Regestrone (norethisterone) is a synthetic progestogen, or a progestin. Progestogen is a naturally-occurring hormone which, along with estrogen, is largely responsible for reproductive characteristics in women, influencing pregnancy, estrous, and menstrual cycles. A progestin is a synthetic version of progestogen that fills the same role.

Progestins or progestogens are always present in combined hormonal birth control, along with some form of estrogen. Regestrone is a progestin-only medication, however; it is not mixed with estrogen or any other medication. Progestin-only medications have a range of uses:

• Birth Control - Also known as a minipill, Regestrone can be used for birth control, though it's not as effective as combined hormonal contraceptives. Use is typically reserved for those unable to take combined hormonal products for some reason.
• Delaying Periods - A popular use for this product, Regestrone at sufficient doses will delay a period from starting. Women often use this during weddings, honeymoons, vacations, and so forth. Menstruation will resume 1 to 3 days after Regestrone use stops.
• Breast Cancer - This product can help prevent certain types of breast cancer from growing or spreading. It is usually administered with other medications.
• Uterine Hemorrhage - as a treatment for non-menstrual vaginal bleeding or a precaution before surgery or certain medical procedures, Regestrone will stop uterine bleeding or reduce the likelihood of it starting.
• Heavy Periods - Taken prior to a period, flow should be lighter and PMS symptoms, if experienced, should be minimized.
• Developing Female Characteristics - The effects of Regestrone in this area are subtle, but it does make a difference in making breasts and buttocks rounder, reducing dry skin and brittle nails, and so forth. It is sometimes taken by men who wish to develop female characteristics, though results vary widely and on its own it will do little; it is best taken along with estrogen.

Equally important is who should not take Regestrone. Women with certain health conditions are at higher risk of experiencing severe side effects while taking this product and should seek an alternative treatment:

• Hyperlipidemia (high blood fat)
• History of blood clots
• History of heart problems or angina
• Impaired liver function
• Pregnant or trying to become pregnant
• Breastfeeding

Men, young women who haven't had their first period, and post-menopausal women should not take Regestrone without explicit doctor instruction.

Taking Regestrone

Regestrone comes in tablets of 5 mg strength; it is not available in other dosage amounts, so treatment often involves taking multiple tablets. Tablets can be taken without regard to food, though a full glass of fluid is recommended with each dose.

Dosage varies quite a bit according to what's being treated. Standard treatment guidelines for common uses are:

• For birth control take 1 tablet per day, at the same time each day.
• To delay a period start taking 3 tablets per day three days before the period is due. Continue taking 3 tablets per day for as long as prevention is desired. The period will commence one to three days after treatment ends.
• To treat breast cancer 8 to 12 tablets are typically taken per day. Duration of use is variable; a doctor will advise.
• To prevent or stop uterine hemorrhage take 1 tablet three times per day for up to ten days.
• To prevent PMS symptoms or prevent heavy period flow take a tablet two or three times per day during the week preceding a period.
• To develop female characteristics a doctor should be consulted or in-depth research performed by the patient. In both men and women dosage and duration of treatment is highly variable depending on intent, causes, and patient response.

Something to keep in mind during treatment with Regestrone is that it doesn't stay in the body very long. It is critical that tablets be taken at the same time each day to maximize effects; a delay as little as 3 hours can nullify effects.

St. John's wort should be strictly avoided while taking Regestrone; potentially fatal interactions are possible. Though generally less dangerous, other medications may also interact with Regestrone, making it less effective. Always double-check with a doctor or pharmacist before mixing medications.