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Testosterone esters

At some point of time, all of us have seen the 'gurus' on the fitness forums chiming into every testosterone thread with the cliche'd response of "test is test," and "it doesn't matter which ester you use."  However, the reality is that the testosterone ester you decide to use on your cycle will determine how often you have to inject, how painful the injection is, the timing of blood work, and even the chances of you getting busted if you are a tested athlete.  Therefore, not all testosterone esters are the same, and you should not treat them the same, unless you view cycling steroids like throwing darts at a wall blindfolded.  In this article we will explain what half life is, what esters are, and what each testosterone ester is all about.

cypionate vs enanthate ester comparison

Fig 1. Cypionate vs. Enanthate comparison

Table of Contents

Understanding half lives

Many newbies to the steroid world do not understand what the concept of half life really means.  In fact, many just think that if a compound has a 10 day half life, then after 10 days the steroid ester is out of the body overnight.  Consequently, in their mind the steroid is active on day 9, but on day 10 you wake up, and magically its out of your system!  Obviously, this is not the way it works, and let me explain what I mean.

Every drug out there has a half life, whether it's an aspirin, an oral steroid, or an injectable steroid like testosterone.  Therefore, you need to know 3 things in order to understand how long a particular compound will be in your system.

  1.  How long you have been running it:  Running a compound for a moderate amount of time with multiple doses is different to just injecting a steroid once, or twice, and then stopping.
  2.  The half life duration of the compound:  Something that has a half life of 4 hours will stay in your system for less time than something that has a 10 day half life.
  3.  Dosages used:  If you run a tiny amount of the drug, then obviously there will be less active substance in your system when compared to a situation where larger dosages were used.

Calculating the half life

So based on the above, lets say for example you ran Testosterone Enanthate at 500 milligrams (mg) per week with a split dosage for 10 or 12 weeks, and it has a 10 day half life.  Thus, once you stop injecting it, after 10 days only half of the remaining esters will be left in your system, then after another 10 days half of that will be left, and so on.  The point is that after 10 days it doesn't just go to 0 overnight.  Hence, in simplified terms, out of the 500 mgs you will only have 250 left after 10 days, then after another ten days you will only have half of that left – 125 mgs, and the process will continue until there is no active substance left in the system.  By knowing this you can make an approximation of how long an ester will linger by multiplying it by 5, so a 10 day half life would take 50 days to be out of your system, give or take a few days.

What are esters?

Esters are chains of carbon and hydrogen atoms, which are attached to the parent steroid hormone, usually at the 17th carbon position.  The longer the ester chain, the longer it will take for the full dosage to reach complete circulation, and vice versa.  As a result, the beauty of esters releasing slowly is that you don't have to inject your steroids every 4 hours, and you can get away with injecting once a week or less, depending on the particular ester version you are using.

Half lives of testosterone esters are as follows:

  • Sustanon/Omnadren 15 days
  • Cypionate 12 days
  • Enanthate 10.5 days
  • Propionate 3.5 days
  • Suspension 1 day or less
  • Phenylpropionate 4.5 days
  • Isocaproate 9 days
  • Decanoate 15 days
  • Undecanoate 16.5 days

Detection times

This term is a whole different thing, and it has nothing to do with half life as such.  Detection times mean the approximate amount of time you would need for the steroid to go undetected when being tested for performance enhancing drugs.  Consequently, this number is usually more important for those who are concerned with being tested for their job or for their sport.

Detection times of the main testosterone esters are as follows:
Testosterone cypionate, sustanon/omnadren, testosterone enanthate, and all other longer estered versions - approximately 3 months
Testosterone propionate 2 weeks
Testosterone suspension 1-2 days or less

How to use each testosterone ester

These two compounds are the exact same mixture of testosterone esters that contain 30mg of propionate, 60 mg of phenylpropionate, 60mg of isocaproate, and 100mg of decanoate.

The difference between the two is that omnadren is mostly used for HRT in Europe (hormone replacement therapy), while sustanon was designed for HRT in the USA, but it failed to catch fire.  Interestingly, many self proclaimed internet 'gurus' will say that they should be injected frequently because it contains propionate, but they do not realize that only 30mg of out of 250mg is propionate, so treating sustanon like propionate is ignorant.  Let us remember that sustanon and omnadren were designed to be used for long term HRT, and the idea behind it was to inject a large amount in order to let the esters pick up one after the other, so the user would only have to inject once every 2-3 weeks.

However, the problem is that these injections are somewhat painful, and each 1ML ampule only has 250mg, so it would be foolish for someone to use sustanon for a usual steroid cycle, unless they planned to be on for a long time.  In addition to that, it is more pricey than the cypionate or enanthate versions, neither of which are painful injections.  Therefore, sustanon's value for those who run standard 10 or 12 week cycles is low, and it makes more sense to opt for the enanthate or cypionate esters instead.  In spite of all these downsides, some guys swear by this version, perhaps because the different ester blend keeps the body guessing, or maybe it is just a placebo effect.

organon sustanon

Organon Sustanon 250

Testosterone Propionate
This one is popularly stacked with other short esters, and can be ran for 6 or 8 weeks with good results.  The secret is its short half life, which requires every day, or every other day, injections for best effectiveness.  Nonetheless, the injections can be very painful in those sensitive to post injection pain.

testosterone propionate

Testosterone Propionate

Testosterone Phenylpropionate
This one has a slightly longer half life than the propionate, but it's rarely used by itself, so you will usually find it as part of a mix like sustanon.  If you run it, you'll have to do injections around 3 times per week.

Testosterone Isocaproate
Just like the phenylpropionate, this ester is rarely used solo, but thanks to being part of sustanon it is quite a widespread ester.  Unlike the previous short esters, it has a 9 day half life, so injecting twice a week will work just fine.

Testosterone Decanoate
This one is also part of the sustanon blend, where it works as the long ester, since it has a hefty 15 day half life.  As a result, those who run this one solo can easily get away with injecting it once a week, or once every 10 days.  Nevertheless, you have to keep in mind that the decanoate will linger in your system for quite a while after stopping it.

Testosterone Undecanoate
With a half life of 16.5 days, the undecanoate ester has the longest half life of all the testosterone esters.  Hence, it can be injected once every 10-12 days and still keep even blood levels.

Testosterone Cypionate and Enanthate
These are the two of the most popular esters used in normal 10-12 week cycles.  The reason for their popularity is simple - they have relatively long half lives, which means less injections are needed, and they also are very smooth, so there is low chance of post injection pain.  Thus, it is not surprising that doctors who prescribe testosterone replacement therapy in North America will choose these, and they can easily be injected 1-2 times per week for good results.  The only difference between them is that their half lives are slightly different.

Testosterone Suspension
This one differs from the others because it is water based, and it is pretty much impossible to detect if you are a tested athlete.  The bad news is that you have to inject it at least every day, and the injections are extremely painful, proof of which are the many user complaints about knots forming at the injection site and swelling.  I do not recommend bothering with suspension, unless you are worried about being randomly tested.

Side Effects

Due to the fact that all of these versions of testosterone will aromatize, it is normal to have estrogenic side effects when using them.  These side effects include bloat, water retention, gynecomastia, insomnia, and even heart strain.  Fortunately, these estrogen related side effects can be avoided by using an aromatase inhibitor from the first day of the cycle, being aromasin and arimidex the most popular compounds of this class.

What's more, testosterone will convert to DHT (dihydrotestosterone) in the body, which can cause head hair follicle loss, oily skin, acne, and increased body hair.  The only way to help with this would be to use a 5-alpha-reductase inhibitor, such as finasteride or dutasteride.  However, inhibiting DHT should be a calculated risk because of the negative sexual sides you could face.


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Written by
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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