomised human trial of clenbuterol, published in 2025, added 0.91 kg of lean mass in two weeks, changed fat mass not at all, and cut maximal oxygen uptake by 7 percent.
Column A
ClenbuterolClenbuterol hydrochloride, selective beta-2 adrenergic agonist
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.
Column B
EnobosarmEnobosarm (ostarine, GTx-024, MK-2866)
The selective androgen receptor modulator known on the gray market as ostarine, now in formal trials where 3 mg cut lean-mass loss on semaglutide by 71% in adults over 60.
Side by side, on the facts we can check
| Attribute | Clenbuterol | Enobosarm |
|---|---|---|
| Category | Muscle & Performance | Muscle & Performance |
| FDA status | 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. | Investigational; not approved for any use. Unapproved SARM products are illegal to sell as supplements. |
| Half-life | About 35 hours in plasma in healthy volunteers, which is long for a beta-2 agonist and is why effects and detection both persist for days. | ~24 hours (once-daily oral) |
| Molecular weight | 277.2 Da as the free base; the hydrochloride salt used in products is 313.7 Da | 389.3 Da |
| 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. The same receptor class in the heart and vasculature produces the tachycardia, tremor and hypokalaemia that define the poisoning syndrome. Repeated dosing desensitises the receptor: the signalling response in that trial declined across the two weeks, which is the pharmacological basis of the cycling practice users have arrived at empirically. | Tissue-selective androgen receptor agonism that promotes muscle protein synthesis with less androgenic effect on prostate and skin than testosterone. |
| Human studies cited | 6 | 3 |
| Legal status, US | Not approved for human use; veterinary drug only | Investigational; SARMs are not legal dietary ingredients and are on the WADA prohibited list |
Frequently asked questions
What is the difference between Clenbuterol and Enobosarm?
Clenbuterol: 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. Enobosarm: The selective androgen receptor modulator known on the gray market as ostarine, now in formal trials where 3 mg cut lean-mass loss on semaglutide by 71% in adults over 60.
Which has stronger research evidence, Clenbuterol or Enobosarm?
This database does not grade compounds. It counts what was run in people: 6 of the 7 studies cited on the Clenbuterol profile were human work, against 3 of 3 for Enobosarm. Those counts are of our own citation lists and understate any larger literature, and neither is a recommendation.
Are Clenbuterol and Enobosarm FDA-approved?
Clenbuterol: 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.. Enobosarm: Investigational; not approved for any use. Unapproved SARM products are illegal to sell as supplements..
Reviewed Sep 2026. This page sets two published records side by side. It is educational, it is not medical advice, and it contains no dosing protocols or recommendations for personal use.