Clinical comparison · Menopause & vasomotor symptoms · Updated 2026-07-02
Micronized progesterone and medroxyprogesterone acetate are the two progestogens most often paired with estrogen for endometrial protection. This table reproduces labeled facts and published cohort findings verbatim, cell by cell. It does not declare a preferred agent — progestogen choice is made with your prescriber.
Every value below is reproduced verbatim from an FDA prescribing-information document or a published clinical trial, and each cell links to its source. This page does not rank the two options, does not declare one safer or more effective, and is not medical advice.
| Dimension | Micronized progesterone | Medroxyprogesterone acetate (MPA) |
|---|---|---|
| Progestogen type | Bioidentical progesterone, identical to endogenous hormone[1] | Synthetic progestin (17-hydroxyprogesterone derivative)[2] |
| Primary HRT role | Endometrial protection alongside estrogen[1] | Endometrial protection alongside estrogen[2] |
| Breast-cancer signal (E3N cohort) | No significant increase in breast-cancer risk observed with micronized progesterone[3] | Increased breast-cancer risk observed with synthetic progestins[3] |
| Notable labeled adverse effect | Somnolence/dizziness reported (dosed at bedtime); contains peanut oil[1] | Discussed within combined HRT risk profile[2] |
| Typical HRT dosing | 100 mg nightly (continuous) or 200 mg for 12-14 days/month (cyclic)[1] | Dosed within combined estrogen-progestin regimens[2] |
What the E3N cohort measured
A large French prospective cohort that examined hormone therapy and breast-cancer incidence by progestogen type. It reported no significant increase in breast-cancer risk among micronized-progesterone users, in contrast to an increased risk observed with synthetic progestins over the follow-up period. Cohort associations are not causal proof. E3N cohort (Breast Cancer Res Treat 2008)
Where the labeled facts come from
Progestogen type and micronized-progesterone dosing/side effects are taken from the FDA Prometrium label; MPA facts are attributed to the NAMS 2022 position statement, which discusses both agents. NAMS 2022 Hormone Therapy Position Statement
Micronized progesterone is bioidentical (identical to the hormone the body makes), while medroxyprogesterone acetate is a synthetic progestin. Both are used for endometrial protection with estrogen (FDA Prometrium label; NAMS 2022).
It reported no significant increase in breast-cancer risk among micronized-progesterone users, versus an increased risk observed with synthetic progestins during follow-up. This is an observational association, not individual medical advice.
The FDA Prometrium label notes somnolence and dizziness, so it is commonly dosed at night. It also contains peanut oil and is contraindicated in peanut allergy.
Editorial reviews from ClearHormones of telehealth providers in this category. These are not treatment recommendations, and prescribing decisions rest with a licensed clinician.