Aromasin (Exemestane): Complete Reference for Bodybuilding

Aromasin, or Aromasin exemestane as it is often searched, is the brand name for exemestane, a steroidal aromatase inhibitor made by Pfizer and available as generic exemestane from a dozen manufacturers. Its approved use is adjuvant treatment of hormone receptor-positive breast cancer in postmenopausal women, where it cuts estrogen production by 85–95% at the standard 25 mg daily dose. Its widespread off-label use, and the subject of this site, is estrogen control in men on testosterone: on a cycle, during post-cycle therapy, and occasionally on TRT.

What makes Aromasin different from the other two aromatase inhibitors is its class. Exemestane is a Type I, steroidal inhibitor. It is shaped like androstenedione, the enzyme's natural substrate, so aromatase processes it and is permanently inactivated in the process. Anastrozole and letrozole are Type II, non-steroidal inhibitors that block the enzyme reversibly and let it go as the drug clears. That single structural fact drives every practical difference: every-other-day dosing, gradual recovery after stopping, a low rebound risk, and compatibility with a SERM in PCT.

This page is the reference for the drug on this site. It answers what is Aromasin in full: its generic names, how it works, the on-cycle protocol, dosing by context, blood work, PCT, side effects, the comparison with Arimidex and where to get it, with a link to the full article on each.

The Aromasin generic name is exemestane. The chemical name is 6-methylideneandrosta-1,4-diene-3,17-dione, and the molecule is a synthetic derivative of androstenedione, which is why it is classed as steroidal. Pfizer's brand is Aromasin; the generics are sold as exemestane by Roxane, Alvogen, Greenstone and others in the US, and under regional brands such as Xtane in India, Exemestan in Europe and Aromasil in Latin America. All contain the same 25 mg of exemestane per tablet, and the generic is priced at a fraction of the brand. The brand-versus-generic question from the patient side — manufacturers, equivalence and price — is covered in exemestane brand name.

The Aromasin half-life guide covers the pharmacokinetics, including why the 24-hour half-life and the multi-day effect diverge and where the forum figure of 9 hours came from.

Aromatase converts testosterone and androstenedione into estradiol and estrone, mostly in body fat. Exemestane enters the enzyme's active site as a false substrate; the enzyme begins processing it and is destroyed, a mechanism called suicide inhibition. Estrogen production at that site only resumes once the body has synthesised new aromatase, which takes days.

Three consequences follow. The dosing interval is every other day, because daily dosing destroys enzyme faster than it is rebuilt and crashes estradiol within two to three weeks. Recovery after stopping is gradual, three to seven days, which makes an overshoot easier to catch than with anastrozole and eliminates the estrogen rebound a reversible inhibitor can produce. And because the steroidal mechanism does not touch the gonadotropin response to GnRH, exemestane can run alongside a SERM in PCT where anastrozole cannot.

The steroidal structure also gives exemestane a weak androgenic metabolite, 17-hydroexemestane, negligible at cycle doses but the leading explanation for why joints tolerate it better than anastrozole. The aromatase inhibitors complete guide sets exemestane against the other two drugs in the class.

The starting point on cycle is 12.5 mg every other day, half a scored 25 mg tablet, for 400–600 mg of testosterone per week. That dose puts the largest share of men in range without immediate over-suppression risk. Two variables decide whether it holds: body fat, because aromatase lives in adipose tissue and a man at 20% converts far more than a man at 12%, and genetics, since enzyme expression varies between men independently of composition.

Timing against injections is a refinement, not a requirement. Dosing 24–48 hours after each shot places the blockade at the testosterone peak; on a Monday and Thursday pin schedule that means Tuesday and Friday plus a Sunday dose to hold the EOD rhythm. Many men dose on a fixed EOD schedule without tracking pin days and hold estradiol steady. The Aromasin bodybuilding guide covers the on-cycle protocol from week one to PCT, and the 500 mg test cycle protocol works through the most common cycle week by week.

The Aromasin dosage guide expands each row: the 12.5 versus 25 mg decision, tablet splitting and storage, timing on different injection schedules, and why TRT dosing is a fraction of cycle dosing.

Blood work at week four or five is the calibration step. By then testosterone and estradiol from a consistent injection schedule have reached steady state and exemestane has settled into its suppression. Order an LC/MS or "sensitive" estradiol; the standard ECLIA test cross-reacts with other steroids in men on testosterone and reads high.

Draw a lipid panel and liver enzymes in the same sample. The how to lower estrogen in men guide sets out the male reference ranges and what the assay choice does to the number.

Post-cycle therapy works through a SERM, tamoxifen or clomiphene, blocking estrogen receptors at the pituitary and hypothalamus so that LH and FSH rise and the testes restart. Anastrozole has been shown to suppress that gonadotropin response to GnRH; exemestane has not. That makes Aromasin the only pharmaceutical AI that can run alongside a SERM without dulling recovery, and an AI is needed in early PCT because estradiol stays high relative to clearing testosterone and suppresses the restart.

Standard protocol: exemestane 12.5 mg EOD through weeks one to three of the SERM phase, tapering to every third day and stopping by week four, with Nolvadex 40/40/20/20 or Clomid 50/50/25/25 continuing for the full four to six weeks. Men who ran anastrozole on cycle switch to exemestane here after a two-to-three-day gap. The Aromasin vs Arimidex comparison covers why PCT is the one place the choice between the two is not close.

At cycle doses, Aromasin side effects are almost entirely the result of estradiol suppressed too far rather than drug toxicity: dry joints, libido loss despite high testosterone, low mood, fatigue, flat pumps and brain fog, all of which resolve as estradiol recovers. Compound-specific effects are minor by comparison: hot flashes and headache in the first week, and a small rise in liver enzymes when stacked with an oral steroid.

Over years of use, every aromatase inhibitor lowers bone density and HDL. The MA.27 trial, 7,576 women on exemestane or anastrozole for five years, found less osteoporosis, less hypercholesterolemia and less hypertriglyceridemia on exemestane, and community reports consistently put less joint pain on it at the same estradiol. The aromatase inhibitors side effects guide covers each effect, the trial numbers and how to tell a crash from a compound problem; the site's side effects page covers the clinical profile.

For most men on cycle the answer is Aromasin, for three reasons: PCT compatibility, so no compound switch at cycle end; less joint pain at comparable estradiol; and a gradual offset that turns an overshoot into a warning rather than a crash. Arimidex wins where fine titration matters, at 200–300 mg of testosterone per week or on TRT, since 0.25 mg steps are possible and estradiol responds to a change within a day or two. The full comparison includes the MA.27 data, the Reddit consensus and the switching protocol.

Pharmaceutical exemestane, brand or generic, is assayed to within a few percent of label and is what every protocol was built on. It needs a prescription, most often obtained through a TRT clinic that manages estradiol, and with a GoodRx or SingleCare card generic exemestane costs $17–38 for 30 tablets at US retail chains, under $1 a tablet by mail order. Research chemical exemestane is the same molecule made outside regulation and is only as reliable as the vendor's independent testing. Underground lab product carries no testing at all. The Aromasin for sale guide covers current prices, legal routes and how to judge a source; the products page lists the forms it comes in.

Aromasin.org is an independent educational resource. We are not affiliated with Pfizer, any pharmaceutical manufacturer, or healthcare provider. This content is for informational purposes only and does not constitute medical advice.