Deca Durabolin (Nandrolone): The Ultimate Guide

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

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 two 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 1970s, 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.

Disclosure: We do not accept any form of advertising on Inside Bodybuilding. We monetize our practice via doctor consultations and carefully chosen supplement recommendations, which have given our patients excellent results.

Best Deca Durabolin Source


If you suffer from anemia or osteoporosis and require Deca Durabolin for medicinal purposes, we recommend Prestige Pharmaceuticals due to their product efficacy and fast worldwide shipping (2–6 days).

Deca Durabolin is legal to purchase in some countries and not in others; thus, it is the responsibility of users to act within the confines of their native law.

Inside Bodybuilding does not condone the use of AAS via illegal means or for cosmetic use.

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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 by 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) in our experience, such as Anadrol, Dianabol, Superdrol or Trenbolone.

However, some of our bodybuilding patients 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.

We have also found Deca Durabolin to increase collagen synthesis, improving the health of ligaments and tendons. This is particularly beneficial to bodybuilders and powerlifters who regularly lift heavy weights, thus making them more susceptible to injury.

Joint Anti-Inflammatory

Deca Durabolin also promotes fluid retention, which aids in lubricating the joints.

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 the potent anti-inflammatory effects of the steroid. This also correlates with our anecdotal findings.

No Hepatotoxic Effects

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

If abused, we have seen orals 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 based on our LFTs (liver function tests).

Long Esters

Deca Durabolin is a slow-acting steroid containing long esters; hence, 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 bloodstream (to minimize side effects), this is largely beneficial.

Furthermore, when Deca Durabolin is stacked with other steroids, we find users continue to experience 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 very mild, based on our lipid profile testing.

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) in our experience.

Deca Dick

Deca Durabolin is infamous for its sexual side effects, including a decrease in 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 androgenicity. Androgenic steroids facilitate nitric oxide production, which is crucial in supplying blood flow to the penis. Thus, we often see Deca Durabolin compromising 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, our patients have had success in combating 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.

We have also found that supplementing with cabergoline (when taking Deca), due to its prolactin-lowering effects, can reverse the symptoms of Deca Dick.

Low Testosterone

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

We often have success stimulating endogenous testosterone production after Deca Durabolin cycles by utilizing a PCT involving Tamoxifen (Nolvadex) or/and Clomiphene (Clomid).

Estrogen and Progesterone

Deca Durabolin has low estrogenic properties, with just a 20% aromatization rate of testosterone. However, we find that Deca Durabolin users can often experience estrogen-like side effects due to its 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, we have found anti-estrogens (such as anastrozole) to be effective inhibitors of progesterone receptor expression and thus reduce the risk of gynecomastia in our patients (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 and liver enzyme activity. However, in Deca Durabolin’s case, stacking it with other steroids can actually help to mitigate negative effects regarding sexual health.

Thus, Deca Durabolin-only cycles are seldom used by our experienced bodybuilding patients in a bid to keep androgen levels high, preventing 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 in our experience are hypertension and liver toxicity. Thus, by stacking Dianabol with Deca Durabolin, users will not be greatly 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.

We have seen this stack add 30–40 pounds of weight gain to users, accompanied by 50–70 pounds of increased strength on compound lifts.

Some of the weight gained will be in the form of water, thus bloating and water retention are 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. However, we find that AIs can exacerbate blood pressure, so this is not something we recommend.

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 Anadrol’s androgenicity.

We have seen Anadrol 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, by itself, has the power to cause hypertension due to its high dosage of 50-100mg per day. We also find Anadrol anadrol affects hepatic lipase, an enzyme that, when stimulated, 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 Anadrol does not aromatize but instead directly stimulates the estrogen receptors.

SERMs such as Clomid or Nolvadex can inhibit estrogen activity at the receptor level, thus preventing gynecomastia from Anadrol. However, these SERMs can also increase progesterone (5), thus increasing nandrolone-induced gynecomastia with this stack.

Some steroid users may try to prevent gynecomastia when running this cycle by administering an aromatase inhibitor (AI) to lower progesterone (not estrogen). However, we find this exacerbates 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 testosterone readings.

We have also had much success in utilizing this PCT stack in our hypogonadal patients.

Deca Durabolin and Testosterone Cycle

deca durabolin testosterone bottles
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, which have a stimulatory effect on lipolysis, resulting in decreased adipose tissue (enhanced fat loss).

Testosterone is one of the safest anabolic steroids, in our experience, 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 two 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, which reduces the sexual side effects of Deca Durabolin. However, unlike Anadrol, Testosterone does this without compromising health in other aspects (such as the liver).

We find this cycle better suited to someone worried about gynecomastia, as an aromatase inhibitor (AI) can be taken, synergistically lowering estrogen and progesterone levels.

Anastrozole and letrozole are two popular AI medications that our patients utilize.

Endogenous testosterone levels will decrease dramatically, requiring a PCT. Some users can experience hair thinning, recession, or loss on the scalp due to testosterone-raising DHT (dihydrotestosterone). This cycle is less hair-friendly in our experience 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.

We find that 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 and Deca.

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

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. We have also found this to be true anecdotally.

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 50 mg/week).

However, studies and our own findings suggest that Deca Durabolin is capable of causing masculinization in women, even in very small dosages, when taken over the long term.

In medical literature, adverse effects have occurred at a dose of 50mg, administered every 2–3 weeks. This translates to a dose of 13–25 mg 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 cause masculinization even when taken for excessive periods of time (8).

Anadrol is also a fast-acting compound that clears out of the body quickly, whereas Deca Durabolin is slow-acting with a half-life of 6 days, making it riskier 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 body weight (9).

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

We have seen bodybuilders take equipoise as an alternative to Deca Durabolin, which is a slightly more powerful and androgenic compound.

We believe Equipoise to be more estrogenic than Deca Durabolin, with EQ displaying 50% (half) of the estrogenic effects of testosterone but 400% more than Deca Durabolin.

We find that when EQ replaces Deca Durabolin in various steroid cycles, the end result is often very similar.

Trenbolone vs. Deca Durabolin

Trenbolone and Deca Durabolin are both injectable bulking steroids, yet they are very different in their pharmacology and effects.

We find Trenbolone to be more anabolic than Deca Durabolin, which is 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 (10).

Based on our testing, we consider Trenbolone to be 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 in our experience (11).

Trenbolone is also very androgenic, while Deca Durabolin is not; thus, hair recession or loss on the scalp, acne vulgaris, and prostate enlargement are common complaints 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

deca durabolin alternative

  • 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

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