Nandrolone
Also known as: deca, npp, deca-durabolin
The 'deca' steroid, known in gyms for joint comfort claims and for one of the longest detection windows of any compound.
Legal status: UK: Class C controlled drug and prescription-only medicine. Supplying it (including to friends) and importing it by post are criminal offences; personal possession for your own use generally is not. Checked 2026-07-26.
Prohibited in sport: Yes — on the WADA Prohibited List.
Approved medical use: Has been licensed in some countries for osteoporosis and for anaemia of chronic kidney disease; largely superseded by better treatments.
What it is
Nandrolone is a 19-nortestosterone: testosterone with one carbon removed, which reduces its androgenic activity relative to its anabolic activity. It has genuine medical history in treating wasting and anaemia, and it is strongly associated in fitness culture with relief of aching joints.
Where it remains licensed it is used under supervision for conditions such as the anaemia of chronic renal failure, at levels far below performance use and with monitoring attached.
What’s claimed
- Steady lean mass gain with less water retention than testosterone
- Relief of joint pain and 'lubrication' of the joints
- Better recovery between hard sessions
What the evidence shows
That nandrolone increases lean body mass in clinical populations is well-supported (Gold). The joint-comfort claim is much weaker: it has a plausible mechanism in increased collagen synthesis and fluid retention within the joint, but it is largely anecdotal at performance levels, and masking joint pain while training heavily is a route to injury rather than a benefit. Nandrolone is also known for a metabolite that remains detectable for many months, which has generated a long history of anti-doping cases.
The risks
- Endocrine: suppression of the body's own testosterone production, with testicular atrophy and impaired fertility. Recovery is not guaranteed and can be slow or incomplete.
- Sexual: nandrolone is notably associated with erectile dysfunction and loss of libido, sometimes persisting after use stops; the effect that gave rise to the gym term 'deca dick'.
- Progestogenic: activity at the progesterone receptor can produce gynaecomastia that responds poorly to the usual oestrogen-directed approaches.
- Lipids: marked lowering of HDL ('good') cholesterol and raising of LDL, an adverse cardiovascular shift that is more pronounced with oral compounds.
- Psychiatric: mood disturbance and depression, particularly on withdrawal.
What needs monitoring
- Full blood count, including haematocrit and haemoglobin
- Lipid profile
- Blood pressure
- Liver and kidney markers
- Testosterone and the wider hormonal axis: a doctor is the right person to arrange these tests and to interpret what they show.
Sources
- NHS. Anabolic steroid misuse — health risks and the law.
- GOV.UK. Controlled drugs: Misuse of Drugs Act 1971 drug classes.
- World Anti-Doping Agency. The Prohibited List.
- Pope HG, et al. Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement. Endocr Rev. 2014;35(3):341-375.