Steroid Half-Lives


What Are Steroid Half-Lives? What Is a Half-Life?

The concept and idea of a half-life and half-lives is extremely important to the understanding of not just anabolic steroid use, but the use of any drugs, substances, and even foods that are consumed. The concept of a half-life is not just limited to steroid half-lives or even to the half-lives of drugs. This is a concept within science that applies to almost all disciplines of science: physics, biology, chemistry, and more. There are several different definitions of what a half-life is (depending on the area of scientific study), but although there are different definitions, they only differ ever so slightly. The general definition of a half-life is the same.

However, the dictionary definition of half-life in physics is as follows: Physics. The time required for one half the atoms of a given amount of a radioactive substance to disintegrate.

The dictionary definition of half-life as it pertains to biology is as follows: Also called biological half-life. Pharmacology. The time required for the activity of a substance taken into the body to lose one half its initial effectiveness.

The general or informal dictionary definition of half-life is as follows: Informal. A brief period during which something flourishes before dying out.

Different dictionary definitions will differ from one another, but the general concept of a half-life as it pertains to biology and pharmacology is: the time required for a substance, drug, or food to be reduced to half of the original administered dose once in the body. For example, if an individual injects 100mg of Testosterone Propionate, which exhibits a half-life of 4.5 days, this means that in 4.5 days, only 50mg of the substance will be remaining in his or her body.

The concept of steroid half-lives is extremely important to understand, because it allows the individual to understand the amount of time a particular anabolic steroid or drug is actively remaining in the body after administration. This will assist the individual in better planning and organizing his or her cycle appropriately, and understand how to properly time the administration of the anabolic steroids so as to achieve the most effective, comfortable, and safe cycle. The proper understanding of half-lives is very important for the understanding of how long it might take before a particular compound reaches peak optimal blood plasma levels in the body. This is very important, because the results and gains experienced from anabolic steroids do not normally occur until these peak optimal blood plasma levels are achieved in the body. The longer steroid half-lives are for a particular anabolic steroid, the longer it will take for the gains to ‘kick-in’ on the cycle.

The importance of understanding steroid half-lives is also an issue of safety. Without a proper and thorough understanding of the half-live of a drug, it is very possible for an individual to improperly administer the drug and result in self-injury, harm, or even death. Most of the time, improper administration timing according to the half-lives of different steroids used can result in a very uncomfortable experience, which will most often increase the severity and incidence of side effects that occur. The understanding of steroid half-lives is one of the very first concepts that should be grasped by any individual looking to use anabolic steroids

What Affects the Different Steroid Half-Lives?

Anabolic steroid half-lives are affected by a few different factors, the three primary of which are: route of administration, esterification, and resistance to metabolism.

The route of administration has a very significant impact on the half-life of an anabolic steroid. There are two primary routes of administration for anabolic steroids: oral and injectable. A third route would be transdermal patches, gels, or creams, which are methods of absorption through the skin. However, anabolic steroid use for the purpose of physique and performance enhancement are almost always achieved through either oral administration, or injection. There are other less popular methods of administration as well that have been used, such as implantation pellets and sublingual and nasal applications, though they are far too rare to bother covering. The oral route of administration grants some of the shortest steroid half-lives among the different compounds. This is due to the fact that the vast majority of anabolic steroids are un-esterified, and are ingested in their pure and immediately active format. Because the oral route of administration presents no delay in the release of the anabolic steroid to the bloodstream, the hormones are instantaneously active and playing an active role in the body as soon as they hit the bloodstream (after they make the first pass through the liver). Although these oral anabolic steroids undergo a first pass through the liver, the amount of metabolism through the hepatic (liver) pathway does not slow down the release of the hormones into the bloodstream by much. In fact, one of the reasons as to why oral steroid half-lives are much shorter than injectable steroid half-lives is because of the immediate exposure to liver metabolism, which facilitates faster metabolism and elimination of the hormone in and out of the body. Oral anabolic steroid half-lives generally range from 4 hours to 48 hours, depending on the anabolic steroid used.


Injectable anabolic steroids consist of two different types: oil-based injectables, which form a depot in the muscle tissue they are injected in, and slowly released from the injection site into the bloodstream. The second type are water-based injectables, known as suspensions, where the hormone is suspended in microcrystals that are in a water base. Once water-based suspensions are injected into muscle tissue, the microcrystals are slowly dispersed and released into the bloodstream into circulation. Injectable steroid half-lives are, for the most part, significantly longer than oral anabolic steroid half-lives. The reason for this is because of the nature of oil-based and water-based injections, which are designed to form a depot in the muscle tissue they are injected in, after which a slow release from the injection site into the bloodstream occurs in the hours or days after the injection. This extends the steroid half-lives quite significantly, but it is actually an additional factor that extends the injectable steroid half-lives even more: esterification. Nearly all anabolic steroids, especially oil-based, are esterified so as to deliberately extend their half-life and to make them more fat soluble in order to better dissolve in the carrier oil. The only exception to this is Testosterone Suspension and Winstrol (Stanozolol), both of which are injectable anabolic steroids that are not esterified at all. Injectable anabolic steroid half-lives generally range from 24 hours to as long as 15 days or more, depending on the anabolic steroid used and whether or not it is esterified (and what kind of ester is bound to it).

Esterification is perhaps the most influential contribution to the different steroid half-lives. Esterification is a process whereby a carboxylic acid is bound to an anabolic steroid’s 17-beta hydroxyl group. This type of bonding is known as esterification (also known as an ester bond). The carboxylic acids that are esterified to an anabolic steroid are of different and varying lengths, normally in the form of a carbon chain. The longer the carbon chain of the carboxylic acid, the longer it is, and therefore the longer the anabolic steroid’s half-life will be extended. Once the anabolic steroid is injected into the body, it is slowly released from the injection site into the bloodstream, and once in the bloodstream, the body’s esterase enzymes will break off the ester from the anabolic steroid. Longer ester bonds will require more time for these enzymes to free the hormone from the ester. But once the anabolic steroid hormone is broken free from the ester, what remains is a pure and active anabolic steroid that is free to do its work in the body. For example, pure and un-esterified Testosterone expresses a half-life of approximately 4 – 24 hours, but Testosterone Propionate expresses a half-life of 4.5 days, and Testosterone Enanthate expresses an even longer half-life of 7 – 10 days in the body. Esterification was deliberately devised by scientists back in the 1930s in order to deliberately extend the half-life of different anabolic steroids. Most anabolic steroids when un-esterified will express an extremely short half-life, making them very impractical for medical or clinical use due to the fact that they necessitate far too frequent injections for most people’s comfort. Esterification successfully extends the half-life of anabolic steroids to lengths that would require far less frequent injections, and therefore more comfortable injection schedules for patients.

Although nowhere near as influential as the previous three factors involved in the manipulation of steroid half-lives, the amount of resistance to the body’s metabolism has an effect on the half-life of a given anabolic steroid. For example, some oral anabolic steroids exhibit a half-life of 4 hours, while others will exhibit a half-life of 24 hours. The reason for this is because some anabolic steroids are much more resistant to metabolism in the liver (and/or elsewhere in the body), and therefore are not broken down as easily or as quickly. This means that the anabolic steroid in question would express a longer half-life in the body. Ultimately, however, all drugs, anabolic steroids, foods, chemicals, and compounds eventually undergo metabolism and elimination from the body – there is no such anabolic steroid or drug that will last forever in its active state in the body.

What Steroid Half-Lives Do and How to Structure Cycles According to Them

Because there are different anabolic steroid half-lives for the different anabolic steroids in existence, not every anabolic steroid can be administered in the same manner or in the same frequency. Dianabol (Methandrostenolone), for example, exhibits a half-life of approximately 4 – 6 hours, which might require multiple daily administrations in order to maintain stable blood levels of the hormone. The same might not be said for Winstrol (Stanozolol), which expresses a half-life of 9 hours in the body, and therefore individuals could easily get by with ingesting their full dose all at once.

It is important to understand as well that for the purpose of performance and physique enhancement, frequent administration of anabolic steroid is very necessary in order to maintain stable and optimal blood plasma levels. For therapeutic medical use, the administration of an anabolic steroid on the last day of its half-life might be acceptable, but for the purpose of performance and physique enhancement, the administration and dosage protocol changes dramatically. The intention at this point is no longer for therapeutic use, but now for increased performance and/or muscle mass and strength. Therefore, higher than normal (therapeutic) physiological bodybuilding doses are required, as well as a higher frequency of injections are required so as to maintain optimal peak blood plasma levels of the hormone. For example, a TRT (Testosterone Replacement Therapy) does not have to be concerned about performance increases from week to week (or even day to day), but athletes and bodybuilders must.

While the human body manufactures an endogenous Testosterone level in the range of 70mg/week, the Testosterone dosage required for physique and performance enhancement must sit well above that, with a minimum being in the range of 300 – 500mg per week for beginners, for example. Intermediate and/or experienced anabolic steroid users can venture even higher than that. In addition to the higher bodybuilding dosage, the injections must be administered much more frequently. While TRT patients can ‘get by’ with a single 250mg injection of Testosterone Enanthate once per week (or even once every two weeks as is commonly applied clinically), an athlete or bodybuilder would have to administer 250mg of Testosterone Enanthate twice per week (for a total of 500mg) in order to experience a steady onset of performance and physique enhancing benefits. This is very necessary due to a constant steady peak blood plasma level of the anabolic steroid that is necessary for constant biological action within muscle tissue in the body. Testosterone Enanthate, as mentioned earlier in this article, exhibits a half-life of 7 – 10 days, but although its half-life is 7 – 10 days, sharp declines in blood plasma levels begin to occur several days before the end of the half-life period. When performance and physique enhancement is desired, the administration of doses must occur more frequently in order to keep blood plasma levels elevated as best as possible. For medical purposes such as TRT, sharp spikes and peaks and valleys in blood plasma levels can be afforded (although it is still not optimal), as the patient is simply utilizing Testosterone to obtain normal physiological levels, and is therefore not particularly concerned with dramatic performance or physique changes on a weekly basis.

The dosages of anabolic steroids administered on a daily or weekly basis should be split evenly per administration. For example, if an individual is to administer 500mg per week of Testosterone Enanthate as two injections per week, they would ideally administer 250mg per injection. An individual administering 50mg per day of Dianabol would have to ideally ingest their doses once every 2 – 4 hours, which might work out to 2 administrations of 25mg per administration during the waking hours.  Some additional practical examples are the following:

Testosterone Propionate half-life: 4.5 days. Optimal injection frequency: every other day (daily is even better).

Trenbolone Acetate half-life: 3 days. Optimal injection frequency: every other day (daily is even better).

Testosterone Cypionate half-life: 10 – 12 days. Optimal injection frequency: twice per week, each injection split evenly between each other (for example, Monday and Thursday).

Testosterone Suspension half-life: 4 – 24 hours. Optimal injection frequency: once per day (multiple times per day is even better).

Dianabol (Methandrostenolone) half-life: 4 – 6 hours. Optimal administration frequency: once every two to four hours.

Maintaining steady and stable blood plasma levels with frequent administrations long before the anabolic steroid’s half-life period has ended also assists the user in performing a much more comfortable cycle that is void of side effects. Because peaks and valleys in blood plasma levels are avoided, the incidence of side effects becomes much lower. Side effects tend to present themselves the most during periods of fluctuating hormone levels, where the imbalance of different hormones takes its toll on the body.

Frontloading Steroids

Frontloading is a practice utilized by anabolic steroid using bodybuilders and athletes in an attempt to elevate blood plasma levels of the anabolic steroid as quickly as possible so as to experience gains and the ‘kick-in’ period much quicker. This is normally done with long-estered anabolic steroids such as Testosterone Enanthate, Testosterone Cypionate, Deca-Durabolin (Nandrolone Decanoate), etc. as these anabolic steroids express fairly long steroid half-lives. Anabolic steroids that express longer half-lives tend to kick-in much later (a half-life of 7 days or longer is considered to be quite long). These long-estered anabolic steroids often require several weeks of administration (4 – 6 weeks) before performance and physique changes are experienced. This is due to the very slow release of the hormone in the body due to the very long steroid half-lives, and therefore result in a very slow build-up to the optimal blood plasma levels that are required for significant gains to occur.

The interesting point to understand is that shortly after the injection of any compound, whether it is a short-estered anabolic steroid or a long-estered one, a sharp and fast release of the hormone in the body always occurs within the day or two following injection. Blood plasma levels rise quite rapidly before beginning to decline. With long-estered anabolic steroids, the build-up of the hormone to the intended optimal peak effective level is achieved slowly over time (this has been mentioned many times already throughout this article. For example, if an individual wishes to run a cycle of Testosterone Enanthate at 500mg per week, the fact of the matter is that the body will not actually contain 500mg of Testosterone Enanthate until several weeks into the cycle if the user merely administers only 500mg of Testosterone Enanthate from the beginning.

The practice of frontloading avoids this by having the user administer double (or even triple) the original intended dose within the first week (or first few days) of the cycle, depending on the anabolic steroid used.

The normal progression of blood level buildup is as follows (using Testosterone Enanthate as the example compound, for the purpose of explanation, its half-life will be regarded as 7 days):

Day 1: 500mg
Day 7: 250mg remaining from the previous injection + 500mg freshly injected = 750mg total
Day 14: 375mg remaining from the previous injection + 500mg freshly injected = 875mg total
Day 28: 437.5mg remaining from the previous injection + 500mg freshly injected = 937.5mg total
Day 35: 468.75mg remaining from the previous injection + 500mg freshly injected = 968.75mg total
Day 42: 484.38mg remaining from the previous injection + 500mg freshly injected = 984.38mg total

As demonstrated, it took until 42 days before blood plasma levels started to come very close to reaching the optimal 500mg per week level in the bloodstream. The amount to be concerned over is the amount that is remaining in the body before the next injection. Now, the frontloading method of double-dosing the intended weekly dose will be compared as to how long it will take for optimal blood plasma levels of 500mg/week to be achieved:

Day 1: 1,000mg
Day 7: 500mg remaining from the previous injection + 500mg freshly injected = 1,000mg total
Day 14: 500mg remaining from the previous injection + 500mg freshly injected = 500mg total

As demonstrated, it took until day 7 before blood plasma levels of 500mg in the body are achieved with the frontloading method. By comparison, it would take 42 days for this dose to be achieved in the body by simply administering 500mg per week. By administering double the intended dose on the first day (or in the first week) of the cycle, optimal intended blood plasma levels are acquired by the second week. The result is a faster onset of gains and performance and physique changes compared to the standard dosing method. Typically with frontloading, most users will report their long-estered compounds to ‘kick-in’ approximately 3 or 4 weeks into their cycle compared to 4 – 6 weeks.

The only possible downside to the frontloading method is a faster onset of side effects for the user, especially those more sensitive to them. Individuals who fall into this category might want to avoid the practice of frontloading. Users who are brand new to a particular compound might also want to do the same.

List of Steroid Half-Lives

The following is a list of anabolic steroid half-lives (in alphabetical order):

Anadrol (Oxymetholone): 8 – 9 hours
Anavar (Oxandrolone): 9 hours
Deca-Durabolin (Nandrolone Decanoate): 15 days
Dianabol (Methandrostenolone): 4.5 – 6 hours
Equipoise (Boldenone Undecylenate): 14 days
Halotestin (Fluoxymesterone): 9.5 hours
Masteron (Drostanolone Propionate): 4.5 days
Nandrolone Phenylpropionate: 4.5 days
Omnadren: 15 – 18 days (variable due to the mixture of four different ester types)
Parabolan (Trenbolone Hexahydrobenzylcarbonate): 14 days
Primobolan, oral (Methenolone Acetate): 2 – 3 days
Primobolan, injectable (Methenolone Enanthate): 7 – 10 days
Sustanon 250: 15 – 18 days (variable due to the mixture of four different ester types)
Testosterone Cypionate: 10 – 12 days
Testosterone Enanthate: 7 – 10 days
Testosterone Propionate: 4.5 days
Testosterone Suspension: 2 – 4 hours (some reports as long as 39 hours)
Trenbolone Acetate: 3 days
Turinabol (4-chlorodehydromethyltestosterone): 16 hours
Winstrol, oral (Stanozolol): 9 hours
Winstrol, injectable (Stanozolol): 24 hours

A final concluding note should be made on anabolic steroid half-lives, and this goes for any drugs, chemicals, or foods: half-lives are not set in stone figures, and only approximations and ranges can be given. Half-lives are also very susceptible to the individual metabolism of the person using the drugs, as some individuals may possess a faster ability to metabolize hormones than others, while others can be much slower at this process. For example, while the half-life of Testosterone Enanthate is that of 7 – 10 days, there might be some individuals that might metabolize the drug within 5 days, and others that might metabolize it within 12 days or more.