Nandrolone (NPP & Deca-Durabolin)

Nandrolone is a synthetic anabolic-androgenic steroid (AAS) of the 19-nortestosterone family, with two common injectable forms: nandrolone phenylpropionate (NPP, brand name Durabolin) and nandrolone decanoate (Deca-Durabolin). Both are prohormones of nandrolone (19-nortestosterone) and act as androgen receptor agonists. Decanoate is a very long-acting ester (introduced in 1962) while NPP is shorter-acting (introduced in 1959). Nandrolone decanoate is one of the most widely used AAS worldwide for physique and performance enhancement. Compared to testosterone, nandrolone esters have strong anabolic effects and weak androgenic effects, giving them a relatively mild masculinizing profile. In bodybuilders, nandrolone is prized for lean mass gain and “filling out” muscles, often with less bulk water retention than an equivalent dose of testosterone.

Esters and Kinetics. The ester attached to nandrolone determines its half-life and injection frequency. NPP (phenylpropionate ester) has a short half-life (elimination ~2–3 days after intramuscular injection) and duration of action ~5–7 days, requiring injections every other day (EOD) or daily for stable levels. Decanoate has a much longer half-life (~6–12 days) and duration ~2–3 weeks, so typical dosing is once weekly (or twice weekly for smoother levels). In practical terms, NPP is cleared in days while Deca persists for weeks. This also affects drug testing: nandrolone decanoate can be detected for months after a cycle, whereas NPP clears faster.

Users report that nandrolone provides steady muscle gains and strength increases, often described as “full” or “thick” gains with enhanced pumps. Strength improvements tend to accumulate each week on cycle. Many note improved joint comfort and connective tissue support, possibly from increased collagen synthesis (in 19-nors) allowing heavier training. At moderate doses, users often feel energetic and even positive in mood, although higher doses can lead to pronounced side effects. Anecdotally, low-to-moderate doses of nandrolone make muscles feel unusually full and improve workout recovery. One user reported “breaking all kinds of strength PRs, looking thick” on a testosterone+deca stack.

On the flip side, some mental effects can be troubling. Nandrolone (especially Deca) is notorious for causing unusual psychological symptoms in some users: increased irritability, anxiety, and even obsessive or paranoid thoughts have been reported. For example, one user described intense jealousy and obsessive fantasies while on Deca/testosterone. Libido effects can vary: when stacked with high-dose testosterone, libido often remains high, whereas on nandrolone alone some report “Deca-dick” (reduced sex drive), likely due to suppressed testosterone or elevated prolactin. In summary, positive subjective effects include significant pumps, muscle hardness and fullness, mild joint relief, and steady strength gains. Negative subjective effects can include water retention/bloating (more with Deca), irritability or mood swings, and prolactin-related issues (see below).

Nandrolone’s side effects reflect its steroid nature. Key risks include:

Estrogenic Effects: Nandrolone aromatizes to estradiol at about 20% the rate of testosterone. Thus Deca can cause water retention and gynecomastia if estrogens are high. While many believe Deca is non-aromatizing, heavy doses can drive estrogenic effects: one user needed high-dose Arimidex to stop nipple soreness on 400 mg/week Deca. NPP being shorter-acting also aromatizes moderately, though many bodybuilders use an aromatase inhibitor (AI) like anastrozole if any sign of fluid retention or gyno appears.

Progestogenic Effects: Nandrolone has moderate progestin activity. This can potentiate estrogen-like side effects (fluid retention, breast tissue stimulation) and elevate prolactin. Clinically it is used as a progestogen. Many users experience high prolactin on Deca/NPP, leading to nipple sensitivity, lactation or gyno. To manage this, dopamine agonists such as cabergoline are commonly used on cycles containing nandrolone, since cabergoline directly suppresses prolactin with minimal side effects.

Androgenic Effects: Although nandrolone is less androgenic than testosterone, side effects like acne, oily skin and hair loss can occur in genetically susceptible individuals. Virilization (voice deepening, body hair growth) can happen, especially at high doses. However, due to 5α-reductase metabolism, nandrolone is inactivated in scalp and prostate (converted to weak 5α-dihydronandrolone). This results in a lower risk of hair loss and prostate issues than testosterone.

Lipids and Cardiovascular: Like all AAS, nandrolone can unfavorably affect cholesterol: studies are mixed. A short study (100 mg/week for 6 weeks) saw no significant change in HDL or LDL, whereas a longer, higher-dose trial (with resistance training) found an 8–11 mg/dL drop in HDL cholesterol. In general, expect some HDL suppression and possible blood pressure increases on cycle. Users should monitor lipids and blood pressure; some include supplements (fish oil, red yeast rice) to mitigate these effects.

Endocrine (HPTA) Suppression: Nandrolone powerfully suppresses the hypothalamic–pituitary–gonadal axis. In one study Deca at 100 mg/week for 6 weeks cut endogenous testosterone by 57%; at 300 mg/week, by ~70%. Recovery of natural testosterone can take many months after high-dose or long cycles. Hence Post Cycle Therapy (PCT) or longer washouts are critical. Because of its long half-life, Deca delays HPTA recovery more than shorter esters.

Other Effects: Injectable nandrolone is not hepatotoxic (not C17-alkylated), so liver enzymes usually stay normal. It can increase red blood cell production (slightly raising hematocrit). Pain or soreness at the injection site sometimes occurs. Rare serious risks (e.g. cardiotoxicity, liver tumors) are more associated with very long-term abuse.

In summary, major side effects involve estrogenic/progestogenic symptoms (water weight, gyno, prolactin issues), HPTA shutdown, and typical AAS androgenic effects. Ancillaries commonly used include AIs (e.g. anastrozole) to control estrogen, SERMs (tamoxifen) for gyno, and cabergoline/pramipexole for prolactin.

Nandrolone esters are prodrugs of 19-nortestosterone, an agonist of the androgen receptor (AR). Once injected and de-esterified, nandrolone binds AR in muscle and bone to increase protein synthesis and muscle growth. It has a higher anabolic-to-androgenic ratio than testosterone, which accounts for its strong growth effects and milder masculine side effect profile.

In tissues rich in 5α-reductase (e.g. skin, scalp, prostate), nandrolone is converted into 5α-dihydronandrolone, a weak AR ligand. In contrast, testosterone converts to much stronger dihydrotestosterone (DHT). This differential metabolism means nandrolone causes less scalp hair loss, less acne, and minimal prostate enlargement than testosterone at equivalent doses.

Nandrolone can be aromatized to estradiol, but at a low rate (~20% of testosterone’s rate). Thus, while estrogenic effects are milder, significant aromatization (and consequent water weight) can still occur, especially when combined with high doses of exogenous testosterone. Its progestogenic action (binding progesterone receptors ~20% as well as AR) also contributes to fluid retention and breast tissue effects.

Endocrine feedback: Nandrolone’s AR and progestin activity strongly suppresses GnRH and LH/FSH. Studies show marked testosterone suppression after weeks of ND use. Unlike testosterone where estradiol partly mediates HPTA shutdown, with nandrolone most suppression is direct (androgenic+progestogenic).

Pharmacokinetics: After intramuscular injection in oil, the ester dissolves as a depot and is slowly released into blood. Peak nandrolone levels occur ~1–2 days after injection, then decline over the ester’s lifespan (~1–3 weeks for Deca). Bioavailability is moderate (50–70% IM). Nandrolone is primarily metabolized in the liver via reduction, hydroxylation and conjugation, yielding metabolites (19-norandrosterone, etc.) detectable in urine. These metabolites (especially 19-norandrosterone) are the target of anti-doping tests. Small amounts of unesterified nandrolone are rapidly cleared (half-life ~hours).

Typical Doses (Men): For male athletes, common dosing is on the order of 200–600 mg/week of nandrolone decanoate for bulking cycles (often combined with testosterone). Deca injections are typically given once or twice per week. NPP dosing is often cited as 75–200 mg/week, split into EOD or ED injections (e.g. 50 mg EOD). Because of its short ester, NPP is often injected EOD. Beginners might start at the low end (e.g. 200 mg Deca/week or 100 mg NPP/week) while advanced users might go higher. Typical cycle lengths are 8–16 weeks.

Some examples: an experienced user reported running 400–600 mg/week Deca with 400–600 mg/week testosterone, yielding “thick” gains and improving every week. Another ran 500 mg Test, 500 mg EQ, 400 mg NPP (all per week) for 6 weeks and gained 12 lb of bodyweight, noting great fullness and pumps. The Reddit Steroid Wiki (for women’s context) suggests NPP at 5–15 mg/day (35–100 mg/week) for 8–10 weeks; male doses would be roughly 10× those per-body-weight.

Injection Frequency: NPP is typically injected every other day or even daily to maintain stable blood levels. Deca can be dosed weekly. A common strategy is to inject Deca on the same day(s) as long-ester testosterone (e.g. Test E/Cyp), to simplify schedules. Because Deca builds up in tissue, early cycles often “front-load” with a slightly larger first shot, though this is debated.

Women’s Use: Nandrolone is used by some female athletes at very low doses (e.g. 5–15 mg/day of NPP, or 50–100 mg/week Deca) for strength/size. However, virilization risk (voice deepening, clitoromegaly) is significant, so it is recommended only for experienced women. The shorter ester (NPP) is often preferred for women because it is easier to discontinue if side effects occur.

Post-Cycle Therapy (PCT): Because nandrolone suppresses natural testosterone for a long time, PCT timing is tricky. With Deca’s 2–3 week decline, it’s common to continue testosterone injections until nandrolone has mostly cleared (several weeks after last Deca). Then PCT with SERMs (e.g. clomid, Nolvadex) can begin. For NPP, PCT can start sooner (a week or two after the last dose) because it clears faster. Many users do not attempt PCT with a nandrolone-only cycle; instead they simply withdraw and rely on endogenous recovery (not recommended at high doses).

Bulking: Nandrolone is primarily a mass-building (bulking) steroid. It promotes lean weight gain and strength without excessive fat gain. Users often stack Deca with testosterone (the classic “Test/Deca” stack) and sometimes with other bulking steroids like Dianabol, Anadrol, or Equipoise. For example, a typical off-season bulking cycle could be 500–750 mg/week testosterone plus 300–500 mg/week Deca for 12–16 weeks.

Joint Relief: Anecdotally, many claim nandrolone relieves joint pain. It is thought to increase synovial fluid or collagen synthesis, “lubricating” joints under heavy loads. However, experiences vary. In one report, a user did not find Deca improved his elbow pain – he attributed the relief he felt on cycle purely to water retention from testosterone.

Cutting/Leanness: Nandrolone is not a classic “cutting” steroid since it can cause some water retention. However, it still promotes strength and lean mass on a mild caloric deficit. Some use lower doses (100–200 mg/week) during cutting to preserve muscle. NPP’s milder retention can make it slightly more suitable than Deca during diet phases, but few will choose nandrolone over more anti-catabolic steroids like Primobolan or Winstrol when dieting.

Stacking (Blast-Cruise or TRT): For athletes on long-term TRT, adding nandrolone is possible but not common: it requires concomitant testosterone because nandrolone suppresses libido. In a “blast-cruise” context, some users occasionally “blast” on Deca for months, but recovery is harder due to Deca’s long action. Most recommend reserving Deca for finite cycles rather than continuous use.

Detection and Sport: Because metabolites of nandrolone linger, Deca carries a long detection window. Anti-doping tests look for 19-norandrosterone; values >2 ng/mL are positive. Deca can be detected in urine for 3–6 months (and some sources say up to ~18 months) after last injection. NPP’s detection window is shorter (likely a few months) but still long compared to short esters. Competing athletes should use extreme caution.

Ancillaries: As noted, an AI and a prolactin antagonist are often on hand. Cabergoline (e.g. 0.25–0.5 mg every 3–4 days) is frequently used prophylactically or at first sign of prolactin issues. If gynecomastia occurs, SERMs (tamoxifen or toremifene) may be needed. Liver support (though less critical than for 17aa orals) and routine bloodwork are advised on long cycles.

Summary: Both NPP and Deca share the same core anabolic effects of nandrolone, but differ in pharmacokinetics and cycle logistics. NPP provides a faster but short-lived effect, suiting shorter cycles and female use. Deca builds up more slowly but endures much longer, making it favored for deep off-season bulking. Their side effect profiles are similar, though the longer activity of Deca can magnify issues (water retention, mood, HPTA suppression) and delays recovery. Users choose between them based on cycle length, injection convenience, and personal response.