Micronized Progesterone
Bioidentical progesterone in a micronized oral or vaginal form. Used for endometrial protection in HRT, luteal support in fertility care, and increasingly in transfeminine regimens where some seek its putative breast and mood effects.
01 Overview
Micronized progesterone is chemically identical to the human hormone. Micronization improves absorption of an otherwise poorly bioavailable molecule. It is standard for opposing estrogen's effect on the endometrium in menopausal HRT and is used vaginally for luteal phase support in assisted reproduction.
In transfeminine care its role is debated: proponents cite anecdotal breast and libido benefits, while controlled evidence for added feminization is limited. Oral progesterone produces sedating neurosteroid metabolites (allopregnanolone), which is why it is often taken at night.
02 Mechanism
Bioidentical progesterone agonises progesterone receptors, transforming estrogen-primed endometrium to secretory tissue; hepatic metabolism yields allopregnanolone, a GABA-A modulator causing sedation.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Endometrial protection | 100–200 mg/day | Oral | 100 mg continuous or 200 mg cyclic at bedtime. |
| Alternative route | 100–200 mg/day | Rectal | Used off-label to raise serum levels vs oral. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Endometrial protectionOpposes estrogen-driven endometrial proliferation. | Clinical | ||
| Sedation / sleep aidAllopregnanolone metabolite promotes sleep when taken orally at night. | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Drowsiness and dizzinessSedation from allopregnanolone, especially with oral dosing. | Mild | Common (oral) | Clinical | |
| Mood changes / low moodSome report depressed mood or irritability. | Mild | Uncommon | Observational |