Compare · Aromatase inhibitor
Exemestane vs Letrozole
Both are aromatase inhibitor compounds. Here's how they line up on the evidence — graded the same way.
| Exemestane | Letrozole | |
|---|---|---|
| Evidence | 10/10 | 10/10 |
| Class | Aromatase inhibitor | Aromatase inhibitor |
| Summary | Exemestane is an oral, steroidal third-generation aromatase inhibitor — an FDA-approved breast-cancer drug, not a peptide. Bodybuilders use it off-label to suppress estrogen, an unapproved and unstudied practice that is banned in sport (WADA S4) and can be genuinely harmful when estrogen is crashed. | Letrozole is an oral, nonsteroidal third-generation aromatase inhibitor — an FDA-approved breast-cancer and (off-label) fertility drug, not a peptide. Bodybuilders use it off-label to suppress estrogen, an unapproved and unstudied practice that is banned in sport (WADA S4) and can be genuinely harmful when estrogen is crashed. |
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Exemestane
Exemestane, sold as Aromasin, is a pill you swallow that lowers the body's estrogen. It is a steroidal third-generation aromatase inhibitor (AI) — a real, well-studied cancer drug. It is worth being clear about what it is and isn't: exemestane is not a peptide, not a SERM (selective estrogen…
Letrozole
Letrozole, sold as Femara, is a pill that lowers the amount of estrogen in your body. It belongs to a class of drugs called aromatase inhibitors (AIs — they block the enzyme that builds estrogen). It is a real, well-studied medicine with strong research behind it, used in cancer care and in…