Evidence comparison
Aromasin vs Arimidex: Aromatase Inhibitor Differences
A medically reviewed comparison of exemestane and anastrozole, including reversibility, monitoring, and why routine estrogen suppression is not recommended.
Medically Reviewed
Board-Certified OB-GYN, Hormone & Longevity Specialist — University of Texas
Reviewed 2026-08-21
Quick answer
Aromasin is the brand name for exemestane, an irreversible aromatase inhibitor, while Arimidex is the brand name for anastrozole, a reversible aromatase inhibitor. Neither should be used simply to normalize a lab number; treatment decisions should consider symptoms, a sensitive assay, and clinician evaluation.
Key takeaways
- Exemestane is irreversible; anastrozole is reversible.
- Do not treat a number without symptoms and clinical context.
- Over-suppression can be harmful.
Reversible versus irreversible inhibition
Exemestane irreversibly inactivates aromatase, while anastrozole reversibly inhibits the enzyme. The pharmacology affects how clinicians think about titration and recovery, but it does not make either drug appropriate for unsupervised use.
Why low estradiol matters
Estradiol is important in men for bone, sexual, and cardiometabolic health. Unnecessary suppression can cause joint symptoms, mood changes, and sexual dysfunction. Use a sensitive male estradiol assay when testing is clinically appropriate.
When to seek care
New breast tenderness, persistent sexual symptoms, severe mood change, or unexplained bone or joint symptoms warrant clinical evaluation rather than self-directed dose escalation.
Related HormoneStacks resources
Frequently asked questions
Should every man on TRT take an aromatase inhibitor?
No. Routine aromatase-inhibitor use is not appropriate for every person on TRT. A clinician should evaluate symptoms, testing quality, dose, adherence, and other causes first.
Sources and limitations
This educational page is not medical advice and does not replace an examination or individualized treatment plan. Review the underlying evidence and discuss decisions with a qualified clinician.