Compound profile
Boldenone
Also known as Equipoise, EQ, Boldenone undecylenate
Last reviewed October 2026
Educational only. A summary of published research, not medical advice or a recommendation. No doses are listed.
Quick take
A long-acting veterinary injectable related to testosterone, known among users for raising appetite and red blood cell counts.
- Class
- Anabolic steroids
- Status
- Veterinary only
- Evidence
- Mostly animal & lab studies
- Half-life
- Not well documented
Mechanism fingerprint
What it acts on, and how. Each chip links to that pathway on the map.
A testosterone derivative with an extra double bond, which reduces its conversion to estradiol. Binds the androgen receptor and stimulates red blood cell production.
What makes it different
A long-acting veterinary injectable whose extra double bond reduces estrogen conversion; known for raising appetite and red blood cell counts.
Compare side by side
Mechanism & pathways
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Agonist
Androgen receptor
Receptor for testosterone and DHT. Activating it builds muscle and drives male traits such as body hair and a deeper voice. Every anabolic steroid binds it.
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Converted by
Aromatase
reduced conversion to estradiol
An enzyme that converts testosterone, and some other steroids, into estrogens such as estradiol. Steroids it works on can cause estrogen-related effects such as water retention and breast tissue growth.
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Stimulates
Red blood cell production
How the bone marrow makes red blood cells (erythropoiesis). Androgens stimulate it, which is why hematocrit is monitored during testosterone treatment.
Evidence overview
Mostly animal & lab studies
Veterinary data in horses; no controlled human trials.
A breakdown into human, animal and cell studies hasn't been added for this compound yet.
Why it's used
In horses, it improves appetite, weight and condition. Bodybuilders use it for gradual muscle gains and a bigger appetite.
Side effects & risks
Reported side effects
- Higher red blood cell count (hematocrit)
- Increased appetite
- Anxiety
- Acne
Risks and warnings
- Thicker blood from a high hematocrit raises clot and stroke risk
- Lowers HDL (“good”) cholesterol and raises LDL, adding to heart disease risk.
- Long-term use is linked to high blood pressure, heart muscle damage (cardiomyopathy), heart attacks and early death.
- Shuts down the body's own testosterone production: testicles shrink and sperm counts fall, and recovery after stopping can take months or be incomplete.
- In women: masculinizing effects (deeper voice, facial and body hair, clitoral enlargement) that can be permanent.
- Underground-lab products are often mislabeled or contaminated, and non-sterile injections can cause abscesses and infections.
- Schedule III controlled substance in the US: illegal to possess without a prescription.
- Prohibited in sport by the World Anti-Doping Agency (WADA).
FAQ
Short answers taken from this profile.
What is Boldenone?
A long-acting veterinary injectable related to testosterone, known among users for raising appetite and red blood cell counts.
How does Boldenone work?
A testosterone derivative with an extra double bond, which reduces its conversion to estradiol. Binds the androgen receptor and stimulates red blood cell production.
What receptors or pathways does Boldenone act on?
androgen receptor (agonist), aromatase (converted by; reduced conversion to estradiol) and red blood cell production (stimulates).
How is Boldenone different from similar compounds?
A long-acting veterinary injectable whose extra double bond reduces estrogen conversion; known for raising appetite and red blood cell counts.
Is Boldenone approved?
Developed and sold as a veterinary steroid for horses; not approved for use in humans.
What has Boldenone been studied for?
In horses, it improves appetite, weight and condition. Bodybuilders use it for gradual muscle gains and a bigger appetite.
How strong is the evidence?
Mostly animal & lab studies. Veterinary data in horses; no controlled human trials.
What are the main risks?
Thicker blood from a high hematocrit raises clot and stroke risk. Lowers HDL (“good”) cholesterol and raises LDL, adding to heart disease risk. Long-term use is linked to high blood pressure, heart muscle damage (cardiomyopathy), heart attacks and early death. More are listed under risks and warnings.
Sources
- Kicman AT. Pharmacology of anabolic steroids. Br J Pharmacol 2008.
- Pope HG et al. Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement. Endocr Rev 2014.