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Masteron vs. Primobolan

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Table of Contents

Masteron Profile

Being a dihydrotestosterone (DHT) derivative, masteron is an anabolic androgenic steroid (AAS) that does not aromatize into estrogen.  Although it was originally made only in propionate ester form, underground labs have also made it available with an enanthate ester.

Medically, it has been successfully used for various health conditions, and it has proven itself to be especially beneficial in breast cancer treatment.

In terms of bodybuilding, it is popularly stacked as part of a steroid cycle for its ability to harden the muscles and give a more vascular, dry appearance.  However, masteron is rarely used by itself, and when used as part of a stack it adds very few side effects to your existing steroid cycle.

masteron chemical structure

Fig 1. Drostanolone chemical structure

Masteron Side effects

Since it is a potent DHT derivative, masteron will increase the levels of DHT in the body more than other compounds.   An increase in DHT can result in issues with head hair follicles in men, and increasing DHT in females can cause such virilization issues as facial hair and deepening voice.

Use of Masteron

Due to its ability to bind to sex hormone binding globulin (SHBG), masteron works its magic when stacked with other steroids. This property helps increase the level of free testosterone in the body, allowing a person reach their bodybuilding goals.

Hypothetically, if you were to run masteron alone, you would likely get very little results, except for some muscle hardening; in addition, it would potentially drop your estrogen levels very low, which can hinder gains.  Therefore, bodybuilders like to stack masteron with the usual favorites like testosterone, trenbolone, and even deca durabolin because of its ability to inhibit prolactin and estrogen spikes in the body.

During contest prep, masteron is generally used towards the end of the bodybuilder's prep, to harden muscles and give a dry look.

Masteron Dosage

Masteron Propionate is usually used by the older crowd because they ignore the existence of the other ester.  However, as mentioned before, thanks to UG labs that make the enanthate available, more and more bodybuilders are using the longer ester in modern times.

Typically, a dose of 400-600 milligrams (mgs) per week is added to a stack.  If using propionate, the cycle will last 8-10 weeks and will help you dry out and harden up your muscles; on the other hand, with the longer enanthate ester, 10-12 weeks is used either towards the end or throughout.

Primobolan Profile

Primobolan (Methenolone enanthate) is a DHT based steroid that can be found in both oral and injectable forms.   Like masteron, it will not aromatize into estrogen.  Primo is usually sold in enanthate injectable form, and the oral version is not recommended because it is not 17 alpha alkylated; hence, oral primobolan is easily destroyed by the liver.   As a result, high doses need to be taken with oral primo.

Originally, primobolan was developed for bodybuilding, and it was extremely popular during the golden age of bodybuilding.  In those times, it was rumored that Arnold Schwarzenegger would inject 100mgs per day during his cycles with dbol.  Whatever the case, primobolan is still a very sought after steroid.

Another benefit of primo, that isn't well known, is the fact that it is beneficial for the immune system.  Unfortunately, this discovery came late because primobolan was never approved for medical use.  The explanation for this is fairly simple.  Most other steroids were first used in medicine, and then abused by athletes.  Primo is the opposite – it was originally developed for bodybuilding, and later other health benefits were discovered.  As a matter of fact, some of the top AIDS doctors in the world want primobolan available because of its mild side effects and immune system boosting abilities.

Schering-Primobolan Depot ampules

Fig 2. Schering Primobolan

Primobolan Side Effects

Thanks to its mild side effects, primobolan makes an excellent addition to a steroid cycle stack. However, it is important to remember that it is still a powerful hormone, so you need to respect it.  This means that it's essential to run a cycle support like N2Guard, and also have a full post cycle therapy (PCT) lined up.

Since it is a DHT derivative compound, you can expect some effects on the hairline, especially if you are prone to these.

I am not a proponent of females using DHT derivatives because of the virilization risks.   Therefore, if you're a woman and choose primobolan, make sure you take very low doses and monitor side effects closely.

Use of Primobolan

Primo does a great job of binding to SHBG, which frees up more testosterone, so it is beneficial to stack primo with other steroids to get its full effects.  A popular stack from the 70's was the 'Arnold primo stack', consisting of 700mg primo per week with 20mg dbol per day, but today a lot of guys like to stack testosterone with this cycle.

Primobolan will not put on a lot of mass or give the bodybuilder a lot of strength, and it certainly does not act fast like anadrol or trenbolone.   Instead, primo will build slow and quality gains, which are more keepable.  The user will get clean gains without the hassle of dealing with nagging side effects that come with harsher compounds.

However, keep in mind that primo is often faked and very expensive. Therefore, make sure your source has real primobolan or you will be wasting your time and money.

Primobolan Dosage

As mentioned before, in order to get the most out of it, primo should be cycled with other steroids.  Many bodybuilders will typically run it at 500-600 mgs per week for 12 weeks minimum (injectable primo), and some guys will run up to a gram per week.

For oral primobolan, you should run it at 75-100mg per day, for around 4-8 weeks.

Masteron vs. Primobolan


  • Both are DHT steroids.
  • Both do not aromatize.
  • Both have very mild side effects.
  • Both should be stacked with other steroids for maximum benefit.
  • Both are popular among those concerned with looks and not strength.
  • Both come in enanthate esters.
  • Both are pricey, with primobolan being faked quite often.


  • Primo comes in oral and injectable form, while masteron doesn't have an oral form.
  • Originally, masteron was only in propionate form, while primobolan is almost always found in enanthate form.
  • Masteron is used as a polisher and finisher to a cycle, while primo is used as part of a long term cycle.
  • Masteron was originally used medically for breast cancer, while primobolan was originally used as a pure bodybuilding steroid.
  • Masteron has gained more popularity today than in the past, while primo was very popular during the golden age.


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Steve Smi (Also known as Steve Smith), has over 12 years of experience in the bodybuilding and fitness industry. He's the co-Host of the popular Evolutionary Radio Podcast - over 500,000 listens! He has been a personal trainer and writer for the last 10 years with over 1000 articles written. He's been a moderator on forums for over 10 years. Steve holds the following certifications and records: NASM Personal Trainer NASM Fitness Nutrition Specialist Florida Local Powerlifting champion Top writer for 2019 Fitness rated

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