Exemestane (Aromasin) — Dosing, Cycles, Half-Life & Side Effects
Exemestane (Aromasin) is an aromatase inhibitor with a half-life of 8.9 hours in men (Mauras 2003, PMID: 14671195); 27 hours is the postmenopausal-women figure on the FDA Aromasin label and remains in the engine PK block (pk.halfLifeHours) pending a separate golden-file review.. Irreversible (suicide) aromatase inhibitor for estrogen control. This page is educational harm-reduction reference compiled from peer-reviewed literature — not medical advice, not an endorsement, not a recommendation to use. Consult a licensed clinician before any decision.
Quick Facts
| Class | Aromatase Inhibitors |
|---|---|
| Half-life | 8.9 hours in men (Mauras 2003, PMID: 14671195); 27 hours is the postmenopausal-women figure on the FDA Aromasin label and remains in the engine PK block (pk.halfLifeHours) pending a separate golden-file review. |
| Elimination half-life (free hormone) | 8.9 hours (healthy young males ages 14-26, 25mg PO daily x 10 days; Mauras et al. 2003 J Clin Endocrinol Metab, PMID: 14671195) |
| Detection window | 5 days |
| Hepatotoxicity | Low |
| Suppression | 0/10 |
| Administration | oral |
| US regulatory status | fda-approved |
Typical Dosing Ranges
Common dose range: On-cycle: 12.5mg EOD or 25mg E3D (community standard for AI-in-men). FDA-labelled adjuvant breast-cancer dose is 25mg/day — using daily in men on testosterone risks crashing estradiol.
Cycle length: As needed
Time to steady state: ~2 days
Clinical (FDA-labelled): 25mg once daily — FDA-labelled adjuvant breast-cancer dose for postmenopausal women. Daily dosing in men on testosterone over-suppresses estradiol.
On-cycle (community-reported): 12.5mg EOD or 25mg E3D — community-standard estradiol management on aromatizing cycles
Rescue / acute management: 12.5-25mg short-course for active gyno reversal; re-test E2 weekly and discontinue when symptoms resolve.
Exemestane is a steroidal suicide inhibitor — once a molecule binds aromatase, the enzyme is permanently inactive and the body must synthesize new enzyme (~3 day turnover). This is why exemestane has no rebound. Wave B.1.5 (2026-04-18) reconciled engine pk.halfLifeHours from 27h (postmenopausal-women figure on FDA Aromasin label) to 8.9h (men, Mauras 2003 PMID 14671195) — affects PCT timing math; see git history for golden-file diff review.
Dose ranges are compiled from published pharmacokinetic studies and community-reported usage. Where a value is community-reported rather than clinically studied, this page and its structured data flag it. Lower end of any range is always the safer starting point.
Stacking Considerations
- No structural stacking blockers. Standard harm-reduction rules apply: minimize total androgen load, minimize oral exposure, and monitor bloodwork.
PCT Requirements
- Depot clearance estimate: ~2 days post-last-dose before SERM start (5 × apparent depot half-life of 8.9h).
- Never stack two SERMs. Extend a single SERM (tamoxifen OR enclomiphene/clomiphene) rather than combining.
- Use the cycle planner to generate a full protocol based on your complete stack, not this compound alone.
Side Effect Profile
- Easy to crash estradiol if used at the BC dose
- Joint pain at therapeutic doses
- Expensive
- Must be taken with a fat-containing meal for absorption
Known Interactions
Exemestane (Aromasin) + Anastrozole (Arimidex)
moderate — pharmacokineticStacking two AIs is unnecessary and risks estrogen crash.
Recommendation: Use only one AI. Switch, dont stack.
Monitor: Estradiol
Related compounds
Monitoring (Bloodwork & Vitals)
- Comprehensive metabolic panel (baseline, mid-cycle, post-cycle)
- Lipid panel (total cholesterol, HDL, LDL, triglycerides)
- CBC (hemoglobin, hematocrit — watch for erythrocytosis)
- Sex-hormone panel (Total T, Free T, Estradiol sensitive, SHBG, LH, FSH)
- Blood pressure (weekly self-check; flag systolic >140 or diastolic >90)
Baseline bloodwork is recommended before any cycle. Discontinue if liver enzymes exceed 3× upper limit of normal or if hematocrit exceeds 54%.
Frequently Asked Questions
What is the half-life of Exemestane (Aromasin)?
Exemestane (Aromasin) has a half-life of approximately 8.9 hours in men (Mauras 2003, PMID: 14671195); 27 hours is the postmenopausal-women figure on the FDA Aromasin label and remains in the engine PK block (pk.halfLifeHours) pending a separate golden-file review.. Clearance estimate: 8.9h × 5 = 44.5h ≈ 1.85 days (Mauras 2003 PMID 14671195, men). The 27h figure on the FDA Aromasin label is the postmenopausal-women clinical PK package and is not appropriate for male PED-context cycle math.. This figure is used to determine injection frequency (for esters) and post-cycle clearance timing.
What is the typical dose range for Exemestane (Aromasin)?
Commonly reported ranges for Exemestane (Aromasin): On-cycle: 12.5mg EOD or 25mg E3D (community standard for AI-in-men). FDA-labelled adjuvant breast-cancer dose is 25mg/day — using daily in men on testosterone risks crashing estradiol.. Cycle length: As needed. These are compiled from published studies and community-reported usage — individual response varies and lower end is always preferred.
Does Exemestane (Aromasin) suppress natural testosterone?
Exemestane (Aromasin) causes minimal suppression of the HPTA axis (score 0/10). PCT may still be advisable depending on stack and duration.
Is Exemestane (Aromasin) liver toxic?
Hepatotoxicity rating: Low. Non-17αα compound — liver stress is lower but still warrants periodic monitoring during a cycle.
What is Exemestane (Aromasin) typically used for?
Exemestane (Aromasin) is commonly used for: On-cycle estradiol management when bloodwork confirms elevation, Preferred over anastrozole when no-rebound profile matters, All experience levels. Intended-use context does not imply safety — every use case carries the same underlying pharmacological risks.
Citations
- Mauras N et al.. 2003. J Clin Endocrinol Metab — Pharmacokinetics and dose finding of exemestane (Aromasin) in young males ages 14-26 at 25mg PO daily x 10 days. Terminal t½ 8.9h — substantially shorter than the 27h figure derived from the postmenopausal-women clinical PK package on the FDA Aromasin label.
- FDA Aromasin label. 2018. FDA Drugs@FDA — Adjuvant breast-cancer dose for postmenopausal women: 25mg PO once daily. Reference for the 'clinical' tier of doseContext; on-cycle PED use is at 12.5mg EOD or 25mg E3D and is NOT FDA-labelled.
- Geisler J et al.. 1998. J Clin Endocrinol Metab — Exemestane is a steroidal suicide inhibitor of aromatase; covalent enzyme inactivation explains the absence of estrogen rebound on discontinuation.
- FDA Aromasin label (postmenopausal-women indication; reference for the historical 27h half-life and 25mg once-daily clinical dose). Available via accessdata.fda.gov.
Disclaimer
StackItSmart is an independent harm-reduction reference. The content above is compiled from peer-reviewed literature and is not medical advice, not an endorsement, and not a recommendation to use Exemestane (Aromasin). Performance-enhancing compounds carry legal, endocrine, cardiovascular, and hepatic risks. Consult a licensed clinician before any decision. StackItSmart does not provide sourcing, procurement, or dosing prescriptions.