BMS-564929
Also known as: BMS-564929, BMS564929
The most potent SARM by weight — active in microgram amounts, and suppressive out of all proportion to the tiny dose.
Substance family
Non-steroidal compounds binding the same androgen receptor as testosterone, but favouring muscle and bone over prostate and hair. The selectivity is real; the suppression of the body's own production is not avoided by it. None is approved anywhere.
Effects on
Which outcomes this substance acts on — descriptive, not a recommendation.
Strain profile
Where this substance is most likely to hit — a rough orientation, individually dependent on dose, duration and predisposition.
This substance causes
Dosing & protocols by goal
Rough orientation ranges as reported in harm-reduction literature — not an individual treatment plan. Doses are individual and open-ended; frequency depends on the ester or half-life.
Clinical trials (dose range studied)
MedicalDose
Sub-milligram range in phase 1
Frequency
1× daily
Cycle length
Short-term
Bristol-Myers Squibb developed it for age-related functional decline. It reached phase 1 in humans; development was discontinued.
Grey market practice
Not a recommendationDose
0.5–2 mg / day reported
Frequency
1× daily
Cycle length
4–6 weeks reported
Note the unit relative to other SARMsSARMsA non-steroidal compound that binds the androgen receptor with claimed tissue selectivity.: ostarine runs at 10–25 mg, this at under 2 mg. Dosing errors here are proportionally far more consequential, and grey market liquids are difficult to measure accurately at this scale.
Side effect & countermeasure
Typical problems and what you can do to reduce harm — at a glance. Does not replace medical monitoring.
Problem
Extreme potency makes dosing errors easy
Countermeasure
Active in the sub-milligram range, roughly twenty times more potent by weight than ostarine. A measurement error that would be trivial with ostarine — a slightly overfilled pipette — is a multiple of the intended dose here. Grey market products are supplied as liquids of stated concentration, and that concentration is neither verified nor necessarily uniform.
Problem
Suppression far out of proportion to the dose
Countermeasure
This is the compound where 'selective' breaks down most clearly. At sub-milligram doses it suppresses LH, FSH and testosterone comparably to a proper steroid cycle. The small number on the label creates a false impression of mildness. PCTPCTThe protocol after a cycle intended to restart the body's own testosterone production. with enclomiphene or clomiphene, bloodwork before and after.
Problem
Severe effect on lipids
Countermeasure
HDLHDLThe lipoprotein that carries cholesterol away from artery walls — suppressed hard by oral steroids. suppressionsuppressionThe body shutting down its own testosterone production because an external source is present. is reported as pronounced. Cardio, omega-3 and citrus bergamot help at the margin; a full lipid panel is what decides whether to continue.
Problem
Development was discontinued after phase 1
Countermeasure
Bristol-Myers Squibb did not take it further. The public record does not fully explain why, which is itself worth weighing — a pharmaceutical company abandoning a compound after first-in-human testing is not usually a sign that everything looked good.
Overview
BMS-564929 is the most potent SARM in circulation by weight, and that fact is the whole story of the compound.
Bristol-Myers Squibb developed it for age-related functional decline and took it into phase 1 human testing — putting it among the small group of SARMs given to people under supervision. It did not go further.
Mechanism of Action
A non-steroidal androgen receptor agonist with very high binding affinity and strong tissue selectivity for muscle over prostate in preclinical models. The selectivity profile was genuinely impressive on paper, which is why a large company pursued it.
The potency is the distinguishing feature: it is active in the sub-milligram range, roughly twenty times more potent per milligram than ostarine.
Why Potency Is a Risk Rather Than a Feature
High potency sounds like an advantage, and in a manufactured pharmaceutical with verified content and accurate tablets, it would be neutral.
In the grey market it is the opposite. The compound arrives as a liquid with a stated concentration that nobody has verified. Dosing happens with a dropper or pipette. At 20 mg of ostarine, being off by a few tenths of a millilitre changes little. At 1 mg of BMS-564929, the same measurement error can double the dose.
The second problem is perception. A number like "1 mg" reads as gentle next to "20 mg", and people repeatedly assume a small figure means a small effect. It does not — it means the molecule is more active per unit weight. The suppression at these doses is comparable to a steroid cycle, and users are frequently surprised by how hard recovery is after what seemed like a trivial amount.
Where It Sits
Among SARMs it belongs with S-23 at the strong, heavily suppressive end rather than with ostarine. It has the additional distinction of having been in a human trial, which most of this category has not — but a phase 1 that did not continue tells you little except that the company stopped.
Side Effects & Risks
- Strong suppression of the body's own production, disproportionate to the dose size
- Severe HDL suppression, rising LDL
- Elevated liver values reported
- Fatigue, low mood and low libido during and after
- Dosing accuracy problems inherent to sub-milligram amounts in unverified liquids
- No manufacturing oversight
Blood Work & Monitoring
- Total and free testosterone, LH, FSH — before, during and after; expect substantial suppression
- Lipid profile (LDL, HDL, ApoB)
- Liver values (ALT, AST, GGT)
- Estradiol (sensitive assay) — falls with suppressed testosterone
Legal status by region
Regulation differs considerably between jurisdictions and changes over time. This is a rough orientation, not legal advice — check the rules that apply where you are.
| Region | Regulatory status |
|---|---|
| United States | Not approved; FDA warning applies to the SARM category |
| EU / UK | No marketing authorisation |
| Most other jurisdictions | Unregulated grey area |
| Competitive sport | Prohibited at all timesListed by WADA under S1.2. |