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Dr. Jerilynn C. Prior, Scientific Director, Centre for Menstrual Cycle and Ovulation Research

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Cyclic Progesterone Therapy

by Dr. Jerilynn C. Prior, Scientific Director, Centre for Menstrual Cycle and Ovulation Research

Why Might I Need To Take Cyclic Progesterone Therapy?

Progesterone is one of two important hormones for women (estrogen is the one we usually hear about). Menstrual cycle hormone levels can be disturbed, even during regular cycles. The most common disturbance is of ovulation causing progesterone levels to become too low or absent.

Your doctor may prescribe progesterone to control heavy periods, severe menstrual cramps (dysmenorrhea) or to help with irregular periods, acne, unwanted hair, low bone density, or sore and lumpy breasts. Cyclic natural progesterone therapy may also help achieve fertility—but don't use medroxyprogesterone. It is also very important therapy in perimenopause for night sweats, breast tenderness or heavy flow.

What Medications Can I Choose?

Medroxyprogesterone (previously called Provera®) is a progestin, a chemical form of progesterone and has been used for over 40 years—it is a very close cousin of natural progesterone. It is stronger so the natural dose is 10 mg. a day. A one-day dose costs from 40 to 65 cents.

Oral micronized progesterone (Prometrium®) is the same thing your ovaries make. Three 100-mg. capsules is the natural dose. Because it causes sleepiness, take this medication on your way to bed. One day's dosage costs $2.50-3.00. It is less expensive if compounded in olive oil. Either medication will have important, positive effects on flow, breasts and bones.

When Do I Take It?

If you get a period regularly and your periods are usually 27-30 days apart, start progesterone on the 14 th day after flow began and take it for 14 days, or until cycle day 27. If your cycles are regular but short (for example, if your period lasts 19 – 26 days), then start progesterone on cycle day 12. You would take it for 14 days, that is, through cycle day 25.

If your period starts before you have finished the 14 days of progesterone (for example, on the 9th day of taking it) finish the full 14 days , but start the next progesterone 14 days after the period began (see Diagram 2 ) . This allows progesterone to “catch up” with the estrogen your body is making.

If your period starts while you are still taking progesterone, always continue taking it for the full 14 days. If this early flow persists, you may need a higher dose of progesterone, or to take it more than 14 days. The early flow is a sign of high estrogen over-stimulating the endometrium (lining of the womb).

If you have migraines, you need to take progesterone daily.

If you stop progesterone and don't start to flow after two weeks off, start taking progesterone again for 14 days. After this 14-day time on, take 14 days off progesterone.

As soon as your period returns, start taking progesterone again 14 days after the start of your flow, as shown in Diagram 1.

Are There Any Side Effects?

There are no serious side effects from progesterone therapy. It does not cause blood clots, migraine headaches or increase the risk for breast cancer. It effectively prevents endometrial cancer. Pharmacy references often state that progesterone causes everything that's been shown on the birth control pill (high dose estrogen and male-hormone-like progestins). In very rare instances, an allergy may occur. (Oral micronized progesterone is in peanut oil; therefore those with an allergy to peanuts must NOT take it.)

You may notice some changes in your breasts, feelings of warmth and other evidence of normal progesterone action. If you get moody, feel bloated and have very sore breasts, it means progesterone is temporarily stimulating your body to make high estrogen levels. This improves after one cycle.

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