Boldenone
Equipoise (boldenone undecylenate); veterinary AAS
Evidence grade 2 of 5, Thin. Read how the Atlas grades evidence.
The written rationale for this grade is still being prepared.
- FDA
- No human approval; approved as a veterinary drug (Schedule III as an anabolic steroid)
- WADA
- Prohibited at all times (S1 Anabolic Agents); a frequent long-window anti-doping finding.
Reference only. Not medical advice.
This is something to take to a clinician. The Atlas can tell you what is known about boldenone in general. It cannot tell you what is happening in your body, and the difference matters most for exactly the symptoms that bring people to this page.
Boldenone is a testosterone derivative (a 1-dehydro analog, structurally related to the Dianabol parent) marketed as the long-acting undecylenate ester Equipoise for veterinary use in horses. It has no human medical approval. It aromatizes to estrogen at a low-to-moderate rate, strongly stimulates erythropoiesis (notable polycythemia risk), and has an exceptionally long detection window. Human safety data are essentially nonexistent; harm assessment relies on the general AAS class profile.
A horse drug repurposed for physique use, slow, long-detecting, and unstudied in humans.
What people take it for
These are the reasons people give for taking it. They are not effects it has been shown to have.
- No approved human indication
- Boldenone is a veterinary drug. No FDA human approval exists.
How it is supposed to work
Boldenone binds the androgen receptor to drive protein synthesis and red-cell production. It aromatizes to estradiol to a modest degree, so estrogenic effects are possible. Its pronounced effect on erythropoiesis raises hematocrit and blood viscosity.
Differs from testosterone by a double bond between carbons 1 and 2 (the same modification that distinguishes Dianabol from testosterone, but without 17-alpha-alkylation). The undecylenate ester gives slow release and a very long half-life.
The polycythemia and detection catch
Boldenone's strong erythropoietic drive can push hematocrit into ranges associated with thrombotic risk, while its long ester means suppression and a positive anti-doping test can persist for many months after the last dose, long after the user believes it has cleared.
Safety in detail
This intervention involves significant physiological effects and requires evaluation and monitoring by a qualified physician. Boldenone has no approved human use; self-administration carries documented health risks.
- Marked polycythemia/elevated hematocrit with thrombotic risk.
- Estrogenic effects possible via aromatization.
- HPTA suppression with a very long ester tail.
- Adverse lipid/cardiovascular profile shared with the class.
- No human safety data; counterfeit/veterinary-source contamination risk.
Replacement is not the same as a cycle
No human therapeutic dose exists; all human use is supraphysiological and unsanctioned. This entry provides no dosing or cycle information.
What it does to fertility
Suppresses LH/FSH and spermatogenesis like other AAS; the long ester prolongs suppression and impaired fertility after discontinuation.
What has to be monitored
The bloodwork this needs, and the reason it belongs with a clinician rather than a website.
- Hematocrit/hemoglobin
- Lipid panel
- Blood pressure
- Estradiol
- LH/FSH, testosterone
What people get wrong
Often said'Equipoise is a mild, clean steroid'
Actually'Mild' subjective reports ignore strong polycythemia risk, estrogenic potential and a months-long suppression and detection window; there are no human safety studies to support a 'clean' claim.
Who profits, and who pushes back
Nobody is named here yet, because we have not done that work on this entry. Read that as unfinished. Somebody almost certainly sells this, and somebody almost certainly disputes it. Assume both until we have checked.
How we got here
Boldenone was synthesized in the mid-20th century and developed for veterinary use; Equipoise (boldenone undecylenate) became a standard equine anabolic. It crossed into human illicit physique use without ever gaining human medical approval.
- 1940s-50sBoldenone synthesized
- Mid-20th c.Developed for veterinary (equine) use as Equipoise
- PresentIllicit physique use; no human approval
At a glance
- Class
- Testosterone 1-dehydro derivative
- Form
- Undecylenate ester (long-acting)
- Human approval
- None (veterinary only)
- Notable effect
- Strong erythropoietic stimulation
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about Boldenone. A short entry is not a safe entry.
- Cost and market. We have not documented what it sells for or who sells it.
- Supply chain. We have not mapped where it is made.
- Who uses it. We have not documented the user groups.
- What could change. No forward-looking summary yet.
- How it compares. We have not set it against the alternatives.
- Children and teenagers. We have not checked what is known about younger people.
- What can go wrong. We have not written the risk line for this one. Read the safety section below rather than treating its absence as reassurance.
- Where we land. We have not taken a position on this yet.
Sources
The studies below are named and described, but not linked. You cannot open them from here and check our reading against them, which means this page is our summary of the literature rather than a document you can verify. Weigh it accordingly until the links exist.
The studies that matter
Veterinary pharmacology/anti-doping literature on boldenone undecylenatevarious
Documents long detection window and erythropoietic effect; human therapeutic data are absent.
Pope et al., Endocrine Society Scientific Statement2014
General AAS cardiovascular/hematologic harm framework applied in lieu of boldenone-specific human data.