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Arimistane

Also known as: Androsta-3,5-diene-7,17-dione, Androst-3,5-diene-7,17-dione, 3,5-Androstadiene-7,17-dione, ATD (loosely, but chemically distinct from the banned research compound 1,4,6-androstatriene-3,17-dione)

1
1 · Natty510 · Enhanced

Lower numbers = closer to natural. Higher numbers = more enhanced.

Why this rating?

Arimistane is an over-the-counter steroidal androstadienedione marketed as an aromatase inhibitor for estrogen control and post-cycle use. Aromatase inhibitors do not build muscle, burn fat, or raise anabolic hormones directly; they only lower estrogen, a side-effect-management tool, not a physique enhancer. It does not move the natural muscular/physique ceiling by any path, so it is rated 1 (basically natty, no enhancement effect on the scale).

Overview

Arimistane (androsta-3,5-diene-7,17-dione, CID 150910, CAS 1420-49-1) is a steroidal androstadienedione sold over-the-counter as a supplement and marketed as an aromatase inhibitor for controlling estrogen and for post-cycle therapy. It belongs to the steroidal (irreversible, "suicidal") class of aromatase inhibitors by structure. It is popular precisely because it is marketed as a legal, OTC estrogen-control option, but the FDA disputes that framing (it has issued warning letters stating the ingredient does not meet the legal definition of a dietary ingredient), and it is far less studied and generally regarded as weaker/less predictable than pharmaceutical AIs like anastrozole, letrozole or exemestane.

Important Warnings

  • •The FDA has stated in warning letters that Androsta-3,5-Diene-7,17-Dione does not meet the legal definition of a dietary ingredient and is an unapproved new/prescription drug, despite being sold as an OTC "supplement"
  • •Explicitly named and prohibited at all times under WADA S4.1 (Aromatase Inhibitors), not safe for tested athletes
  • •As an unregulated OTC product, labeled dose and actual content can differ; do not assume label accuracy
  • •Do not combine with another aromatase inhibitor. Stacking AIs risks crashing estrogen
  • •Crashed estrogen (joint pain, low libido, flat mood, lethargy) is a bigger practical risk than "too much" estrogen for most users, dose to bloodwork, not by feel

Purpose & Use Cases

Estrogen Control

Marketed to lower estrogen and reduce estrogenic side effects (bloat, gynecomastia risk), as an OTC option, typically for milder estrogen management.

Post-Cycle Therapy (Community Use)

Used in OTC PCT protocols with the goal of reducing estrogen and nudging the HPTA to rebound. Evidence for this is anecdotal rather than clinical.

Prohormone/Designer-Supplement Add-On

Frequently bundled into OTC prohormone stacks as the estrogen-management component.

Benefits

  • Legal, over-the-counter aromatase inhibitor option
  • Steroidal ("suicidal"/irreversible) AI class by structure
  • Used for milder estrogen control and OTC PCT
  • Cheaper and more accessible than pharmaceutical AIs

Good to Know

It is sold as an OTC supplement, but the FDA disputes that it legally qualifies as one

Arimistane is marketed as a dietary supplement, not an FDA-approved drug. However, the FDA has issued warning letters (e.g. to Performance Nutrition Formulators/VMI Sports in 2018) stating that Androsta-3,5-Diene-7,17-Dione does not meet the legal definition of a "dietary ingredient" and is instead an unapproved new drug that, given its class (aromatase inhibitor), the agency considers unsafe for use without a prescriber's supervision. It is chemically a steroidal androstadienedione (CAS 1420-49-1) in the same irreversible/"suicidal" AI class as exemestane, but it has essentially no human clinical trial data on efficacy and is generally considered weaker and less predictable than anastrozole, letrozole or exemestane.

"Suicidal" aromatase inhibitor: what that means

Steroidal aromatase inhibitors bind the aromatase enzyme permanently (a covalent, deactivating bond), so the enzyme is destroyed rather than just blocked, hence "suicidal" or irreversible. Non-steroidal AIs (anastrozole, letrozole) instead bind reversibly. This is a class property of steroidal AIs; how strongly arimistane itself achieves it in humans is not well documented.

The DHEA-metabolite framing looks like a lab artifact, not a true metabolite

Arimistane is widely marketed as a metabolite/derivative of 7-keto-DHEA (7-oxo-DHEA). A 2021 anti-doping laboratory study (Martínez Brito et al., Drug Testing and Analysis) investigated this directly and found that arimistane forms from 7-oxo-DHEA mainly through chemical degradation during sample handling/analysis (solvent and heat-driven breakdown), not through genuine metabolic biotransformation in the body. Human liver microsome incubations showed no meaningful conversion. It remains a useful urinary marker of 7-oxo-DHEA use for anti-doping labs, but the "natural DHEA metabolite" marketing framing is not well supported as an in-vivo pathway.

Different compound from research-chemical "ATD"

Arimistane (androsta-3,5-diene-7,17-dione) is sometimes loosely called "ATD" in bodybuilding forums, but it is chemically distinct from 1,4,6-androstatriene-3,17-dione. The compound scientists actually call ATD, which was sold in supplements until it was effectively removed from the market around 2009 and is a possible boldenone-related contaminant. Don't assume research on one applies to the other.

Dosage Guidelines

Experience LevelDosage Range
Beginner25 – 50 mg/day
Intermediate50 – 75 mg/day
Advanced75 – 100 mg/day
Frequency
Once or twice daily (oral): community guides commonly split into two doses (e.g. morning/evening) on the assumption of a short half-life, though that has not been formally characterised.
Typical Cycle Length
2 – 8 weeks
Notes

These ranges reflect common supplement/community dosing, NOT clinical trial data. Arimistane has no established human pharmacokinetics or validated dosing. A frequently cited community PCT pattern is a short taper, e.g. ~75mg/day for the first 1-2 weeks stepping down to ~50mg/day then ~25mg/day over a 2-4 week course; some "on-cycle" estrogen-control protocols run longer, up to ~8 weeks. Because it is an OTC supplement, actual content and purity vary by product. As with any AI, crashing estrogen too low causes its own problems (see side effects). Bloodwork is the only reliable way to guide dosing.

Half-Life

Not well characterised in humans; community guides assume a short half-life, but this has not been formally established.

Side Effects

Low-estrogen symptoms

common
Severity
2/5

Over-suppressing estrogen causes joint aches/dryness, low libido, low mood, fatigue and lethargy, the classic "estrogen crash".

Mitigation

Use the lowest effective dose and titrate to bloodwork rather than by feel; back off if symptoms appear.

Lipid / cardiovascular strain

uncommon
Severity
2/5

Low estrogen is generally unfavourable for cholesterol/HDL, a concern shared by aromatase inhibitors as a class.

Mitigation

Do not run an AI you do not need; monitor a lipid panel.

Sourcing / purity risk

common
Severity
2/5

As an unregulated OTC supplement, dose accuracy and purity are not guaranteed.

Mitigation

Buy from reputable brands; do not assume label dose is accurate.

General Mitigation Strategies

The biggest practical error is crashing estrogen. Estrogen is needed for libido, mood, joints and lipids, so an AI should be dosed to bloodwork and only used when estrogen is genuinely high, not preventively. Being an OTC supplement, product quality is variable.

Support Supplements

Ancillary supplements commonly run alongside Arimistane to manage side effects, support the target tissue, or fill nutrient demands it creates.

Omega-3 fish oil

Suppressing estrogen is generally unfavourable for lipids/HDL, a class effect shared by aromatase inhibitors. Omega-3s support triglycerides and general cardiovascular health as a hedge, though this reasoning is extrapolated from the AI class rather than an arimistane-specific study.

Dose
2-4 g/day EPA+DHA
Timing
With meals
When
More relevant the longer and higher-dose the run, and if bloodwork shows estrogen is being suppressed hard.

Vitamin D3 + K2 / adequate calcium

Estrogen supports bone mineral density; chronic over-suppression can reduce it. Bone-support nutrients are a sensible hedge, again reasoning from AI-class pharmacology rather than arimistane-specific trial data.

Dose
Vitamin D3 to a healthy blood level; K2 and dietary calcium
Timing
Daily
When
Mainly relevant with longer or repeated courses, not a single short PCT burst.

Post Cycle Therapy (PCT)

✓PCT Not Required

Arimistane is itself often used as (or within) an OTC PCT to lower estrogen and encourage HPTA rebound. It does not require its own PCT. It is not a substitute for proper SERM-based PCT after suppressive anabolic cycles.

How It Works

Arimistane is a steroidal androstadienedione. Steroidal aromatase inhibitors (the class also containing exemestane) act as "suicidal" inhibitors. They form a permanent, deactivating covalent bond with the aromatase enzyme, irreversibly blocking the conversion of androgens to estrogen. This is contrasted with the non-steroidal AIs (anastrozole, letrozole) which bind the enzyme reversibly. Note: the general steroidal-AI mechanism is well established, but published human pharmacology for arimistane specifically is minimal, its AI activity rests largely on structural class and supplement-industry data rather than clinical trials.

Fundamentals

Reference on the practices relevant to Arimistane: how they are done and where they go wrong. Not a recommendation to use it.

Bloodwork: what to measure and when→

The markers that matter here

Warning signs & when to seek care→

When to stop and get help

Common Stacks

  • Sometimes bundled into OTC "PCT support" combos alongside a SERM, arimistane targets estrogen, the SERM targets the HPTA restart; it does not replace the SERM
  • Do not stack with a pharmaceutical AI (anastrozole, letrozole, exemestane). Pick one aromatase inhibitor, not several
  • A pharmaceutical AI dosed to bloodwork is the more controllable option when precise, reliable estrogen management is needed

WADA Status

⛔Prohibited by WADA
Category: S4. Hormone and Metabolic Modulators (Aromatase Inhibitors)
In-Competition: ProhibitedOut-of-Competition: Prohibited

Aromatase inhibitors are prohibited at all times under WADA class S4. Arimistane is explicitly named by its chemical name, "Androsta-3,5-diene-7,17-dione (arimistane)", in the S4.1 example list on the current WADA Prohibited List (verified directly against the 2026 list), alongside anastrozole, letrozole, exemestane, formestane and testolactone.

References

Last updated: July 19, 2026