Boldenone Undecylenate (Equipoise/EQ)
A veterinary anabolic steroid (1-dehydrotestosterone) with a very long undecylenate ester, marketed for horses as Equipoise. Known for slow, lean, steady gains, marked appetite stimulation and a pronounced rise in red blood cell count. It aromatises at roughly half the rate of testosterone and is not progestogenic, giving a comparatively mild oestrogenic profile.
01 Overview
Boldenone is structurally testosterone with an added double bond at the 1,2 position, the same modification that produces methandrostenone (Dianabol) — boldenone is effectively the non-17-alpha-alkylated, injectable counterpart. The undecylenate ester is extremely long, producing a slow release over weeks and a correspondingly long detection window, which is one reason it fell out of human clinical use and persists mainly as a veterinary product.
Human data are sparse; most of what is known comes from veterinary pharmacology and athletic anecdote, hence a modest research score. Users report slow but high-quality lean-mass accrual over long cycles, strong appetite increase and elevated haematocrit that can require monitoring or blood donation. Because it aromatises less than testosterone and lacks progestogenic activity, oestrogenic side effects are usually milder, though not absent.
02 Mechanism
Androgen-receptor agonist that increases protein synthesis and erythropoiesis; the added 1,2 double bond reduces aromatisation relative to testosterone, and it does not meaningfully activate the progesterone receptor.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Common | 300–500 mg/wk | IM | Long ester; often run 14-20 weeks for full effect. |
| Heavy | 600–800 mg/wk | IM | Higher doses markedly raise haematocrit. |
Ester comparison
| Ester | Half-life | Injection freq. | Testosterone by mass |
|---|
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Slow, lean muscle gainSteady lean-mass accrual over long cycles with relatively little water retention; based largely on athletic anecdote and veterinary use. | Anecdotal | ||
| Increased appetiteFrequently reported strong appetite stimulation, useful during mass phases. | Anecdotal | ||
| Increased red blood cell countPronounced erythropoietic effect, improving endurance perception but raising haematocrit. | Preclinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Polycythaemia (high haematocrit)Boldenone is notable for strongly raising red blood cell mass, increasing blood viscosity and thrombotic risk. | Moderate | Common | Observational | |
| HPTA suppressionSuppresses endogenous testosterone and gonadotropins. | Severe | Universal | Observational | |
| Mild oestrogenic effectsSome aromatisation can cause water retention or gynaecomastia at higher doses, though less than testosterone. | Mild | Uncommon | Anecdotal |