Last Updated: Apr 10, 2021
SteroidCycle.org is intended for informational purposes only and does not take the place of professional medical advice.

Testosterone undecanoate is a form of testosterone steroid containing a larger ester (undecanoate) than many other types. It is available in both oral and injectable forms, and there are different brand names for each.

Testosterone Undecanoate Cycle
Testosterone Undecanoate Cycle

The oral form of testosterone undecanoate is called Andriol, while the brand name of injectable Testosterone undecanoate is Nebido. Neither product is available in the USA as an approved drug on prescription, but they are prescribed in many other countries.

Testosterone undecanoate has been developed for medical use to treat low testosterone, but like other synthetic testosterone steroids it’s also very appealing to anabolic steroid users as it provides all the benefits you can expect from a testosterone steroid when used for performance enhancement or testosterone replacement purposes.

As you will see, Testosterone undecanoate is not likely to be the first choice of any bodybuilder or athlete looking to use a pure testosterone steroid, simply due to its large ester that results in a very slow release.

Although the hormone itself is exactly the same as we find in more commonly used testosterone compounds like Testosterone enanthate, the Testosterone undecanoate ester can make it difficult to gain benefits in a performance enhancement setting.

Author’s Note: The following guide is based on my personal experience and does NOT promote the illegal use of steroids (PEDs). I am currently using this supplement stack.

What is Testosterone Undecanoate?

This is a long acting, and slow release steroid that when used in injection form can last several months in the system. Due to this slow activity, its positive benefits can be very delayed and may not even begin to be beneficial until near the end of a normal length steroid cycle. This makes Testosterone Undecanoate less practical for many users of performance enhancing steroids compared with other esters of testosterone.

Andriol (Oral)

There is only one capsule size available, which is 40mg. Although there is 40mg of the active ingredient testosterone undecanoate in each capsule, only about one quarter or less will be absorbed by the body due to the oral method resulting in low bioavailability of the active ingredient.

This is one reason some guys will prefer the injectable form. Like all testosterone steroids, Andriol can can used in both bulking and cutting cycles. Testosterone encourages the retention of muscle when cutting and eating less calories than usual to encourage fat loss.

One of the benefits of Andriol is that unlike many other oral steroids, this one is not toxic to the liver because it does not pass through the liver. While this is a benefit, for most users the downsides will outweigh the lack of liver toxicity and this includes the high cost of the product when considering the high dosages that will be needed to reap the most benefits.

Nebido (Injectable)

For performance enhancement purposes, users would need to include Testosterone Undecanoate in a cycle that’s a minimum of 16 weeks in length, otherwise this slow acting testosterone form will not have enough time to provide any benefit. For this reason, most bodybuilders and athletes will choose one of the faster acting esters of testosterone instead.

Nebido will provide all the same benefits and effects that you experience with any other testosterone steroid, but they will take much longer to start happening. Most bodybuilders want to start seeing results within the first few weeks of a cycle, and this is simply not possible when using Nebido as a main anabolic compound. Only in the most specialist of circumstances will Nebido be a suitable choice for a bulking or cutting cycle.

Author’s Note: For real, NO-BS information on cycling steroids be sure to check out Straight From the Underground (my recommended underground steroid handbook). Everything in this book is based on first hand experience, not theory.

Meanwhile, if you are looking for something effective but don’t want to use steroids, here is my list of supplements that will help you with your quest in building muscles and getting leaner.

Testosterone Undecanoate Benefits (Testosterone Undecanoate Effects)

Testosterone Undecanoate, in both oral and injection form, will deliver the same benefits and effects as all esters of testosterone. The testosterone hormone itself is unchanged, and retains its 100 anabolic and 100 androgenic rating.

This steroid can be used in two main ways:

  • as a testosterone replacement at a low dosage during a steroid cycle where you need an external testosterone source to maintain levels and function due to the hormone suppression caused by other compounds
  • Testosterone Undecanoate can itself be used as a performance enhancement compound at higher doses.

The effects that testosterone, when used at high performance enhancement doses, will have on the male body include:

  • Increased nitrogen retention – a positive nitrogen balance is critical for muscle growth. If the nitrogen balance falls into the negative, the body can enter a catabolic state instead of anabolic and muscle will be lost. Testosterone will boost nitrogen retention to a higher level than can be naturally achieved without the use of steroids.
  • Enhances protein synthesis – encourages the cells to make more proteins which fuel muscle growth. Regular resistance training and quality protein food intake also promote protein synthesis, and when combined with a testosterone steroid at high doses this process is significantly enhanced; forming the basis for the substantial muscle mass growth you can achieve when using Testosterone Undecanoate.
  • Increases IGF-1 production – this growth hormone is vital for its anabolic effects on skeletal muscle and in the production of more protein. IGF-I may also stimulate muscle satellite cells which is a process that’s needed to fuel an increase in muscle size.
  • Increases red blood cell count – more red blood cells transporting more oxygen carrying hemoglobin and nutrients to the muscles means better performance, improved endurance and enhanced recovery through the increased removal of acid from cells that oxygen is capable of.
  • Decreases levels of glucocorticoids – these stress hormones naturally increase when undertaking intense physical exercise and they contribute to a loss of muscle mass by causing a loss of protein and having a negative effect on insulin which is an important anabolic regulator. Testosterone can reduce levels of glucocorticoids so you can avoid this muscle wastage and remain anabolic.

If you are experienced using any other form of testosterone such as cypionate, enanthate, propionate or testosterone suspension, you will be familiar with all the benefits and effects of Testosterone Undecanoate as the hormone is unaltered.

Testosterone Undecanoate Dosage and Cycle Length

Both forms of Testosterone Undecanoate present challenges when used in a performance enhancement steroid cycle. Most experienced and new steroid users will find Testosterone Undecanoate to be a much less practical and effective choice of compound compared with the much more commonly used esters of testosterone like enanthate.

While a great benefit of this slow acting injection form is how sparse your injections will be, this needs to be weighed up with how long you’ll be waiting to see any results.

Andriol (Oral) Dosage and Cycle Length

To get performance enhancement benefits from Andriol, you would need to use a very high dose of this oral steroid. This is quite an expensive steroid, and additionally there is no scientific information available about the health impacts of consuming such high doses over long periods of time. Up to 500mg daily would need to be taken of Andriol due to the low bioavailability of each 40mg capsule. The cycle length would need to be similar to a standard steroid cycle at 8 to 12 weeks long.

Nebido (Injectable) Dosage and Cycle Length

If you’re wanting to do a short steroid cycle, then Nebido won’t fit the bill for you because your cycle length with this compound will need to be at least 16 weeks because of how long this injected hormone takes to start having an effect. 8 or even 12 weeks just doesn’t give Nebido enough time to take full effect.

Dosage of Nebido will depend on what your purpose for using it is: as a testosterone support when using other compounds, 1000mg to last 12 weeks is suitable but again, because it is such a slow acting compound it will not provide the immediate relief to testosterone suppression that you’ll be needing so there is unlikely to be a scenario when it will be used in a performance enhancement setting for this purpose.

When using Nebido as a primary anabolic compound or alongside other steroids in a stack, the dosage of 1000mg can be more frequent; at least once per month or in some cases twice monthly. Most users will not benefit from a compound like Nebido that takes a considerable amount of time to kick in, and therefore you are likely to be selecting one of the much faster acting forms of testosterone.

Testosterone Undecanoate for TRT

When used medically for low testosterone treatment, Nebido is usually injected every 3 months at 1000mg. But again, due to the fact steroid users will be using other compounds that have a rapid effect on natural testosterone production, Nebido is too slow acting to be useful as a testosterone replacement during most steroid cycles. While the oral Andriol is faster acting, daily doses of up to 160mg as a testosterone replacement can make this a very expensive option when compared to other testosterone compounds.

Andriol vs Nebido

The only difference between these two forms of Testosterone Undecanoate are the method of administration; Andriol is an oral capsule, while Nebido is an injection. The testosterone hormone is exactly the same, with the same ester attached.

The difference occurs in the body thanks to the way each one is consumed and metabolized, with Andriol having a much shorter elimination half life and faster action, but needing to be administered often to keep blood levels an the optimal level.

Although each capsule of Andriol contains 40mg of testosterone, the majority of this is not taken up by the body; in fact less than 10% of the hormone is absorbed. This results in a significantly higher dosage being needed in order to meet your targeted dosage amount; making Andriol almost impossibly impractical and expensive to use for performance enhancement due to the significant amount of the steroid you would need to purchase and use.

In contrast, injecting Nebido puts you on a slow course to receive the full dosage of testosterone over a long period of time. Bodybuilders will need to wait a considerable time – measuring many weeks to months – to see results from Nebido. For that reason alone it is not often considered a steroid that is useful for most performance enhancement cycles.

What results can I expect using Testosterone Undecanoate?

The first thing to know about using Testosterone Undecanoate is that results will be very slow, and therefore it requires a very long cycle. For some users, the cycle will need to be much longer than you’re normally comfortable with and this can be enough to rule out Testosterone Undecanoate.

If you decide to go ahead with this compound, once its effects finally kick in you can expect all the same benefits as you’d see with any other testosterone ester. The hormone itself remains exactly the same. And testosterone certainly comes with substantial benefits for the bodybuilder or performance user, including:

  • Muscle mass growth – you’ll find it easier and faster to gain lean muscle mass, provided you’re sticking to an intense workout regime. While testosterone isn’t the most powerful muscle gaining or bulking steroid we can use, it will provide quality gains that can be maintained.
  • Muscle retention – when cutting you’ll stay in an anabolic state so muscle mass isn’t being lost while on a calorie deficit diet.
  • Increased energy and mental concentration – testosterone comes with a host of benefits including optimizing sleep quality, boosting energy and focus and giving a boost to the libido as well. These are all natural functions of the testosterone hormone itself which will all contribute positively to your bodybuilding goals.

Men who are suffering with low testosterone will see substantial benefits, such as the reversal of low testosterone symptoms like loss of libido, weight gain, poor sleep, low energy, lethargy, lack of focus, and depression.

In short, all the serious and debilitating symptoms of low testosterone – of which there may be dozens – will diminish or disappear completely when using this steroid (provided their only cause was due to low testosterone). Men wanting to make use of Testosterone Undecanoate to treat low testosterone should speak to their doctor and have levels medically tested before proceeding.

Testosterone is the most important naturally occurring androgen hormone in men and its functions and benefits for both everyday health and for performance enhancement can not be overstated. Potential users of Testosterone Undecanoate simply need to be aware of the pros and cons of this particular ester of testosterone to weigh up whether it’s the right option, when we have many other potentially easier forms of testosterone steroids to use.

Side Effects from Testosterone Undecanoate Cycle

The same expected side effects that come with using any form of testosterone steroid for performance enhancement can be a possible risk when using either the oral or injectable forms of Testosterone Undecanoate. Experienced steroid users will have a good idea of the signs to watch out for, and how to mitigate some of the more serious or undesirable side effects.

The higher the dosage of Testosterone Undecanoate and the longer it’s used for, the higher risk of side effects or more severe effects are likely to be. Most men tolerate taking any form of testosterone well, but each individual has a different risk profile when it comes to potential negative effects.

Here are the main side effects to be aware of when using either the oral or injection form of Testosterone Undecanoate:

Androgenic Side Effects

Side effects relating to androgenic activity will vary between each male user as some guys are much more predisposed genetically to acne and hair loss, while others will have no issues at all in these areas and again, the higher the dosage the more the risk increases of androgenic effects developing.

Female users can expect, even at low doses, to be at risk of virilization symptoms that include a deeper voice and body hair growth, at which point the steroid should be discontinued to allow these effects to subside.

Estrogenic Side Effects

Higher doses of testosterone can result in the development of estrogenic side effects like gynecomastia and water retention due to testosterone converting to estrogen through aromatization. When gyno is left to develop unhindered it can be difficult or impossible to reverse without surgery, and water retention can lead to dangerous increases in blood pressure.

Controlling estrogenic side effects is therefore really important, and even more so when you’ll be using other potentially more estrogenic steroids in your cycle. Testosterone is naturally a highly aromatizable steroid, but experienced users should have no issue with controlling these effects. Almost all users will want to make use of an aromatase inhibitor drug during the cycle to combat these effects and prevent them from developing at all. Arimidex is a popular and effective option.

Cholesterol

Low doses for the purpose of testosterone replacement are unlikely to have a noticeably negative impact on cholesterol levels, but studies show that when testosterone is used alongside an aromatase inhibitor, which most users will be doing to combat estrogenic effects, HDL cholesterol levels can decrease.

Those with existing cholesterol problems should monitor levels closely, but all Testosterone Undecanoate users should be sticking with a cholesterol friendly diet with plenty of omega-3 foods and including cardio work in your workouts regularly.

Testosterone suppression

Male users can expect their natural testosterone production to be suppressed when using this steroid, with the more severe suppression occurring the higher your dosage is. In any case, and especially when stacked with other suppressive steroids, a proper PCT plan needs to be in place which will start either towards the end of your cycle or some time after it, depending on the half lives of any other compounds you’re using.

If you choose to use the oral form of this steroid you might be concerned about liver toxicity. However Andriol is not of the C17-aa steroid type, so does not stress the liver like many other oral steroids do. Nebido is also not known to be a hepatotoxic anabolic steroid.

Testosterone Undecanoate Post Cycle Therapy

Providing the body with an external source of testosterone will always result in your natural testosterone function becoming suppressed or even stopping completely. How severe this suppression is will depend on your Testosterone Undecanoate dosage and any other compounds being used in your cycle.

Once your cycle ends, you will be in a state of low testosterone while the body starts to ramp up normal production again. But this can be a slow process, so post cycle therapy is needed to stimulate testosterone function quicker so you can avoid serious low testosterone symptoms as you recover from steroids, and maintain the gains you’ve made during your cycle.

Your PCT schedule when using Testosterone Undecanoate will also depend on any other compounds being used and which form of Testosterone Undecanoate you are using. The very long lasting Nebido can continue taking effect two to three months after your last injection, so PCT can be delayed until that time.

A standard PCT protocol of HCG combined with either or both Nolvadex and Clomid carried out for 4 weeks with a tapering dosage will suffice for the majority of users.

Common Q&A Related to Testosterone Undecanoate

How long does testosterone undecanoate stay in your system?

In its injectable form, Nebido has an extremely long half life of up to three months. This makes it slow acting and allows it to stay in the system at optimal levels for a long time compared with other testosterone esters. This means only one Nebido will be needed every few weeks. Andriol has a much shorter half life as an oral steroid of less than 12 hours, requiring regular administration and exiting the system quickly.

Are Andriol Testocaps safe?

The oral Andriol capsules have been approved for pharmaceutical use in many countries. While like all medications, they can come with side effect risk, it is considered safe when used at the recommended dosage. For performance enhancement, when dosage might be considerably increased, users increase their risk of side effects. Andriol does not come with the risks to liver health like many other oral steroids do.

How quickly does Nebido work?

Nebido is a very long lasting and slow acting form of testosterone. It can take many weeks to start seeing any benefits from this form of testosterone, which is why a cycle of at least four months is recommended. For most steroid users this will not be practical which is why Nebido is rarely used for performance enhancement.

What are the side effects of Nebido?

Nebido comes with all the same possible side effects as you’ll find with any testosterone steroid, although these effects can be delayed in a cycle because of the much slower acting nature of this compound.

Potential side effects of Nebido include alterations to your cholesterol levels, estrogenic effects like gyno and water retention, androgenic effects such as acne and male pattern hair loss in susceptible people, and suppression of your normal testosterone production. Higher doses of Nebido will increase your chances or severity of these side effects.

Is Nebido injection painful?

Unlike other forms of testosterone which often need to be injected several times weekly, a cycle of Nebido may only require you to inject the hormone three or four times in a long cycle. This helps you avoid the problems that come with frequent intramuscular injections like pain, swelling and inflammation, and needing to constantly rotate injecting sites.

Your injecting technique will largely determine how painful it is. Most users will feel a feeling of pressure rather than pain; but if pain occurs you should refine your injecting technique or inject into a different muscle. Some users might feel some pain or sensitivity at the injecting site in the days following administration.

Is testosterone undecanoate legal?

In some countries Testosterone Undecanoate is prescribed as a testosterone replacement therapy prescription drug. Without a prescription, it is not legal to buy or use this steroid. Neither Nebido or Andriol are amongst the most common steroids used by bodybuilders, so they are not in great demand on the black market.

Andriol Testocaps will be much easier to find available to purchase underground compared to the more uncommon injectable Nebido. The cost of one Andriol cycle can easily reach $1000, which is another reason that most steroid users will favor other testosterone esters.

My Conclusion and Recommendation

Testosterone Undecanoate is an AAS steroid. It is a synthetic form of the hormone testosterone, with a large ester attached which controls the rate of release of the hormone in the body once it has been consumed orally or through an injection. The testosterone hormone is exactly the same as that which occurs naturally in the body and has an anabolic and androgenic ratio of 100:100.

It is used to treat medical conditions of low testosterone in men. Bodybuilders and athletes can use this steroid to enhance performance and results, particularly to encourage muscle growth and to help maintain lean muscle while cutting. It can also be used to provide testosterone support when using other steroid compounds, but it’s very slow release means it is unlikely to be a viable option for most users.

Author’s Note: I am not advising anyone to use steroids. I’d either pick staying natural or using steroids. There is NO in between. If your idea is to do just few cycles and never touch steroids again, you better don’t even start.

Fortunately, for those of you who are looking for something effective but don’t want to use steroids, here is my list of supplements that I am currently using and feel work to improve your results! For those who follow me, you know I’d never steer you wrong.

If you enjoyed this guide and would like more real, NO-BS information on using steroids, then pick up Straight From the Underground (my recommended underground steroid handbook). Everything in this book is based on first hand experience, not theory.