Please watch the following Progesterone Video.  Or, if you prefer to read:

Not a day goes by that I don’t talk to one or more patients about the wonderful hormone called progesterone.  I often wish I could tell everyone the whole story at once.  So today I decided to do just that.

In medical school, we learned that progesterone is necessary for pregnancy. That’s why it’s called “progesterone”, because it promotes gestation, otherwise known as pregnancy.  In fact, it’s so important for pregnancy that progesterone deficiency is a major cause of recurrent miscarriage.  Not having enough progesterone to support the growing uterine lining causes that lining to be shed, along with the baby who is attached to it.

Outside of pregnancy, progesterone not only prepares the uterine lining for the possibility of pregnancy, but it also stabilizes that lining so it doesn’t grow out of control under stimulation by estradiol.

It is for this reason that every gynecologist and family doctor knows-or should know-that you have to give progesterone to women who take estrogen for hormone replacement in menopause.  If you fail to protect that lining while giving estrogen or an estrogen-like drug, the lining can eventually become cancerous.

This happened to one of my favorite patients many years ago.  Her previous doctor prescribed horse urine hormones, otherwise known as Premarin, without progesterone.  This went on for many years.  When she came to me asking for a refill, I told her this was a no-no.  An endometrial biopsy confirmed uterine cancer.  She underwent a hysterectomy and has been happily receiving bio-identical hormones ever since.

But what about women who have had a hysterectomy and therefore don’t have to worry about uterine cancer?  In medical school, we were taught that they don’t need progesterone.  If the uterus is the only organ in the body that responds to progesterone, this would make perfect sense.  However, nothing could be farther from the truth.  There are progesterone receptors everywhere in the body.

Consequently, women who lack progesterone have more:



mood swings


low libido

poor concentration

breast cancer


endometrial cancer



heart palpitations


Did you notice I mentioned breast cancer?  Just like the lining of the uterus, breast cells respond to estrogen by growing.  Again, progesterone stabilizes that growth so it doesn’t get out of control.  In fact, women with breast cancer who are treated with progesterone and testosterone actually do better than those who do not.  But that is another story.

The bottom line is that progesterone has numerous benefits, whether you have a uterus or not.  For example, it:

improves sleep

reduces anxiety and depression

reduces heart palpitations and dizziness

lowers blood pressure

facilitates elimination of fats

reduces breast tenderness

reduces inflammation

promotes new bone formation

raises the “good” HDL cholesterol

increases metabolism

enhances thyroid hormone activity

promotes immunity

promotes myelination of nerve cells

increases scalp hair

improves sex drive

and much more.

Normally, when a woman runs out of eggs, she enters menopause.  Everyone loves to say goodbye to those pesky periods, especially if they were painful, heavy, or marked by bad PMS.  But the lack of periods is perhaps the only good consequence of menopause.

The eggs are what cause formation of follicles in the ovaries.  The follicles produce three critical hormones:  estradiol, progesterone, and testosterone.  Without these hormones, a number of symptoms may occur that affect quality of life.  Just as important, a woman’s risk of all kinds of diseases goes way up.  Among others, such diseases include breast cancer, heart disease, stroke, osteoporosis, diabetes, and Alzheimer’s.  Needless to say, restoring these hormones can have a profoundly positive effect on a woman’s life, both immediately and in the long term.

But once in a while, a woman on hormone replacement will experience vaginal bleeding.

There are basically 4 causes of bleeding in the postmenopausal woman:

1.      Endometrial hyperplasia.  This is when the lining gets too thick due to a mismatch between estrogen stimulation and progesterone stabilization. More about this in a minute.
2.      Fibroids.  These are disorganized masses of uterine muscle that are stimulated by estrogen and tend to cause bleeding and sometimes pain when they contract.
3.      Polyps.  Like fibroids, these grow in the uterus and are harmless but can cause bleeding.
4.      Endometrial cancer.  As I explained before, this results from years of unopposed estrogen stimulation.  Knock on wood, I’ve never seen or even heard of a case of endometrial cancer in a woman receiving hormone pellets. But this is because we always prescribe progesterone with the pellets.

Returning to the first cause of uterine bleeding, this is the most common. It simply results from not having enough progesterone for the amount of estrogen.

There are 3 common reasons for this:

1.      The dose of progesterone may not be high enough.
2.      Progesterone is being taken transdermally by applying it as a cream. The transdermal route is not nearly as effective as the oral route, even though it’s the same hormone.
3.      The woman is buying her progesterone from a regular retail pharmacy. During processing, progesterone is “packaged” into really tiny packets so it can be absorbed readily through the GI tract.  This process is called “micronization”.  Unfortunately, drug company-supplied progesterone is commonly micronized to a size of 50 microns, whereas compounding pharmacies micronize them to 5 microns or smaller.  In case it’s not clear, that’s REALLY tiny.  As a result, compounded progesterone is far better absorbed into the body than retail progesterone, and is more effective.  Therefore, if a woman has bleeding while taking retail progesterone, she should definitely switch to compounded progesterone.  It’s only more expensive because your insurance may not cover it, but, as the adage goes, you get what you pay for.  Your health is worth the investment.

While I’m on the subject of formulations, I often receive requests from insurance companies to substitute Provera for progesterone, because Provera is cheaper.  Insurance pharmacists obviously skipped chemistry class because they seem to think there is some relationship between the two.  You might say it’s kind of like humans and robots:  Robots can be made to look and talk somewhat like humans, but you don’t want to develop an intimate relationship with one.  Nor do you want to put chemicals in your body for the rest of your life that try to masquerade as progesterone.  Both Provera and progesterone protect the lining of the uterus, but Provera does exactly the opposite of progesterone in many other respects, such as INcreasing breast cancer, heart attacks, blood clots, strokes, anxiety, mood swings, and depression.  Progesterone DEcreases all of these.

But there is more:  Did you know that drugstore progesterone contains peanut oil, titanium dioxide, D&C Yellow No. 10 and FD&C Red No. 40?  Let’s take a look at each these so-called “inactive” ingredients:

*       Titanium dioxide.  This is also found in many sunscreens and makeup, and has been found to cause nerve damage.  Also, the International Agency for Research on Cancer (IARC) considers titanium dioxide “possibly carcinogenic to humans.”
*       Peanut oil.  Of course this is made with peanuts, which are one of the 8 most common food allergens.  There is no reason to package progesterone in peanut oil.
*       Yellow and Red dyes.  Why do we need them?  Does progesterone work better if the capsule is painted pink?  Of course not.  But it does damage
the intestinal lining, as all dyes do, leading to immune dysfunction.  There is no need to dye a human hormone to make it pretty.  More importantly, it’s unhealthy to do so.

Bottom line?  If you want the best results, get your progesterone from a compounding pharmacy.

Lastly, if you are wondering why I usually recommend progesterone capsules instead of cream, it’s because hormones have different effects AND effectiveness depending on how they enter the body.  Oral progesterone is more effective for insomnia, breast protection, and uterine protection than cream.

So there you have it:  Progesterone in a nutshell.  Thanks for listening to “Progesterone 101.”  I hope you have learned something valuable about this wonderful hormone.  I’m Dr. Ray Andrew, also known as “that hormone doctor from Moab.”


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