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Nandrolone decanoate

Anabolic-androgenic steroid, esterified testosterone derivative with additional progestogenic effect · Deca-Durabolin, nandrolone decanoate, Deca, nandrolone

Nandrolone decanoate is an anabolic-androgenic steroid, a close relative of testosterone, first synthesized in 1950 and used in medicine as the decanoate since 1962. It is not a gray-market substance but a medicine, approved for example in Austria, the Netherlands and Switzerland; in Germany no product is currently on the market. The effect is undisputed — and precisely the data that show it have made its indications disappear step by step.

In short

Nandrolone works, and that is established: it builds tissue and stimulates the formation of red blood cells, with a favorable ratio of anabolic to virilizing effect. That is why it was used medically, among other things for anemia due to chronic kidney failure and for osteoporosis after menopause. But over 64 years it also became just as visible what it costs: with abuse, weaker pumping performance of the heart and more deposits in the coronary arteries, fluid retention up to heart failure in people with pre-existing conditions, shut-down of the body’s own hormone production and, in women, a voice change that can remain with prolonged treatment. The indications were not removed because the effect was lacking, but because the balance no longer added up. With this substance, the question is never whether it works, but what it costs and for what.

What it is

Nandrolone is an anabolic-androgenic steroid and thus a close relative of testosterone. It was first produced in 1950, entered medicine as the decanoate in 1962, and its best-known brand name is Deca-Durabolin. Unlike almost everything else in this field, it is not a gray-market product but a medicine with approval and quality requirements, approved for example in Austria, the Netherlands and Switzerland; in Germany no product is currently on the market.

Today it is approved mainly for severe osteoporosis after menopause, and in the Netherlands also for anemia due to renal insufficiency and for aplastic anemia. The list used to be long: in 1991, a commission at the German Federal Health Office found no sufficient proof of efficacy for 17 indications advertised at the time. This list is considerably shorter today, and how it became shorter is the real story of this substance.

How it is supposed to work

Nandrolone acts on the same receptor as testosterone and essentially does the same thing: it builds tissue and stimulates the formation of red blood cells. People gained weight and felt stronger — in the early years, that was the visible part.

Two peculiarities come on top. First, the ratio of anabolic to virilizing effect is favorable — the reason it was used medically at all. Second, nandrolone also has a progestogenic effect, which shows up as fluid retention and breast growth in men.

Why the list became shorter

In the 1960s, use was broad: after operations, for burns, for frailty in old age, even for growth disorders in children. From the 1970s, the indications were narrowed step by step.

The reason is not that the effect disappeared. It stayed the same. What changed was the knowledge of the costs: in the 1960s, people mainly saw what the substance can do; the harms were only properly documented later. In addition, better agents became available for the same purposes. Sales were discontinued in many countries.

The counter-pattern

For almost all substances of this kind, the answer to the question of effect is: unclear. Here it is: established, for 60 years, undisputed. And yet for most people the answer is no.

For someone with chronic kidney failure and anemia, the calculation can be worthwhile. For a healthy thirty-year-old who wants a few kilos of muscle, the same substance is a completely different calculation — not because it works differently, it works exactly the same, but because there is nothing on the other side of the scale that outweighs the strain on the heart and blood vessels, the shut-down hormonal axis and the other side effects.

Whether it works is therefore never the last question. It is the first. The last one is: what does it cost, and for what? That is not a contradiction; that is medicine.

If someone is considering it anyway

Three points, without finger-wagging. The first concerns fertility: the body’s own production recovers in most people, but in some only after months or years, and the summary of product characteristics mentions reduced sperm production. Anyone who wants children should consider this first.

The second concerns supervision. Secretly, without monitoring and from an internet source is the constellation in which manageable risks turn into harm.

The third concerns the product. What comes from the internet is not what was studied in the trials: in a Dutch analysis, only 47 % of black-market samples contained the declared substance, and at the Zurich testing service 52 % were counterfeit.

What is well supported

Here, for once, we are not complaining about missing data. The anabolic effect, the stimulation of blood formation and the favorable ratio of anabolic to virilizing effect have been described for decades and were robust enough for approval. The other side is just as well documented: fluid retention up to heart failure in people with pre-existing conditions, rare liver function disorders, the shutdown of the body’s own production, dependence and the voice change in women are in the summary of product characteristics because they were observed in many people over 60 years; for long-term steroid abuse, weaker pumping performance and more deposits in the coronary arteries have also been measured. Both sides come from the same body of data.

What the studies show

Approval for anemia due to chronic kidney failure

Nandrolone stimulates the formation of red blood cells and was therefore used for renal anemia. The basis is clinical data from the time of approval. In 29 dialysis patients, lean body mass increased by 4.5 kg over six months in a double-blind study, compared with 1.9 kg under placebo; grip strength did not change (Johansen 1999). A meta-analysis of 20 randomized trials in 2026 found on average 1.6 kg more lean mass, without an established effect on grip strength (Prokopidis 2026).

Approval for osteoporosis after menopause

The second indication still in place today, based on the anabolic effect on bone. A review of 7 randomized trials with 293 women found fewer fractures and less bone pain (Câmara 2025).

Former indications and their withdrawal

In the 1960s, nandrolone was given after operations, for burns, for frailty in old age and for growth disorders in children. From the 1970s, this was withdrawn step by step. The process is itself a finding: it rests on better alternatives and on harms that had become known, not on a lack of effect.

Summary of product characteristics and studies on the heart

The summary of product characteristics mentions fluid retention with or without heart failure in pre-existing heart, kidney or liver disease. For long-term steroid abuse in general, an American study found lower pumping performance (ejection fraction 52 versus 63 %) and more deposits in the coronary arteries (Baggish 2017).

Six decades of observation in use

The documented harms come from long-term use: suppression of the body’s own testosterone production, virilization in women with a voice change that can remain with prolonged treatment, and rare, mild liver function disorders up to peliosis hepatis, especially at high doses. Liver tumors and severe cholestasis are described mainly for oral, 17α-alkylated steroids, to which nandrolone does not belong.

What remains open despite six decades

What is open is not the effect but the calculation for healthy people. There are no data weighing benefit and harm over years in a healthy person who wants to build muscle — the approval data come from sick people with a specific deficiency.

Status, approval and legal

Nandrolone decanoate is a prescription-only medicine, best-known brand name Deca-Durabolin. In Germany no product is currently on the market; it is approved in Austria, the Netherlands and Switzerland, among others, mainly for severe osteoporosis after menopause. The indications have been narrowed considerably since the 1970s. What is traded outside the pharmacy and prescription is gray-market goods: in a Dutch analysis, only 47 % of samples contained the declared substance, and at the Zurich testing service 52 % were counterfeit. In Germany, nandrolone is listed in the annex of the Anti-Doping Act; acquiring and possessing it in non-small quantities for doping is prohibited. In sport it is on the prohibited list and is one of the best-known doping agents of all.

Safety

Heart and blood vessels: with long-term steroid abuse, lower pumping performance and more deposits in the coronary arteries have been measured; the summary of product characteristics mentions fluid retention with or without heart failure in pre-existing heart, kidney or liver disease. Liver: for nandrolone, the summary of product characteristics mentions rare, mild liver function disorders up to peliosis hepatis, that is, blood-filled cavities, especially at high doses; liver tumors and severe cholestasis are described mainly for oral, 17α-alkylated steroids. Hormonal effects in men: the body’s own testosterone production shuts down, the testicles shrink, the sperm count falls, erectile dysfunction has been described, plus fluid retention and breast growth. In women: menstrual disorders, increased hair growth on the face and body, male-pattern hair loss, enlargement of the clitoris — and the change in voice, with hoarseness as the first sign, which can remain with prolonged treatment. Psychological: mood swings, irritability, aggressiveness and depression; according to the summary of product characteristics, use can lead to dependence and withdrawal symptoms. Before any step, a conversation with a doctor belongs here — not as a formality, but because of consequences that can be permanent.

BK-Score Well supported

Human evidence8
Mechanism9
Safety data9
Hype gap6
Track record of use9

Evidence 8, because nandrolone is approved on the basis of clinical data for specific indications — renal anemia, osteoporosis after menopause — and the anabolic effect has been undisputed for 60 years; the top score is withheld because the purpose asked about here, muscle building in healthy people, is not an approved indication. Mechanism 9, because the chain of action in humans is known and quantified, down to the favorable ratio of anabolic to virilizing effect and the additional progestogenic effect. Safety 9, because 64 years of approval and observation have produced a detailed harm profile, from edema with or without heart failure in pre-existing disease to rare liver function disorders to the voice change that can remain with prolonged treatment — a high number here means well studied and explicitly not harmless. Hype 6, because the promised effects are real, but the harm side is regularly missing in trade outside medicine; use 9, because the substance has been used under medical supervision since 1962, although the indications have been narrowed since the 1970s and sales discontinued in many places.

The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)

Frequently asked questions about nandrolone decanoate

Does nandrolone really work?

Yes, and that is the difference from most substances in this field. The anabolic effect and the stimulation of blood formation have been established and undisputed for 60 years. The open question is not the effect but the price.

Why was it then removed from so many indications?

Because the balance no longer added up. From the 1970s, better agents became available for the same purposes, and at the same time the harms were properly documented. So it was not removed for lack of effect, but because the price was too high.

What is the difference between a patient and a healthy user?

The substance works the same way in both cases. In chronic kidney failure with anemia, there is a real health gain on the other side of the scale. For a healthy person who wants muscle, there is nothing there that outweighs the strain on the heart and blood vessels, the shut-down hormonal axis and the other side effects.

Which side effect is permanent?

In women, the change in voice can remain with prolonged treatment; hoarseness is often the first sign. The body’s own hormone production also recovers in most people, but in some only after months or years.

What happens after stopping?

The body’s own production is still at rock bottom while the supplied hormone is gone. In most people the hormonal axis recovers; in some this takes months or years. The summary of product characteristics also mentions dependence and withdrawal symptoms. Of the lean body mass gained during a cycle, only part remained three months after stopping in one study: 1.2 of 4.4 kg.

Is nandrolone banned in sport?

Yes. It is on the prohibited list and is one of the best-known doping agents of all. In Germany, the Anti-Doping Act also prohibits acquiring and possessing it in non-small quantities for doping.

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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-10-09.