In this article
If you have a uterus and your clinician prescribes estrogen for menopause symptoms, you will almost certainly hear about progesterone too. One of the most common forms is oral micronized progesterone, a capsule usually taken at bedtime. This guide explains what it is, why it is paired with estrogen, what the dosing on the FDA label looks like, and how it compares with the synthetic progestins used in older studies.
What oral micronized progesterone is
Progesterone is a hormone your ovaries made in the second half of each menstrual cycle. The prescription capsule contains progesterone that is made from a plant source and is chemically identical to the progesterone of human ovarian origin [1].
"Micronized" means the progesterone is ground into very fine particles. The FDA label for Prometrium, the brand-name capsule, explains that micronization increases how much progesterone your body absorbs when you swallow it [1]. The approved capsules come in 100 mg and 200 mg strengths [1].
You may also hear the word progestogen. It is the umbrella term for progesterone and the synthetic progestins, such as medroxyprogesterone acetate and norethindrone acetate [2]. Micronized progesterone is the one that matches your body's own hormone structurally [2].
Why women with a uterus need a progestogen
Estrogen makes the lining of the uterus, called the endometrium, grow. When estrogen is taken without a progestogen for a long time, that lining can overgrow. This is called endometrial hyperplasia, and it raises the risk of endometrial cancer [2]. The Menopause Society says the menopause-related reason to use a progestogen is to prevent that overgrowth, and that women with a uterus using systemic estrogen should take an adequate progestogen [2].
When the progestogen dose is adequate, the risk of endometrial cancer is not higher than in women who are not taking hormones [2]. If you have had a hysterectomy, you generally do not need a progestogen for this purpose. Our guide to HRT after hysterectomy explains why.
What the PEPI trial showed
Much of what we know about micronized progesterone and the uterus comes from the Postmenopausal Estrogen/Progestin Interventions (PEPI) trial. It was a three-year randomized, double-blind, placebo-controlled trial of 875 healthy postmenopausal women aged 45 to 64 [4]. Women were assigned to placebo, estrogen alone, or estrogen plus one of three progestogen regimens, one of which was micronized progesterone 200 mg a day for 12 days a month [4].
In the endometrial results, which covered 596 women, those taking estrogen alone were much more likely than those on placebo to develop hyperplasia. For example, atypical hyperplasia occurred in 11.8% of the estrogen-alone group and none of the placebo group [3]. The three estrogen-plus-progestogen groups, including the micronized progesterone group, had hyperplasia rates similar to placebo [3]. The researchers concluded that cyclic micronized progesterone protected the endometrium from the changes seen with estrogen alone [3].
- Hyperplasia ~64%
- No hyperplasia ~36%
- Hyperplasia ~6%
- No hyperplasia ~94%
- Hyperplasia ~3%
- No hyperplasia ~97%
In a 3-year randomized trial of 358 women with a uterus, hyperplasia occurred in 64% on estrogen alone, 6% on estrogen plus cyclic micronized progesterone, and 3% on placebo [1].
PEPI also looked at heart-related blood tests. Estrogen with cyclic micronized progesterone raised HDL ("good") cholesterol more than the estrogen-plus-progestin regimens did [4]. That is a lab marker, not proof of fewer heart attacks, but it is one reason researchers took an interest in micronized progesterone.
How it is taken: label dosing
For preventing endometrial hyperplasia, the Prometrium label gives one regimen: 200 mg by mouth as a single dose at bedtime, for 12 days in a row of each 28-day cycle, in a woman with a uterus who is taking daily conjugated estrogen tablets [1]. MedlinePlus describes the same 12-days-a-month schedule, taken in the evening or at bedtime [5].
The Menopause Society gives the same example of adequate dosing, 200 mg a day for 12 to 14 days a month, and notes that regimens can be sequential (part of the month) or continuous (every day) [2]. Many women choose a regimen that avoids monthly bleeding, and The Menopause Society says patient preference can and should be considered [2]. Your clinician decides which schedule and dose fit you, and some prescribe daily nightly dosing rather than the label's cyclic one.
| What the sources say | |
|---|---|
| Approved strengths | 100 mg and 200 mg capsules [1] |
| Label dose with estrogen | 200 mg at bedtime for 12 days of each 28-day cycle [1] |
| When to take it | At bedtime, because it can cause dizziness and drowsiness [1] |
| Trouble swallowing | Take with a glass of water while standing [1] |
| Missed dose | Take it when you remember unless the next dose is near; do not double up [5] |
| Peanut allergy | Do not use the approved capsules; they contain peanut oil [1] |
Why bedtime?
The label warns that the capsules may cause temporary dizziness and drowsiness, so take care with driving or using machinery, and it directs a single daily dose at bedtime [1]. The Menopause Society notes that oral micronized progesterone has mildly sedating effects and should be taken at night [2]. A review it cites found it shortened the time to fall asleep in postmenopausal women, though it did not lengthen total sleep [2].
The peanut oil warning
This is the one safety point specific to the capsule's ingredients. The approved capsules list peanut oil as an inactive ingredient, and the label says they must not be used by anyone allergic to peanuts [1]. If you have a peanut allergy, tell your clinician before you start, so they can choose a different option.
Other reasons the label lists for not taking it include unexplained vaginal bleeding, current or past breast cancer, active or past blood clots, a past stroke or heart attack, and liver disease [1]. For the full list of common and serious reactions, see progesterone side effects.
Micronized progesterone vs synthetic progestins
The Women's Health Initiative, the large trial behind most HRT headlines, tested a synthetic progestin, medroxyprogesterone acetate, not micronized progesterone [2]. The Menopause Society is clear that it is not known whether micronized progesterone carries the same risks of breast cancer, stroke, or blood clots, because trials have not been designed to test that [2]. Here is what the evidence suggests so far:
- Blood clots: micronized progesterone may be less likely to promote clots than other progestins [2].
- Breast cancer: some, but not all, observational studies suggest micronized progesterone may have a smaller association with breast cancer than synthetic progestins. Randomized trials are needed to confirm this [2].
- The uterus: with long-term use, observational studies suggest a possible higher risk of endometrial cancer with micronized progesterone than with other progestogens, and with cyclic rather than continuous regimens [2]. That is one reason adequate dosing and reporting any unexpected bleeding matter.
The Menopause Society says unscheduled bleeding that starts more than 6 months after beginning combined hormone therapy should be checked by a clinician [2].
Progesterone through WarriorBabe Health
WarriorBabe Health offers an oral progesterone capsule, taken nightly at bedtime, usually alongside an estrogen such as the estradiol patch or oral estradiol. Like the approved capsules, ours contains peanut oil, so it is not for anyone with a peanut allergy. You can browse all options on our hormone treatments page.
Our capsule is compounded by a licensed pharmacy. Compounded drugs are not FDA-approved, and the FDA does not review their safety, effectiveness, or quality before they are marketed [6]. FDA-approved oral micronized progesterone, like the product whose label is cited here, also exists. Your clinician can talk through both. To see whether hormone therapy might suit you, take the 2-minute quiz. For progesterone taken on its own, see can you take progesterone without estrogen?
Frequently asked questions
What is oral micronized progesterone used for in menopause?
Its FDA-approved use in menopause is preventing endometrial hyperplasia, an overgrowth of the uterine lining, in women with a uterus who take estrogen; the label names conjugated estrogen tablets [1]. The Menopause Society says women with a uterus using systemic estrogen should take an adequate progestogen [2].
What is the usual dose of micronized progesterone with estrogen?
The FDA label lists 200 mg at bedtime for 12 days in a row of each 28-day cycle, with daily estrogen [1]. The Menopause Society gives 200 mg a day for 12 to 14 days a month as an example of adequate dosing [2]. Your clinician may use a different schedule, such as nightly dosing, based on your needs.
Why should I take progesterone at night?
The capsules can cause dizziness and drowsiness, so the label directs a single dose at bedtime and advises caution with driving [1]. The Menopause Society notes its mildly sedating effect and recommends taking it at night [2].
Can I take micronized progesterone if I have a peanut allergy?
Not the approved capsules. They contain peanut oil and are contraindicated in people allergic to peanuts [1]. Tell your clinician about any peanut allergy so they can choose another option.
Is micronized progesterone safer than synthetic progestins?
It may be in some ways, but the evidence is not settled. Observational data suggest it may be less likely to promote blood clots and may have a smaller link to breast cancer than synthetic progestins, but randomized trials have not tested this [2]. It does protect the uterine lining when adequately dosed [3].
References
- Prometrium (progesterone, USP) capsules prescribing information. DailyMed, US National Library of Medicine. dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1cf237ff-c4f8-4faa-a7aa-77599c856889
- The 2022 hormone therapy position statement of The North American Menopause Society. Menopause. 2022;29(7):767-794. menopause.org/wp-content/uploads/professional/nams-2022-hormone-therapy-position-statement.pdf
- The Writing Group for the PEPI Trial. Effects of hormone replacement therapy on endometrial histology in postmenopausal women: the Postmenopausal Estrogen/Progestin Interventions (PEPI) Trial. JAMA. 1996;275(5):370-375. pubmed.ncbi.nlm.nih.gov/8569016/
- The Writing Group for the PEPI Trial. Effects of estrogen or estrogen/progestin regimens on heart disease risk factors in postmenopausal women: the Postmenopausal Estrogen/Progestin Interventions (PEPI) Trial. JAMA. 1995;273(3):199-208. pubmed.ncbi.nlm.nih.gov/7807658/
- Progesterone. MedlinePlus Drug Information. US National Library of Medicine. Revised 04/2026. medlineplus.gov/druginfo/meds/a604017.html
- US Food and Drug Administration. Understanding the risks of compounded drugs. www.fda.gov/drugs/human-drug-compounding/understanding-risks-compounded-drugs
This article is for general information. It is not medical advice and does not replace a visit with a licensed clinician who knows your history. Do not start, stop or change a medication without talking to your clinician. If you think you are having a medical emergency, call 911.
