Micronized progesterone is a natural form of the hormone produced from soy or a wild Mexican yam that is identical to the progesterone produced by a woman's ovaries. It is prescribed to regulate menstrual cycles, to treat infertility, and as part of hormone replacement therapy during menopause when a woman's levels of estrogen and progesterone decrease. Progesterone and estrogen combinations are also present in birth control pills. Micronized progesterone can be ingested orally or thorough a cream or patch applied to the skin.
Researchers found that estrogen therapy used alone increases the risk of uterine cancer. Progesterone was added to estrogen supplements to reduce this risk, and micronized progesterone produced fewer side effects than synthetic forms of the hormone. Micronized progesterone might also protect against osteoporosis and raise the level of healthy cholesterol. The only known side effect from the drug is sleepiness, which can be addressed by taking the hormone at bedtime.
Women produce estrogen and progesterone during childbearing years, with the levels rising or falling with ovulation. The two hormones protect a fetus while it develops in the uterus, meaning the level of both substances is higher during pregnancy. When a woman stops ovulating during menopause, her body stops making estrogen and progesterone. The level of progesterone drops to zero once a woman has passed through menopause.
Hormone replacement therapy helps counteract symptoms of menopause that create discomfort in some women. It can be beneficial for hot flashes, to regulate mood swings, prevent excessive sweating at night, and for other physical maladies. Micronized progesterone, in combination with estrogen, provides relief while decreasing the risk of uterine cancer from estrogen use alone.
Before micronized progesterone was discovered, doctors routinely prescribed progestins, a synthetic form of the hormone produced in laboratories. Progestins often produced cramping, nausea, and dizziness. Some women also complained of headaches along with muscle and breast pain while using the synthetic hormone. Human studies showed that some of these side effects could be harmful.
A doctor can help a woman decide whether to use the oral or topical form of micronized progesterone. Creams, gels, or a patch applied to the skin allow absorption directly into the bloodstream, but there are no standards to regulate the amount of progesterone in each formula. The oral form passes through the liver and requires higher doses to obtain the same benefits. Common oral doses range from 200 mg to 400 mg per day.