Boldenone
Boldenone is a synthetic anabolic steroid approved in the US only as a veterinary medicine for debilitated horses. It has never been approved as a medicine for people.
Reference information, not medical advice. Enhanced Training Studio doesn't sell, supply or recommend any substance. Doses are left out on purpose: only a prescriber can set one. How this library is written.
What it is
Boldenone is a synthetic anabolic–androgenic steroid. As boldenone undecylenate (brand name Equipoise), it is a veterinary medicine approved in the US for horses [1, 2]. It has never been approved for use in people, and the US Drug Enforcement Administration describes it as used only in veterinary medicine [3]. It is a Schedule III controlled substance in the US and a Class C drug in the UK [4, 5].
How it works
Boldenone acts on the androgen receptor, like testosterone. Chemically it is very close to testosterone, differing by one extra double bond in the steroid ring [4]. The undecylenate form is an ester given by injection in horses [1, 2].
Approved medical uses
None in people.
In the US, boldenone undecylenate is approved as an aid for treating debilitated horses when an improvement in weight, hair coat or general physical condition is desired [1, 2]. It may only be used by or on the order of a licensed veterinarian, and must not be given to horses intended for human consumption [1]. In the EU, giving substances with androgenic action to farm animals for growth is prohibited [6].
What the research shows
- No clinical trials in people. Boldenone has never been studied as a medicine in humans, so there is no controlled human evidence on its benefits or safety [1, 3].
- Human data come from non-medical use. What is known in people comes from observational studies and reports of anabolic steroid users, who usually take several steroids together at supraphysiological doses. This makes it hard to link harms to boldenone alone [7].
- Animal studies. In a study in rats, boldenone undecylenate injections raised markers of liver and kidney damage and caused oxidative stress and tissue changes [8]. These findings are from animals and have not been confirmed in people.
- Risks of the class. Non-medical anabolic steroid use is linked to an increased risk of death and to heart, mental health, hormonal, liver and kidney problems [7].
Known risks and side effects
Specific human data on boldenone are scarce. The risks below are reported for anabolic steroids as a class, or from animal studies where stated.
- Heart and blood vessels: heart attack, stroke, high blood pressure and deep vein thrombosis [9]; cardiovascular disease and increased risk of death with non-medical use [7].
- Liver and kidneys: liver or kidney problems, including failure, in people [9]; liver and kidney damage in rats [8].
- Hormones and fertility in men: reduced sperm count, infertility, shrunken testicles, erectile dysfunction and breast development [9].
- Effects in women: facial and body hair growth, deepened voice, reduced breast size and enlargement of the clitoris [9].
- Mental health: aggression, mood swings and paranoia; dependence, with depression, anxiety and insomnia on stopping [9].
- Infections: hepatitis B, hepatitis C and HIV from shared needles [9].
- Sport: boldenone is prohibited at all times under the World Anti-Doping Agency (WADA) Prohibited List [10].
Blood tests commonly monitored
There are no official monitoring guidelines for boldenone, because it is not approved for use in people. For testosterone, the closest approved medicine in this class, the Endocrine Society guideline recommends monitoring [11]:
- Testosterone level during treatment [11].
- Haematocrit (the proportion of red blood cells), with treatment withheld if it rises above 54% [11].
- PSA (prostate-specific antigen) in men, with urology referral for a confirmed rise [11].
Anyone who has used boldenone should talk to a doctor about appropriate tests.
If you and your doctor are monitoring treatment, Enhanced Training Studio keeps a private log on your phone: what you take and when, your blood test results over time, and how you feel. How tracking works.
Sources
- US Code of Federal Regulations. 21 CFR 522.204, Boldenone. Legal Information Institute, Cornell Law School, accessed 2026. LII
- US Food and Drug Administration. Implantation or Injectable Dosage Form New Animal Drugs; Boldenone. Federal Register, 2005. Federal Register
- US Drug Enforcement Administration, Diversion Control Division. Anabolic Steroids (drug and chemical information). DEA, 2025. DEA
- US Code of Federal Regulations. 21 CFR 1308.13, Schedule III. Legal Information Institute, Cornell Law School, accessed 2026. LII
- Home Office. List of most commonly encountered drugs currently controlled under the misuse of drugs legislation. GOV.UK, 2025. GOV.UK
- Council of the European Union. Council Directive 96/22/EC concerning the prohibition on the use in stockfarming of certain substances having a hormonal or thyrostatic action and of beta-agonists. EUR-Lex, 1996 (consolidated 2008). EUR-Lex
- Pope HG Jr, Wood RI, Rogol A, Nyberg F, Bowers L, Bhasin S. Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement. Endocrine Reviews, 2014. Endocrine Society
- Behairy, Mohamed, Ebraheim, et al. Boldenone undecylenate-mediated hepatorenal impairment by oxidative damage and dysregulation of heat shock protein 90 and androgen receptors expressions: vitamin C preventive role. Frontiers in Pharmacology, 2021. Frontiers
- NHS. Anabolic steroid misuse. NHS website, 2026. NHS
- World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026. WADA, 2025. WADA
- Bhasin S, Brito JP, Cunningham GR, et al. Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology and Metabolism, 2018. Endocrine Society
Related
Last reviewed 7 October 2026. General information, not medical advice. Found a mistake? Email [email protected].