Primobolan Methenolone Stack, Effects and Reviews — Updated in 2025

Methenolone enanthate (aka Primobolan) is the active ingredient of a drug that first appeared in the 1960s, developed by German scientists. At the time, the German government invested heavily in research to help athletes better represent their country in international competitions. 

As it’s well known, the Germans are known for building things to last, and Primobolan (both oral Primo and injectable, aka Primobolan Depot) is no exception. This injectable drug has remained popular among bodybuilders and athletes to this day.

Primo Chemical Structure

Methenolone is a dihydrotestosterone derivative. It is characterized by one additional connection between carbons one and two, which helps to stabilize the 3-keto group and increase the anabolic performance of the steroid, as well as by the addition of a 1-methyl group that protects the steroid against metabolism in the liver. 

Primobolan uses methenolone with an ester of carboxylic acid (acetic acid), added to the 17-beta hydroxyl group, which protects the drug from oxidation when taken orally. Studies have shown that methenolone is an effective oral anabolic either in acetate form or in unesterified form.

Characteristics

• Anabolic activity — 88% of testosterone;
• Androgenic activity — 44% of testosterone;
• Aromatization (conversion into estrogen) — None;
• Toxicity to the liver — low (when in injectable form);
• Type — orally (pills) and injection;
• Duration— 4-6 hours (for pills), 10-14 days (for injections)
• Detection time — up to 100 days (pills), 6 months (injections)

Effects

Primo is a weak anabolic effect with minor androgenic effect:

• At a dosage of more than 500 mg a week, the anabolic effect increases several times, raising Primobolan to a level similar to some mid-level steroids;
• Methenolone enanthate is not converted into estrogen, thus avoiding the development of gynecomastia;
• Characterized by a weak rollback phenomenon;
• Minimal risk of side effects;
• The level of cholesterol and blood pressure typically remains within normal limits.

Overall, Primobolan can be considered one of the safest anabolic steroids available on the market.

Side effects

Primobolan slightly reduces the production of testosterone. Its inhibitory impact is weaker than that of testosterone or nandrolone. Research shows that a cycle of oral Primobolan at a dose of 40 mg suppresses testosterone levels by an average of 50%.

A significant reduction in the production of endogenous testosterone is usually only observed during long courses with high doses of the drug. In these cases, the use of gonadotropin is required during the cycle, otherwise testicular atrophy may develop.

Due to its low androgenic effect, Primobolan doesn’t typically cause hair loss. In most cases, methenolone causes side effects such as aggression, agitation, insomnia, and elevated liver enzymes, but only when large doses are used.

Primo Dosage and Uses

Primobolan is best suited for cutting cycles, to preserve muscle mass and improve body definition:

• The mild effect of the drug requires a long cycle (up to 8 weeks), but increasing the duration also increases the risk of side effects.
• Oral dosage of Primobolan — 50-100 mg per day. Post-cycle therapy begins 2-3 days after the course ends.
• Dosage of Primobolan depot — 400 mg, once a week. Post-cycle therapy begins 3 weeks after the last injection.

Consulting with a PRO is a must before starting a cycle to check for contraindications.

Primobolan Cycles

Given the relatively weak anabolic effect of methenolone, it is often combined with other drugs.

Primobolan and Anavar Cycle

This cycle is designed for athletes who are very concerned about their health and want to avoid side effects if possible. Note that the drug has a high price:

• Duration: 8 weeks.
• Dosage: 350-400 mg of Primobolan per week + 45 mg of oxandrolone daily.
• Effect: Around 4 kg (8 lbs) of quality muscle mass and the absence of side effects.

Primobolan and Dianabol Cycle

An interesting variation for athletes with little experience using anabolic steroids. It's for those who do not want to take more serious drugs yet and want to prepare their body for more demanding cycles.

• Duration: 6-8 weeks.
• Dosage: 450-650 mg of Primobolan per week + 35-40 mg of methandrostenolone daily.
• Effect: Progress in strength and mass with minimum side effects.

Primobolan and testosterone Cycle

This cycle is designed for experienced athletes.

• Duration: 8 weeks.
• Dosage: Primobolan (350-400 mg per week) + testosterone propionate (95 mg every other day) + trenbolone acetate (350-400 mg per week).
• Effect: Rapid increase of high-quality muscle mass with minimal fluid retention.

Conclusion

Primobolan occupies quite a unique niche in the world of anabolic steroids: 

Its primary appeal lies in its excellent safety profile, with low liver toxicity, no estrogenic side effects, and minimal impact on cholesterol and blood pressure. However, its high cost and suppressive effect on natural testosterone production are important considerations.

Ultimately, Primobolan remains a respected, though niche, choice for athletes prioritizing safety and quality gains over rapid, dramatic results.

Sources

1. The effect of an anabolic steroid, methenolone enanthate, on growth, body composition and skeletal muscle protein synthesis in the growing rat — https://www.sciencedirect.com/science/article/abs/pii/S0271531705800636 
2. The Effect of An Anabolic-Steroid, Methenolone Enanthate, On Growth, Body-Composition and Skeletal-Muscle Protein-Synthesis in the Growing Rat — https://espace.library.uq.edu.au/view/UQ:249505 
3. Whole-cell fungal-mediated structural transformation of anabolic drug metenolone acetate into potent anti-inflammatory metabolites — https://pmc.ncbi.nlm.nih.gov/articles/PMC7076145/