Progesterone 100 vs 200mg for HRT
For endometrial protection in postmenopausal women on hormone replacement therapy, both 100 mg daily (continuous) and 200 mg for 10-14 days per month (sequential) of oral micronized progesterone are equally effective and guideline-endorsed options.
Dosing Regimens Based on Administration Schedule
The choice between 100 mg and 200 mg depends entirely on whether you're using a continuous or sequential regimen:
Continuous Combined Therapy
- 100 mg daily taken every day alongside continuous estrogen 1
- This provides consistent endometrial protection with the goal of amenorrhea
- FDA-approved dosing: 200 mg daily for 12 days per 28-day cycle 2
Sequential/Cyclic Therapy
- 200 mg daily for 10-14 days per month 1
- Typically days 10-24 or last 12-14 days of each cycle
- Results in predictable withdrawal bleeding
- Research confirms 200 mg sequential dosing provides robust endometrial protection 3, 4, 5
Evidence Quality and Strength
The AACE guidelines (2011) provide Level 1 evidence (RCT-based) supporting both dosing strategies 1. The FDA label confirms 200 mg daily for 12 sequential days as the approved regimen for endometrial protection 2.
Key research findings:
- 100 mg daily continuous provides adequate endometrial protection for up to 5 years 3
- 200 mg sequential for 10-14 days produces secretory transformation and prevents hyperplasia 4, 5
- Lower doses (100 mg sequential) show less consistent endometrial protection with more proliferative patterns 5, 6
Clinical Decision Algorithm
Choose 100 mg daily if:
- Patient desires amenorrhea (no monthly bleeding)
- Using continuous combined estrogen-progestin therapy
- Patient has poor tolerance for withdrawal bleeding
Choose 200 mg for 10-14 days/month if:
- Using sequential/cyclic estrogen therapy
- Patient prefers predictable monthly bleeding
- Following FDA-approved labeling exactly 2
- Concerned about minimizing total monthly progesterone exposure
Important Caveats
Do not use 100 mg sequential dosing - this provides inadequate endometrial protection 5, 6. Studies show 100 mg given only 10 days per month results in more proliferative endometrium and breakthrough bleeding compared to 200 mg 5.
Side effect profile: Both doses are generally well-tolerated. The 200 mg dose may cause more drowsiness/dizziness, which is why bedtime dosing is recommended 2. Some women experience premenstrual-type symptoms (mood changes, bloating) that may improve by switching between continuous and sequential regimens 1.
Monitoring: Any unexpected vaginal bleeding requires endometrial evaluation regardless of regimen 1. The guidelines emphasize low threshold for endometrial sampling as bleeding patterns don't reliably predict pathology 1.
Breast Safety Consideration
Emerging evidence suggests micronized progesterone may have a more favorable breast cancer risk profile compared to synthetic progestins 7, 3, though continuous daily exposure to any progestogen raises theoretical concerns about breast tissue 1, 8. This is another reason some clinicians prefer the sequential 200 mg approach, limiting monthly progesterone exposure while maintaining full endometrial protection.