Estrogen Blockers
Overview
In most trans men, testosterone therapy alone sufficiently suppresses estrogen. However, some individuals have persistently elevated E2 despite adequate T levels. In these cases, an aromatase inhibitor may be used.
When Are Estrogen Blockers Needed?
- E2 > 50–100 pg/mL despite T in target range (300–1,000 ng/dL)
- Symptoms of high E2 (bloating, mood swings, breast tenderness)
- Menstruation persists despite adequate T levels
Available Options
| Medication | Dose | Notes |
|---|---|---|
| Anastrozole (Arimidex) | 0.5–1 mg/week | Most common |
| Letrozole (Femara) | 2.5 mg/week | Alternative |
| Exemestane (Aromasin) | 12.5–25 mg/week | Less common |
How They Work
Aromatase inhibitors block the aromatase enzyme, which converts testosterone into estradiol. By blocking this conversion, less T is turned into E2.
Side Effects
| Side Effect | Notes |
|---|---|
| Joint pain | Most common |
| Fatigue | Occasional |
| Headaches | Occasional |
| Bone density (long-term) | Theoretical risk; monitor if used long-term |