In the world of anabolic steroids, Boldenone Undecylenate—more commonly known as Equipoise—has earned a reputation for delivering steady, sustainable lean muscle gains with fewer androgenic side effects compared to faster-acting injectables like Testosterone Enanthate or potent compounds such as Trenbolone.
While its origins lie in veterinary medicine, Equipoise has become a point of discussion in bodybuilding circles for its ability to enhance red blood cell production, appetite, and muscle endurance. But it remains unapproved for human use and is banned in competitive sports, making it essential to understand both its benefits and risks before considering its role in a cycle.
In this guide, we’ll break down Equipoise’s history, mechanism of action, benefits, side effects, and compare it with other popular anabolic steroids such as Anavar, Masteron (Drostanolone), and Primobolan.
History & Development
→ Origins in Veterinary Medicine
Boldenone Undecylenate was first synthesized in the 1950s by Ciba Pharmaceuticals. Initially explored for human medical applications, it was soon redirected for veterinary use due to its favorable anabolic-to-androgenic ratio in animals. Under the trade name Equipoise, it became a staple in equine medicine, valued for its ability to:
“Boldenone was originally synthesized for humans but transitioned quickly to veterinary use due to a better anabolic-to-androgenic ratio for animals.” — William Llewellyn, Anabolics
→ Adoption in Bodybuilding (1970s)
By the late 1970s, word spread in bodybuilding communities about Equipoise’s steady gains and milder androgenic profile compared to stronger compounds. Athletes appreciated its:
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Long-acting undecylenate ester, allowing less frequent injections
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Lower aromatization rate than testosterone, reducing estrogen-related side effects
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Lean mass gains without the dramatic bulk-and-crash cycle of some bulking steroids
→ Current Legal & Sporting Status
Equipoise remains FDA-unapproved for human use and is classified solely as a veterinary medication in most countries. Its use in competitive sports is prohibited under the World Anti-Doping Agency (WADA) Prohibited List.
“There is no therapeutic or medical use for boldenone in humans; it is not FDA-approved for any human indication.” — USADA, Spirit of Sport
Mechanism of Action
Equipoise (Boldenone Undecylenate) is a derivative of testosterone with a double bond between carbons 1 and 2, which significantly alters its anabolic and androgenic behavior. This structural modification:
→ Increases Anabolic Activity
Equipoise binds to androgen receptors in skeletal muscle tissue, stimulating protein synthesis and nitrogen retention—key drivers of muscle growth.
→ Reduces Androgenic Potency
Compared to Testosterone Enanthate, boldenone exhibits a milder androgenic profile, leading to fewer side effects like hair loss or acne for some users.
→ Enhances Erythropoiesis
By boosting red blood cell production, Equipoise improves oxygen transport, potentially enhancing endurance and recovery between intense training sessions.
→ Slower Release & Longer Half-Life
The undecylenate ester slows absorption from the injection site, providing stable blood concentrations and less frequent dosing compared to shorter esters like testosterone propionate.
“The addition of the 1,2 double bond in boldenone significantly changes its interaction with 5α-reductase and aromatase enzymes, leading to reduced androgenic and estrogenic conversion.” — Llewellyn, Anabolics
Performance Benefits of Equipoise
While Equipoise is not FDA-approved for human use, its anabolic properties have led to its use among bodybuilders seeking specific training outcomes. Potential performance-related benefits include:
→ Lean, Quality Muscle Gains
Equipoise tends to promote gradual, steady muscle growth rather than rapid mass accumulation, making it a favorite for athletes wanting lean tissue without significant fat or water gain. This is often compared to compounds like Primobolan for “clean” bulk cycles.
→ Increased Endurance
Enhanced red blood cell production can improve oxygen delivery to muscles, potentially delaying fatigue during high-intensity or long-duration training.
→ Improved Recovery Rates
By increasing protein synthesis and nitrogen retention, Equipoise may shorten recovery time between heavy training sessions, similar to what athletes report with Anavar.
→ Milder Side Effect Profile
Compared to stronger injectables like Trenbolone, Equipoise generally has a lower incidence of severe androgenic effects, though it still carries risks.
“Athletes often choose boldenone for its favorable balance of anabolic and androgenic effects, making it versatile for both bulking and cutting phases.” — Kicman, Journal of Steroid Biochemistry and Molecular Biology
Side Effects & Risks
Despite its milder androgenic profile, Equipoise still carries significant risks—both short-term and long-term—especially since it’s not approved for human use.
→ Androgenic Effects
Possible issues include acne, oily skin, and accelerated male-pattern baldness in genetically predisposed individuals. While less pronounced than with Trenbolone or Masteron (Drostanolone), these effects can still occur.
→ Estrogenic Effects
Although boldenone aromatizes at about 50% the rate of Testosterone Enanthate, excess estrogen can still lead to water retention, bloating, and gynecomastia in susceptible users.
→ Cardiovascular Strain
Equipoise can negatively impact cholesterol levels—lowering HDL (“good” cholesterol) and raising LDL (“bad” cholesterol)—increasing cardiovascular risk over time.
→ Suppression of Natural Testosterone
Like all anabolic steroids, Equipoise suppresses endogenous testosterone production, making a proper PCT stack critical after discontinuation.
“Even with a favorable anabolic-to-androgenic ratio, boldenone use can lead to long-term endocrine disruption and cardiovascular changes.” — Kicman, Journal of Steroid Biochemistry and Molecular Biology
Dosage & Cycle Structure
Equipoise’s undecylenate ester gives it a long half-life (up to 14 days), which allows for less frequent injections but also means it takes several weeks to reach peak levels.
→ Typical Dosage (Bodybuilding Use)
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Men: 300–600 mg per week
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Women: Rarely used due to virilization risk; if attempted, typically 50–75 mg per week
→ Cycle Length
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Commonly run for 12–16 weeks due to its slow buildup and gradual effects
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Often stacked with a base testosterone (e.g., Testosterone Enanthate) to maintain hormonal balance
→ Popular Stacks
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Bulking: Equipoise + Testosterone Enanthate + Anavar for lean mass
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Cutting: Equipoise + Testosterone Propionate + Masteron (Drostanolone) for hardness and definition
Comparison to Other Steroids
→ Equipoise vs. Testosterone Enanthate
Both are long-ester injectables, but testosterone generally provides faster strength gains with more water retention, while Equipoise is slower-acting and produces leaner tissue.
→ Equipoise vs. Primobolan
Primobolan is considered even milder and less estrogenic but is often more expensive and provides less dramatic gains.
→ Equipoise vs. Trenbolone
Trenbolone delivers rapid size and strength increases but with a much higher risk of side effects—Equipoise is more forgiving but slower to produce results.
→ Equipoise vs. Anavar
Anavar is an oral steroid favored for cutting phases and female use, whereas Equipoise is injectable and better suited for long, slow lean-bulk cycles.
Legal Status of Equipoise
Equipoise (Boldenone Undecylenate) is classified as a Schedule III controlled substance in the United States under the Anabolic Steroid Control Act, making it illegal to possess, sell, or use without a prescription—something not issued for humans in the U.S.
→ Veterinary Use Only
In the U.S., Equipoise is approved exclusively for veterinary use in horses. It is not prescribed or manufactured for human consumption.
→ International Regulations
Many countries follow similar restrictions, with possession without veterinary documentation considered a criminal offense. Penalties vary by jurisdiction, but often include fines and possible imprisonment.
→ Banned in Sport
The World Anti-Doping Agency (WADA) lists boldenone as prohibited at all times, meaning athletes face suspensions, disqualification, and loss of titles if caught using it.
“Boldenone and its esters are prohibited at all times under the WADA Prohibited List, with no threshold allowance for detection.” — WADA, Prohibited List
PCT (Post-Cycle Therapy) Recommendations
Because Equipoise significantly suppresses natural testosterone production, running a proper Post-Cycle Therapy (PCT) is critical to restore hormonal balance.
→ Common PCT Agents
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Clomid: Stimulates natural testosterone production through selective estrogen receptor modulation.
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Nolvadex: Helps block estrogen receptors and supports hormonal recovery.
→ Typical PCT Protocol for Equipoise
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Start 2–3 weeks after last injection due to its long ester
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Run Clomid 50 mg/day + Nolvadex 40 mg/day for 2 weeks, then taper for an additional 2–4 weeks
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Include natural testosterone support supplements like ZMT and DHEA for added recovery assistance
Conclusion About EQ!
Equipoise offers a unique anabolic profile—steady lean muscle gains, improved endurance, and a relatively mild side effect profile compared to more aggressive injectables like Trenbolone. However, its slow-acting nature, veterinary-only approval, and illegality for human use make it a compound that carries serious legal, ethical, and health considerations.
If included in a bodybuilding cycle, Equipoise is often paired with a base testosterone and supported by a carefully structured PCT to avoid long-term hormonal suppression. For those seeking alternatives with fewer legal and health risks, compounds like Primobolan or Anavar may be considered—though these too require an informed, cautious approach.
