Letrozole Research Guide

Full name: Letrozole (Femara)

A third-generation aromatase inhibitor used off-label as first-line ovulation induction in PCOS. Superior to clomiphene for female fertility due to less anti-estrogenic effect on endometrium. Also used in men to control estradiol on TRT.

How Letrozole Works

Reversibly inhibits aromatase (CYP19A1), blocking conversion of androgens to estrogens. In women, transient estrogen reduction triggers hypothalamic GnRH release for FSH surge. In men, reduces estradiol while maintaining testosterone.

Dosing Protocol

• Typical dose: 2.5-7.5 mg (women, day 3-7); 0.5-2.5 mg (men, 2-3x/week)
• Frequency: Cyclic (women) or 2-3x weekly (men)
• Duration: Per cycle (women); ongoing (men)
• Route: Oral tablet

Reported Benefits

• Ovulation induction (PCOS)
• Higher live birth rates than clomiphene
• No anti-estrogenic endometrial thinning
• Estradiol control in men
• Lower multiple pregnancy rate

Potential Side Effects

• Hot flashes
• Joint pain
• Headache
• Fatigue
• Bone density concern (long-term)
• Mood changes

Research Citations

1. NEJM: Letrozole vs clomiphene for PCOS (2014) - Letrozole produced significantly higher ovulation (61.7% vs 48.3%), pregnancy (27.5% vs 19.1%), and live birth rates (18.7% vs 9.4%) in PCOS women.
2. Letrozole for male estradiol management (2020) - 1.25mg 3x/week reduced estradiol from 52 to 24 pg/mL while maintaining testosterone levels in hypogonadal men on TRT.

Related Fertility Compounds

• HMG - Full Profile
• HCG (Fertility) - Full Profile

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