Deca Durabolin (Nandrolone): The Ultimate Guide

Dr George TouliatosDisclaimer: The following article is for educational purposes only and NOT to promote the use of illegal steroids. If you have any questions or concerns, Dr. Touliatos is currently available for consultations.

Deca durabolin (nandrolone decanoate) is an injectable anabolic steroid, typically utilized by bodybuilders in the off-season for mass building.

Deca durabolin was first described in 1960 with pharmaceutical giant, Organon, bringing it to market 2 years later.

Deca durabolin was Organon’s second formulated nandrolone ester, following Nandrolone phenylpropionate (NPP).

Deca durabolin was initially synthesized to treat patients suffering from cachexia (muscle wasting).

It is one of the only anabolic steroids still prescribed today, effectively treating HIV/AIDS and anemia patients, thanks to its anabolic and erythrocytosis properties.

By the 1970’s deca durabolin had become one of the most popular anabolic steroids in the world (which remains the case today). It was known to be cycled by top bodybuilders during the golden era (such as Arnold Schwarzenegger), commonly being stacked alongside dianabol during bulking cycles.

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Deca Durabolin Benefits

Muscular Size and Strength

Deca durabolin promotes muscular hypertrophy (size) and strength, causing significant changes in body composition after several weeks of use.

Deca durabolin promotes lean mass, due to it stimulating protein synthesis and creating a positive nitrogen balance inside the muscle cells.

It is not as potent as other bulking AAS (anabolic-androgenic steroids), such as: anadrol, dianabol, superdrol or trenbolone.

However, some bodybuilders prefer deca durabolin over such steroids, due to its safety profile.

Well Tolerated

It is an FDA approved medicine, which is indicative of its low risk level. It has been successfully prescribed to women for breast cancer treatment (1) and children suffering from dwarfism (2); without notable adverse effects.

Deca Durabolin also increases collagen synthesis, improving the health of ligaments and tendons. This is particularly beneficial to bodybuilders and powerlifters regularly lifting heavy weights and thus being more prone to injury.

Joint Anti-Inflammotry

Deca durabolin also promotes fluid retention, that aids in lubricating the joints. This can help to minimize, alleviate or prevent join pain in bodybuilders who have lifted weights for many years.

In one study, deca durabolin was given to 18 men experiencing joint pain. Following treatment, 72% reported a reduction in pain and 28% required less painkiller medication (3), demonstrating potent anti-inflammotry effects of the steroid.

No Hepatotoxic Effects

Many steroids, particularly orals, can exhibit toxic effects to the liver.

If abused, such AAS can cause peliosis hepatis (blood filled cysts) or cirrhosis (failure) of the liver.

However, deca durabolin is an injectable steroid that bypasses the liver, causing little to no hepatic strain.

Long Esters

Deca durabolin is a slow-acting steroid, containing long esters, hence why cycles typically last up to 12 weeks.

This can be disadvantageous to some bodybuilders looking for rapid results, but for others who want serum testosterone levels to remain steady in the blood stream (to minimize side effects); this is largely beneficial.

Furthermore, when deca durabolin is stacked with other steroids, it enables users to continue experiencing results in the latter stages of a cycle. In comparison, other AAS can peak early or cause more side effects than benefits towards the end of a cycle, due to high levels of toxicity.

Deca Durabolin Side Effects


Deca durabolin will cause mild alterations in LDL/HDL cholesterol scores, provoking elevations in blood pressure. However, the risks of developing heart disease are relatively low on deca durabolin, with such cardiac effects being mild.

All anabolic steroids will have a negative effect on blood lipids, as they are all essentially forms of exogenous testosterone. However, deca durabolin is among the most cardiovascular-friendly steroids available (alongside testosterone).

Deca Dick

Deca durabolin is infamous for its sexual side effects, inducing a decrease for sexual desire and performance; often leading to erectile dysfunction (deca dick).

The reason why men may struggle to get an erection on deca durabolin is due to its deficiency in androgncicity. Androgenic steroids facilitate nitric oxide production, which is crucial in the role of supplying blood flow to the penis. Thus, deca durabolin may compromise circulation in this regard.

Also deca durabolin raises prolactin levels, a lactating hormone, that can decrease arousal or sexual interest.

This combination of low nitric oxide levels and high prolactin is often a recipe for disaster in the bedroom.

However, bodybuilders often combat this by stacking deca durabolin with an androgenic steroid, ensuring that N.O levels stay high. Examples of such androgenic compounds are: testosterone, anadrol and trenbolone.

Bodybuilders may also supplement with cabergoline (when taking deca), due to its prolactin-lowering effects, caused by it strongly binding to dopamine receptors.

Low Testosterone

Low testosterone levels will occur on deca durabolin, with it being a highly suppressive anabolic steroid.

Thus, a PCT involving tamoxifen (nolvadex) or clomiphene (clomid) may be administered to help stimulate endogenous testosterone production, following discontinuation of the drug.

Estrogen and Progesterone

Deca durabolin has low estrogenic properties, with just a 20% aromatization rate of testosterone. However, deca durabolin users can often experience estrogen-like side effects; due it significantly increasing progesterone.

Progesterone is a female sex hormone (like estrogen) that has a stimulating effect on breast tissue in the mammary glands, potentially causing gynecomastia.

Interestingly, anti-estrogens (such as anastrozole) are effective inhibitors of progesterone receptor expression and thus reduce the risk of gynecomastia in men (4).

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Deca Durabolin Cycles

Deca Durabolin-Only Cycle

Deca durabolin is predominantly used for bulking purposes, however due to it only building moderate amounts of lean muscle (by bodybuilding standards), it is often cycled with other, more potent AAS.

Generally stacking steroids together leads to an increase in side effects, such as further elevations in cholesterol. However, in deca durabolin’s case, stacking may help to prevent some of its negative effects regarding sexual health.

Thus, deca durabolin-only cycles are seldom among bodybuilders, in a bid to keep androgen levels high, mitigating the risk of erectile dysfunction on-cycle.

However, if a bodybuilder were to utilize a deca durabolin-only cycle, these are the typical dosages they would use (below):

deca durabolin only cycle

Deca Durabolin and Dianabol Cycle

Dianabol (methandrostenolone) is one of the most popular steroids available, due to its exceptional mass-building effects.

Dianabol сompliments deca durabolin during a bulking cycle, with deca durabolin amplifying the anabolic nature of dianabol, enhancing muscle hypertrophy (size) and strength.

Dianabol’s two main adverse effects are hypertension and liver toxicity. Thus, by stacking dianabol with deca durabolin, users will not be aggravating these two symptoms; with deca being an injectable and only having mild effects on blood lipids.

deca durabolin dianabol cycle

This steroid cycle is taken by experienced steroid-users, who already have a testosterone cycle under their belt and have built up some tolerance to anabolic steroids.

This stack has the power to add 30-40lbs of weight gain to a user, accompanied by 50-70lbs of increased strength on compound lifts.

Some of the weight gained will be in the form of water, thus bloating and water retention is likely; with dianabol having the aromatase enzyme active.

This cycle has the potential to cause gynecomastia from high levels of progesterone (deca durabolin) and estrogen (dianabol). Thus, an AI (anti aromatase inhibitor) can be utilized to combat the conversion of testosterone to estrogen, albeit at the expense of exacerbating blood pressure.

This cycle was perhaps the most common duo used in the golden era by the great, classic bodybuilders. Such a cycle produced exceptional levels of mass, without androgenic effects; enabling users to keep their hair intact and prevent male pattern baldness (androgenetic alopecia).

Deca Durabolin and Anadrol Cycle

Anadrol (oxymetholone) is a similar compound to dianabol, being an oral steroid that possesses immense muscle-building and strength enhancing effects.

The main benefit of stacking anadrol with deca durabolin, is due to its androgenicity.

Anadrol can help to alleviate impotence associated with deca durabolin, due to higher nitric oxide production; improving blood flow to the penis.

deca anadrol cycle 2

The above cycle is suitable for advanced steroid-users only, due to anadrol’s harsh effects on the body; particularly cardiovascular and hepatic strain.

Anadrol ran by itself has the power to cause hypertension, due to its high mg dosage of 50-100mg per day. It also negatively affects hepatic lipase, an enzyme that can significantly reduce HDL cholesterol levels.

Increased risks of gynecomastia are of concern when taking the above cycle, due to deca durabolin increasing progesterone and anadrol increasing estrogen levels.

An AI (aromatase inhibitor) will be ineffective for treating anadrol’s estrogenic effects, as it does not aromatize, but instead directly stimulates the estrogen receptors.

SERMs such as Clomid or Nolvadex can inhibit estrogen activity from a receptor level, thus preventing gynecomastia from anadrol. However, these SERMs can also increase progesterone (5), thus increasing nandrolone-induced gynecomastia.

Some steroid-users may try and prevent gynecomastia when running this cycle, by administering an aromatase inhibitor (AI) to lower progesterone (not estrogen), however this can exacerbate cardiovascular strain due to lower levels of estrogen. Furthermore, anadrol-induced gynecomastia remains a concern even when running an AI.

Testosterone suppression will be extreme post-cycle with this stack, requiring an aggressive PCT.

Dr. Michael Scally, an expert in hormone replacement therapy, has experienced extensive success implementing a trio of medications; accelerating the recovery of anabolic androgenic steroid-induced hypogonadism (ASIH).

These are:

  • Human chorionic gonadotropin (hCG)
  • Clomiphene (clomid)
  • Tamoxifen (nolvadex)

When these three medications were given to 19 men with shut down endogenous testosterone levels; after 45 days, 100% of them had normal serum testoerone readings.

Deca Durabolin and Testosterone Cycle

Testosterone is another potent anabolic steroid, typically taken to add large amounts of muscular hypertrophy (size) and strength in the off-season

However, testosterone can also be utilized as a cutting steroid, due to its strong androgenic properties having a stimulatory effect on lipolysis; resulting in decreased adipose tissue (enhanced fat loss).

Testosterone is regarded as one of the safest anabolic steroids, being FDA approved and prescribed to many men worldwide for the treatment of TRT (testosterone replacement therapy).

Testosterone and deca durabolin can be regarded as one of the mildest stacks a bodybuilder can utilize, in regards to side effects.

However, it remains a potent duo for enhancing body composition, with users experiencing 30 plus pounds of muscle gain and amazing improvements in strength.

testosterone deca cycle

This bulking cycle does not present a massive risk for hypertension, however cholesterol changes are to be expected; causing mild increases in blood pressure. Deca durabolin and testosterone are two of the most cardiovascular-friendly steroids available.

Testosterone compliments deca durabolin exceptionally well, due to testosterone’s androgenic nature reducing the sexual side effects of deca durabolin. However, unlike anadrol, testosterone does this without compromising health in other aspects (such as the liver).

This cycle is also better suited to someone trying to prevent gynecomastia, as an aromatase inhibitor (AI) can be taken, synergistically lowering estrogen and progesterone levels.

Anastrozole and letrozole are two popular AI medications taken by bodybuilders today.

Endogenous testosterone levels will decrease dramatically, requiring a PCT and some users experiencing: hair thinning, recession, or loss on the scalp due to testosterone raising DHT (dihydrotestosterone). This cycle is less hair friendly compared to the deca durabolin/dianabol stack.

Deca Durabolin Results (Before and After Pictures)

anadrol results

This user displays amazing improvements in muscle hypertrophy and thickness after completing a deca durabolin/anadrol cycle.

In the before picture he had previously taken SARMs (selective androgen receptor modulators), therefore this wasn’t his first PED cycle.

This before and after transformation is typical of someone stacking deca durabolin with another powerful bulking steroid.Stretch marks can be seen on his right deltoid in the after photo, indicating the rapid anabolic effects of anadrol/deca.

Note: Deca-only cycles are unlikely to add this level of mass, with 20lbs of muscle being the more likely outcome (rather than 30-40lbs).

Deca Durabolin For Women

Deca durabolin is sometimes taken by women, when trying to bulk up and gain lean muscle tissue.

Although deca durabolin may not be the most optimal steroid for women (with anavar being a more popular compound), research suggests deca durabolin is relatively safe from a virilization perspective.

Studies indicate that deca durabolin is generally well-tolerated by women, when taken in dosages of 100mg (6), administered every other week for 12 weeks (thus translating as 50mg/week).

However, studies also suggest that deca durabolin is capable of causing masculinization in women, even in very small dosages, when taken long-term.

Such adverse effects occurred on a dose of 50mg, administered every 2-3 weeks. This translates as a dose of 13-25mg per week (7). Thus, if women were to take deca durabolin it would be wise to keep cycles short (preferably 8 weeks or less).

Deca Durabolin Cycle for Women

deca durabolin cycle for women

Note: Anadrol would be a more suitable bulking steroid for women, in terms of preventing virilization; with mega doses failing to produce virilization, even when taken for excessive periods of time (8).

Anadrol also is a fast-acting compound that clears out of the body quickly, whereas deca durabolin is slow-acting with a half-life of 6 days; thus making it more risky for women who begin to experience masculinization symptoms. This is because even if they stop taking deca durabolin, it will remain in their system for up to 12 days.


Deca Durabolin vs EQ (Equipoise)

Equipoise (boldenone undecylenate) is an injectable veterinary steroid, commonly given to horses to increase lean bodyweight.

EQ is a modified form of testosterone, like deca durabolin, with a double bond being introduced between carbons 1 and 2.

Bodybuilders often take equipoise as an alternative to deca durabolin, being a slightly more powerful and androgenic compound.

Equipoise is believed to be more estrogenic than deca durabolin, with EQ displaying 50% (half) of the estrogenic effects of testosterone and deca durabolin just 20%.

The general consensus is: if EQ replaced deca durabolin in various steroid cycles, the end result would be very similar.

Trenbolone vs Deca Durabolin

Trenbolone and deca durabolin are both injectable bulking steroids, yet are very different in their pharmacology and effects.

Trenbolone is more anabolic than deca durabolin, reflected in its anabolic rating of 500 vs deca durabolin’s 125.

Thus, trenbolone will add more lean muscle than deca durabolin, however weight gain at the end of a cycle may be similar; due to deca causing fluid retention and trenbolone enhancing fat loss.

Trenbolone is considered one of the most potent and harshest AAS, whereas deca durabolin is mild and FDA approved (in medicine).

Trenbolone will cause considerably more cardiac hypertrophy (enlargement of the heart) and increase the risk of atherosclerotic plaque.

Trenbolone also is very androgenic and deca durabolin is not, thus hair recession/loss on the scalp, acne vulgaris and prostate enlargement are common with trenbolone (but rare with deca durabolin).

Thus, trenbolone will have a more dramatic effect on body composition, however it will also come with more severe side effects (specifically hypertension).

Summary: Deca Durabolin Pros and Cons


  • Mild side effects
  • Effective mass-builder
  • High-tolerance among women (during short-term use)
  • Promotes joint health


  • Impotence
  • Delivery via injection (inconvenient for some users)
  • Suppressive to endogenous testosterone