Starting Dose of Oral Micronized Progesterone
For women with a uterus receiving estrogen-based hormone replacement therapy, start oral micronized progesterone at 200 mg daily for 12-14 days per month in a sequential regimen, or 100 mg daily for 25 days per month if continuous therapy is preferred. 1
Dosing Regimens Based on Clinical Goals
The choice between sequential and continuous dosing depends primarily on whether the patient desires withdrawal bleeding:
Sequential (Cyclic) Regimen - For Patients Accepting Withdrawal Bleeding
- 200 mg daily for 12-14 days per month 1
- This is the most commonly recommended starting dose in guidelines
- Provides proven endometrial protection for up to 5 years 2
- Induces predictable withdrawal bleeding
Continuous Regimen - For Patients Avoiding Withdrawal Bleeding
- 100 mg daily for 25 days per month 3, 4
- Achieves amenorrhea in 91-93% of women by 6 months 3
- Fully inhibits endometrial mitoses and provides adequate endometrial protection 4
- Better compliance due to absence of bleeding
Alternative Sequential Dosing
- 300 mg daily for 10 days per month 5, 6
- This higher dose for shorter duration is also effective
- Typically taken at bedtime to minimize transient drowsiness
- Achieves secretory transformation approaching physiological range 6
Dosing in Special Populations
Adolescents and Young Women with Premature Ovarian Insufficiency:
- Start with 200 mg daily for 12-14 days every 28 days (sequential) 7
- Alternative: 100-200 mg daily for cyclic administration 8
- Micronized progesterone is preferred over synthetic progestins due to lower cardiovascular and thrombotic risk 7
Route of Administration Considerations
Oral administration is the standard route, though the guidelines note:
- Vaginal micronized progesterone (off-label) may provide endometrial protection at 100 mg every other day or 4% gel (45 mg/day) for 10+ days/month 2
- Transdermal progesterone does NOT provide adequate endometrial protection 2
Critical Monitoring Points
The FDA label confirms that 100 mg daily or 200 mg for 10-12 days per month are the established doses for endometrial protection 9. Clinical trials demonstrated that 200 mg daily in sequential regimens reduced endometrial hyperplasia from 64% (estrogen alone) to only 6% (estrogen plus progesterone) over 36 months 9.
Common Pitfalls to Avoid
- Do not use doses below 100 mg daily - suboptimal endometrial protection 6
- Do not use transdermal progesterone for endometrial protection - it is ineffective 2
- Do not skip the progestogen in women with a uterus - unopposed estrogen carries 2.1-5.7 times increased risk of endometrial hyperplasia and cancer 5
- Take at bedtime if using 200-300 mg doses to minimize transient drowsiness 1, 5
Dose-Response Evidence
Studies demonstrate clear dose-dependent effects: 300 mg daily produces secretory changes approaching physiological range, while 100-200 mg provides adequate endometrial protection with full mitotic inhibition 6, 4. The lower continuous dose (100 mg for 25 days) works by prolonged exposure rather than higher peak levels 3, 4.