Oxymetholone - Zyvex Pharmaceuticals
Oxymetholone (Anadrol) - The Most Powerful Oral Steroid for Rapid Mass
Oxymetholone by Zyvex Pharmaceuticals contains Oxymetholone at 50 mg per tablet - the compound sold under the brand name Anadrol-50. It is the most potent oral anabolic steroid by raw output, producing more mass and strength gain per unit of time than any other oral compound. Oxymetholone was first synthesized by Syntex Pharmaceuticals in 1960 and approved by the FDA for the treatment of anemia caused by bone marrow failure, aplastic anemia, myelofibrosis, and muscle wasting conditions. Its anabolic-to-androgenic ratio of 320:45 versus testosterone's 100:100 reflects the intensity of its anabolic drive relative to androgenic activity - a profile that produces exceptional muscle and strength gains at the cost of significant side effect burden that must be managed carefully.
Oxymetholone has a pharmacological profile that is unusual among oral steroids. It is a DHT-derived compound but behaves in a distinctly non-DHT manner at the estrogenic level: it does not aromatize to estrogen through the aromatase enzyme, yet it causes significant water retention, gynecomastia risk, and other estrogenic symptoms. The proposed mechanism is direct activation of estrogen receptors by the compound itself rather than through estradiol conversion. The critical practical consequence is that aromatase inhibitors do not fully control Oxymetholone's estrogenic side effects, unlike the AIs that effectively manage testosterone-driven estrogen. As a 17-alpha alkylated compound, Oxymetholone is hepatotoxic and cycle length must be strictly limited to 4-6 weeks with liver enzyme monitoring.
About the Compound
Oxymetholone was developed in 1960 by Syntex and became one of the most widely prescribed anabolic steroids in clinical medicine during the following decade, used for aplastic anemia, muscle wasting from HIV/AIDS, and osteoporosis. The original Anadrol-50 brand contained the same 50 mg per tablet formulation that remains the standard today. In bodybuilding, Oxymetholone became prominent in the 1970s and 1980s when powerlifters and bodybuilders recognized that no other oral compound could produce equivalent strength and mass gains in such a short period. The gains - while substantial and rapid - come with equally substantial side effects, which is why Oxymetholone is generally reserved for intermediate to advanced users who have experience managing the side effect profile of anabolic steroids.
Its DHT-derived structure gives Oxymetholone a fundamental difference from testosterone in the way it interacts with estrogen - it bypasses aromatase entirely, yet exhibits estrogenic activity through a direct receptor mechanism. This makes it one of the most pharmacologically complex oral steroids in terms of side effect management. The 17-alpha alkylation that gives it oral bioavailability also makes it the most hepatotoxic of the commonly used oral steroids, requiring strict cycle length limits and liver protection protocols. At 50 mg per tablet, the standard dose of one to two tablets per day provides the dose range used in both clinical applications and performance settings.
Effects and Benefits
Oxymetholone produces the fastest and most dramatic changes in mass and strength of any oral anabolic steroid. The effects are driven by its very high anabolic potency, its stimulation of erythropoiesis (red blood cell production), and the significant water and glycogen retention it causes - both of which contribute to the rapid scale weight and strength numbers.
- Rapid mass gains - Users commonly gain 4-7 kg of scale weight in the first 2-3 weeks of an Oxymetholone cycle. A significant portion of this is water and glycogen retention rather than dry muscle tissue, but actual lean mass accrual is also substantial and faster than any other oral steroid. The scale weight gains make Oxymetholone the go-to kickstart oral for powerlifters and strength athletes beginning a long bulking cycle.
- Explosive strength increases - Strength increases on Oxymetholone are uniquely rapid. Many users report their heaviest compound lifts increasing by 20-30 kg within 3-4 weeks. This is partly driven by the water retention in joints and connective tissue (acting as a mechanical cushion) and partly by the direct anabolic signaling in muscle. Powerlifters have historically used Oxymetholone specifically for this strength effect.
- Red blood cell stimulation - Oxymetholone stimulates erythropoietin production, increasing red blood cell count and oxygen-carrying capacity. This improves muscular endurance under heavy training loads and contributes to the training volume capacity increase users experience on cycle.
- Joint cushioning - The significant water retention caused by Oxymetholone, while undesirable cosmetically, provides a cushioning effect in the joints during heavy lifting. Athletes with chronic joint pain often notice significant pain relief during an Oxymetholone cycle - a secondary benefit to the primary mass and strength goals.
- Appetite stimulation - Oxymetholone increases appetite substantially, which supports the caloric surplus required for maximum mass gains. For users who struggle to eat enough to support heavy bulking, this appetite stimulation is a practical benefit.
Hepatotoxicity is the primary safety constraint on Oxymetholone use. As a 17-alpha alkylated compound, it causes significant liver stress that accumulates over time. Cycle length must be kept to 4-6 weeks maximum. A liver panel (ALT/AST) should be checked before starting, at the midpoint of the cycle, and 4 weeks after completing. Avoid all alcohol during the cycle and avoid concurrent use of other hepatotoxic compounds (oral anabolic steroids, acetaminophen in high doses, recreational drugs). TUDCA or UDCA 500 mg/day throughout the cycle provides liver support. Do not run Oxymetholone for 8 or more weeks - the risk of liver toxicity becomes unacceptable beyond the 6-week mark.
Dosing and Cycle Length
Standard Dose
The standard Oxymetholone dose for performance use is 50-100 mg per day. For most users, 50 mg/day (one tablet) produces significant gains with a more manageable side effect profile - particularly in terms of water retention, blood pressure, and liver stress. The 100 mg/day dose (two tablets) produces more dramatic gains but also substantially greater water retention, blood pressure elevation, and liver strain. Users new to Oxymetholone should always begin at 50 mg/day to assess individual response before considering higher doses. Doses above 100 mg/day produce diminishing anabolic returns while increasing side effects disproportionately.
Cycle Length
Oxymetholone cycles must not exceed 4-6 weeks due to hepatotoxicity. Most users run it for exactly 4 weeks as a cycle kickstart while a long-ester injectable compound builds to stable blood levels, then drop the oral. Some users run it for 6 weeks standalone or as a longer kickstart, but this requires strict liver monitoring throughout. After completing an Oxymetholone cycle, allow a minimum of 8-12 weeks before using any 17-AA oral anabolic steroid again - this allows liver enzymes to normalize fully.
Dosing Timing
With an 8-9 hour half-life, Oxymetholone can be dosed once daily in the morning or split into two doses (morning and early afternoon) for more stable blood levels. Taking it with food significantly reduces the gastrointestinal discomfort that many users experience on an empty stomach. Pre-workout timing is popular with some users who want the acute performance benefit during training, but the half-life is long enough that timing relative to training matters less than with shorter-acting compounds.
Use Cases
| Use Case | Cycle Setup | Notes |
|---|---|---|
| Kickstart for long-ester cycle | Oxymetholone 50 mg/day (weeks 1-4) + Testosterone Enanthate 500 mg/wk (weeks 1-14) | The most common use. Oxymetholone provides immediate mass and strength while Test E builds to stable blood levels. Drop the oral at week 4. PCT begins 14 days after last Test E injection. |
| Powerlifting strength cycle | Oxymetholone 50-100 mg/day (weeks 1-6) + Testosterone Propionate 300-400 mg/wk | Maximum strength output protocol. Oxymetholone's rapid strength effect is the primary goal. Run alongside a testosterone base to prevent low-T symptoms from suppression. |
| Standalone oral bulking cycle | Oxymetholone 50 mg/day for 6 weeks + testosterone base 200 mg/wk | Minimal testosterone to maintain function, Oxymetholone as the primary anabolic driver. Nolvadex 20 mg/day on cycle for gyno protection. PCT immediately after the 6-week oral cycle. |
| Advanced mass cycle | Oxymetholone 50 mg/day (weeks 1-4) + Testosterone Enanthate 600 mg/wk + Deca 300 400 mg/wk, 14-16 weeks | Classic advanced bulking combination. Oxymetholone kickstarts, Deca provides joint support and lean mass throughout, testosterone provides the anabolic base. Full on-cycle support required. |
Side Effects
| Side Effect | Background | Management |
|---|---|---|
| Hepatotoxicity | The most serious side effect. 17-alpha alkylation makes Oxymetholone the most hepatotoxic of the common oral steroids. Liver enzyme elevation (ALT/AST) occurs in virtually all users; peliosis hepatis and hepatocellular carcinoma have been documented with prolonged clinical use (months to years, not weeks). Short 4-6 week cycles at standard doses carry substantially lower risk than the prolonged clinical dosing that produced the most serious documented cases. | Strict 4-6 week cycle limit. TUDCA/UDCA 500 mg/day throughout. No alcohol. Liver panel (ALT/AST) before, at midpoint, and 4 weeks post-cycle. Do not combine with other 17-AA orals. 8-12 weeks minimum rest between oral cycles. |
| Gynecomastia / water retention | Oxymetholone does not aromatize to estrogen but causes estrogenic effects - including gynecomastia and significant water retention - through direct estrogen receptor activation. This means standard aromatase inhibitors (Arimidex, Aromasin) do not fully prevent these effects. Nolvadex, which blocks the estrogen receptor directly at the breast tissue level, is more effective for on-cycle gyno protection than AIs. | Nolvadex 20 mg/day on cycle for gyno protection - not an AI. Control water retention through sodium intake management. Expect significant bloat at 100 mg/day doses. |
| Blood pressure elevation | The combination of significant water retention and red blood cell increase produces substantial blood pressure elevation in most users, particularly at 100 mg/day doses. This is a meaningful cardiovascular risk that requires monitoring, especially in users with pre-existing blood pressure concerns. | Blood pressure monitoring throughout the cycle. Reduce sodium intake. Consider dose reduction from 100 to 50 mg if BP rises above 140/90. Cardiovascular exercise throughout the cycle. |
| Testosterone suppression | Oxymetholone suppresses endogenous testosterone production through HPG axis suppression, as all anabolic steroids do. The suppression is significant and requires PCT. Always run with a testosterone base to prevent low-T symptoms during the cycle. | Testosterone base at minimum 200 mg/wk during cycle. Standard PCT: Nolvadex 40/20 mg taper for 4 weeks after ester clearance. |
| Lipid changes | Oxymetholone produces severe unfavorable lipid changes - significant HDL reduction and LDL increase - among the worst of oral anabolic steroids. This compounds the cardiovascular risk alongside the blood pressure elevation. | Lipid panel before and after cycle. Fish oil supplementation. Minimize cycle duration. Prioritize cardiovascular health in the weeks following the cycle. |
| Hair loss | Despite being DHT-derived, Oxymetholone's conversion to DHT at the scalp is atypical. Hair loss risk exists for genetically predisposed users but is less pronounced than with testosterone or classic DHT-derived compounds at equivalent doses. | Nizoral shampoo for maintenance. Finasteride is not effective for Oxymetholone-driven hair loss (the mechanism differs from standard 5-alpha reductase activity). |
Oxymetholone vs Dianabol
| Factor | Oxymetholone (Anadrol) | Dianabol (Methandrostenolone) |
|---|---|---|
| Anabolic strength | Higher - produces more mass and strength per week | Strong - second only to Oxymetholone among oral bulkers |
| Mass gain speed | Fastest of any oral - 4-7 kg in 3-4 weeks common | Fast - 3-5 kg in 4-6 weeks |
| Water retention | Severe - significant bloat | Moderate - noticeable but manageable with AI |
| Estrogen management | Complex - AI does not fully work; Nolvadex preferred for gyno | Standard - AI (Arimidex, Aromasin) effectively controls estrogen |
| Hepatotoxicity | High - 4-6 weeks maximum | Moderate - 6-8 weeks tolerable |
| Side effect burden | Heavy - for intermediate to advanced users | Moderate - more manageable for intermediate users |
| Best for | Maximum mass and strength output, powerlifting, kickstart for heavy cycles | Lean bulking, first oral cycle, versatile mass and strength |
Frequently Asked Questions
What is Oxymetholone (Anadrol) and how fast does it work?
Oxymetholone by Zyvex Pharmaceuticals contains Oxymetholone at 50 mg per tablet - the compound historically marketed as Anadrol-50 by Syntex and later Unimed. It is the most potent oral anabolic steroid by output, with an anabolic-to-androgenic ratio of 320:45 versus testosterone's 100:100. Originally developed in 1960 for the treatment of anemia and muscle wasting, it entered bodybuilding use in the 1970s as powerlifters recognized its unmatched strength and mass effects. Results appear rapidly - most users notice significant strength increases within the first week and measurable mass gains by week two. By week 3-4, total scale weight gains of 4-7 kg are typical, driven by a combination of actual lean tissue accrual, water retention, and glycogen loading. No other oral anabolic steroid produces comparable results in this time frame.
Why does Anadrol cause gyno if it does not aromatize?
This is one of the most clinically important and frequently misunderstood aspects of Oxymetholone. It does not aromatize to estradiol via the aromatase enzyme - so aromatase inhibitors like Arimidex and Aromasin do not block the estrogenic mechanism responsible for Oxymetholone's water retention and gynecomastia risk. The proposed mechanism is direct activation of estrogen receptors by Oxymetholone itself, acting as a partial estrogen receptor agonist independent of aromatase. The practical consequence: if gynecomastia symptoms appear on an Oxymetholone cycle, increasing an AI dose will not fix it. Nolvadex (Tamoxifen) - which blocks the estrogen receptor directly at the breast tissue level - is the appropriate on-cycle protection and treatment. Running Nolvadex 20 mg/day throughout an Oxymetholone cycle is the standard approach for gyno prevention.
How hepatotoxic is Oxymetholone and how do I protect my liver?
Oxymetholone is the most hepatotoxic of the commonly used oral anabolic steroids. Its 17-alpha alkylation that enables oral bioavailability also stresses the liver significantly more than Dianabol or Anavar at equivalent cycle lengths. In clinical settings where it was used for months to years (for anemia and HIV wasting), cases of peliosis hepatis and, rarely, hepatocellular carcinoma have been documented. In the bodybuilding context of 4-6 week cycles at 50-100 mg/day, these extreme outcomes are not representative of the risk - but liver enzyme elevation (ALT/AST) is virtually universal and requires management. The liver protection protocol: TUDCA or UDCA 500 mg/day throughout the cycle, no alcohol, no other hepatotoxic drugs (including acetaminophen above label doses), liver panel bloodwork before starting and at the cycle midpoint. Allow 8-12 weeks minimum before running another 17-AA oral steroid after completing an Oxymetholone cycle to allow full liver recovery.
Should I take 50 mg or 100 mg of Anadrol per day?
For users new to Oxymetholone, 50 mg/day (one tablet) is always the correct starting dose. It produces substantial gains, significant strength increases, and is far more manageable in terms of water retention, blood pressure, and liver stress than 100 mg/day. Experienced users who have run 50 mg cycles successfully and want to push output further may try 100 mg/day, but should understand that the side effects scale disproportionately: water retention becomes severe, blood pressure increases significantly, and liver stress doubles. The additional anabolic gains from 100 mg versus 50 mg are real but smaller in relative terms than the doubling of side effect burden. Most bodybuilders get the best risk-to-reward profile at 50 mg/day. If you are using Oxymetholone as a kickstart oral for a longer injectable cycle, 50 mg/day for 4 weeks is almost always sufficient to achieve the kickstart goal.
Does Oxymetholone require PCT?
Yes - Oxymetholone strongly suppresses endogenous testosterone production through HPG axis suppression. Always run Oxymetholone alongside a testosterone base at minimum 200 mg/week to prevent low-testosterone symptoms during the cycle. PCT timing depends on the longest-ester compound in the cycle: if running alongside Testosterone Propionate, start PCT 3-4 days after the last injection of both compounds. If running alongside Testosterone Enanthate or Cypionate, wait 14 days after the last long-ester injection before starting PCT (the Oxymetholone has already cleared in 1-2 weeks at that point). Standard PCT: Nolvadex 40 mg/day for 2 weeks, then 20 mg/day for 2 more weeks. For heavier or longer cycles, add Clomid 25-50 mg/day in the first 2 weeks alongside Nolvadex.
How long does Oxymetholone stay in your system for drug testing?
Oxymetholone metabolites are detectable in urine for approximately 8 weeks from the last dose. This is substantially longer than the compound's 8-9 hour active half-life, because metabolites persist in the body long after the parent compound has cleared. Anti-doping laboratories test specifically for Oxymetholone and its major metabolites. Competitive athletes in tested sports should plan a minimum 8-week clearance window from the last dose to any tested competition, and should note that individual variation in metabolism can extend detection windows beyond the typical range. The 8-week figure is the commonly cited estimate based on available detection data, not a guaranteed safe window for all individuals.
What is the best Oxymetholone cycle?
The most practical and widely used Oxymetholone cycle is as a 4-week kickstart oral alongside a long-ester testosterone base: Oxymetholone 50 mg/day for weeks 1-4 alongside Testosterone Enanthate 400-500 mg/week for 12-14 weeks total. Nolvadex 20 mg/day on cycle throughout the Oxymetholone portion for gyno protection, TUDCA 500 mg/day for liver support, and an AI (Arimidex 0.5 mg every other day or Aromasin 12.5 mg every other day) for the testosterone's estrogen contribution. PCT begins 14 days after the last Testosterone Enanthate injection with Nolvadex 40/20 mg taper for 4 weeks. For advanced users wanting maximum mass output, adding Deca 300-400 mg/week to this base gives the classic off-season bulking stack that bodybuilders have used for decades.
Oxymetholone vs Dianabol - which is better for mass?
Oxymetholone produces more total mass and strength gain in the same time frame than Dianabol at standard doses. A 4-week Oxymetholone cycle at 50 mg/day typically produces more scale weight and more strength increase than a 4-week Dianabol cycle at 30-40 mg/day. However, "more" does not mean "better" in this context: the additional mass from Oxymetholone is largely water and glycogen, the side effect burden is substantially heavier, estrogen management is more complex (Nolvadex rather than AI), and hepatotoxicity is more severe. Dianabol is the better choice for first-time oral steroid users, for users who want leaner gains with manageable water retention, and for users who want to run the oral portion for 6-8 weeks rather than 4-6 weeks. Oxymetholone is the right choice when maximum output in minimum time is the goal, for powerlifting strength cycles, and for experienced users who have managed Dianabol and want to progress to the most powerful oral available.
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