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Don’t Let Your Doctor Give You Horse Urine for Menopause!

by John Morgenthaler, Jonathan V. Wright, M.D.

No auto mechanic in his right mind would replace worn parts in a Mercedes with new parts made for a Chevy. Unfortunately, many physicians (and pharmaceutical companies) seem to have less common sense than the average auto mechanic when it comes to treating menopausal women.

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The "estrogen" replacement most doctors prescribe today for menopausal and premenopausal women is a pill known generically as conjugated equine estrogens (CEE). The best known brand of CEE is Premarin®. Many studies suggest that in many women, Premarin does help reduce symptoms of menopause, including hot flashes, vaginal thinning, memory loss, and urinary incontinence. It also appears to reduce the risk of developing postmenopausal cardiovascular disease (the leading killer of women) and osteoporosis (the crippling progressive bone weakness).

It also may help to prevent a significant proportion of Alzheimer's disease and senile dementia.

Premarin is Horse Estrogen Derived From Horse Urine

So what's wrong with CEE? Take a close look at the names. Notice the word "equine?" Yes, that equine! Premarin is horse estrogen! It is derived from the urine of pregnant mares, hence, its brand name. Premarin works great in female horses, just as Chevy parts work great in Chevys. But replacing human estrogens with horse estrogens may be asking for trouble, and here's why.

For the last several million years, the human female reproductive system has been running quite well on three separate estrogens: estriol, estrone, and estradiol, which occur in an approximate ratio of 90%:3%:7%1 (Fig. 1). Compare that with Premarin, which consists of estrone (75-80%), equilin (6-15%), estradiol + two other equine estrogens (5-19%).2 Notice that, in addition to having larger proportions of estrone and estradiol, Premarin also contains equilin and two other forms of estrogen found exclusively in horses.

The female human body contains all the enzymes and cofactors it needs to process estriol, estrone, and estradiol — when they occur in their natural human proportions. On the other hand, it has none of the enzymes and cofactors required to metabolize equilin and the other horse estrogens, nor does it have enough of these important substances to deal with the excessively large amounts of estrone and estradiol found in Premarin (or in the 100% estradiol "patch"). Horses, of course, are well equipped to handle CEE. The difference in reproductive hormones is just one of many differences between horses and humans. You may have noticed that horses also have four hooves and a mane, whereas human females don't.

It should come as no surprise, then, that the presence of Premarin in the human body induces a hormonal imbalance that can have important adverse consequences. To physicians who prescribe Premarin, this hormonal imbalance doesn't seem to carry much weight. After all, the drug works, doesn't it? But, as two leading reproductive physiologists point out, when women take Premarin, "Levels [of equilin] can remain elevated for 13 weeks or more post-treatment due to storage and slow release from adipose [fat] tissue. In addition, metabolism of equilin to equilenin and 17-hydroxyequilenin may contribute greatly to the estrogen stimulatory effect of [conjugated estrogen] therapy." Another metabolite of equilin, 17- -dihydroequilin has been found to be eight times more potent than equilin for inducing endometrial growth, a possible precursor to cancer.3

As a result, Premarin produces "estrogenic effects" that are much more potent and longer lasting than those produced by natural human estrogens.

This explains why so many women feel "unnatural" on Premarin, why Premarin causes so many side effects and discomforts (see box). It even explains why Premarin has been associated with a significant risk of breast and endometrial cancer, because one of the primary effects of equilin, estradiol and estrone is to promote the growth of tissue in the endometrial (uterine) lining and also in the breast. This growth is important for preparing the premenopausal body for pregnancy and lactation, but if some of that tissue becomes cancerous or precancerous, look out. According to Premarin's official labeling, taking it for a year (without also taking progesterone; see box), increases a woman's risk of endometrial cancer by as much as 14%.2

Most conventional physicians, not to mention the self-serving pharmaceutical industry, are quick to rationalize the cancer and other risks of horse estrogens. Every treatment has its risks, they point out, but the risk of a postmenopausal woman dying of a heart attack or stroke if she doesn't take Premarin are far greater than her risk of dying from cancer or an osteoporosis-related fracture if she does.

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Editor's Note:

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These articles are not intended to diagnose, treat, cure, or prevent any disease. Always consult with a physician before embarking on a dietary supplement program.


  1. Schliesman B, Robinson L. Serum estrogens: quantitative analysis of the concentration of estriol compared to estradiol and estrone. Meridian Valley Laboratory. 1997;Kent, WA:Data on file. 

  2. Premarin® (conjugated estrogen tablets). Wyeth-Ayerst Company. Physicians' Desk Reference, 52nd Edition. Montvale, NJ: Medical Economics Company; 1998:3111-3113. 

  3. Barnes R, Lobo R. Pharmacology of Estrogens. In: Mishell D, Jr, ed. Menopause: Physiology and Pharmacology. Chicago: Year Book Medical Publishers, Inc.; 1987. 

  4. Heimer G. Estriol in the postmenopause. Acta Obstet Gynecol Scand. 1987;Suppl 139:1- 23. 

  5. Lauritzen C. Results of a 5 years prospective study of estriol succinate treatment in patients with climacteric complaints. Horm Metabol res. 1987;19:579-584. 

  6. Iosif C. Effects of protracted administration of estriol on the lower genito urinary tract in postmenopausal women. Arch Gynecol Obstet. 1992;251:115-120. 

  7. Utian W. The place of oestriol therapy after menopause. Acta Endocrinol. 1980;233 (suppl):51-56.

  8. Lemon H. Oestriol and prevention of breast cancer. Lancet. 1973;1:546-547. 

  9. Lemon H, Kumar P, Peterson C, Rodriguez-Sierra J, Abbo K. Inhibition of radiogenic mammary carcinoma in rats by estriol or tamoxifen. Cancer. 1989;63:1685-1692. 

  10. Lemon H, Wotiz H, Parsons L, Mozden P. Reduced estriol secretion in patients with breast cancer prior to endocrine therapy.JAMA. 1966;196:112-120.

  11. Follingstad A. Estriol, the forgotten estrogen? JAMA. 1978;239:29-30.

  12. The Writing Group for the PEPI Trial. Effects of estrogen or estrogen/progestin regimens on heart disease risk factors in postmenopausal women: The Postmenopausal Estrogen/Progestin Interventions (PEPI) Trial. JAMA. 1995;273:199-208.

  13. Lee J. What Your Doctor May Not Tell You About Menopause. New York: Warner Books; 1996. 

  14. Lee J. Is natural progesterone the missing link in osteoporosis prevention and treatment? Medical Hypotheses. 1991;35:316-318.

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Unbelievable!!!  I had forgotten this but a very wise older man told me years ago to avoid HRT as some were made from the Urine of pregnant mares.  AND how do they collect the urine???  He told me that there are ‘factories’ in Canada??? where the mares are kept in a permanent state of pregnancy having their urine collected.  They live about two years never having seen sunlight.  If this is true then it is abhorrent!  Does anyone know anymore on this matter??  Julie

Estriol does not constitute 90% of the total estrogens in the body. This is wrong info. It is present in maybe 0.9% to 2% in non-pregnant women. Estradiol is the main estrogen made by the ovaries wheras estriol is made by placenta and by fetal liver and adrenals and thus can only be detected in any significant quantity in pregnant women.
But, this is not say that estriol supplementation is bad. From what I have read there is scientific validity to suggest (not same as proven) it can do some good.

Hi me again!  Doctor prescribed Premia-Continuous Tab 2.5mg for me.  I checked out the composition of this medication - if interested have a look at -  This is the site for AMS (Australian Menopause Society) Guide to Equivalent HRT doeses which will give you the composition of all different HRT medications.  Premarin/Premia is made from Conjugated EQUINE oestrogens - says it all I think.  Needless to say I will NOT be taking this under any circumstances - cheers Julie

that is animal cruelty i love horses and all animals that is inhumane for someone to do that to a horse there is better ways thank goodness i do not need hormone pills they need to stop what they are doing

Horses have had this done to them for the past 65 or more years.  As far as I can find out no one had a clue as to what it might cause.  When it was put on the market I believe doctors referred to it as a a pill that could keep a middle aged woman forever young.  Of course every one jumped on it and started taking it I’m sure it made a lot of MD’s rich at the time along with the drug company that produced it.  I have a good idea that no one connected any disease with the use of these drugs.  Many a persons grandmother, aunts or any female relative that died from cancer, or Alzheimer’s years after taking these drugs owes their illness to horse pee.  From What I understand too there are many unidentifiable elements in horse pee that scientists don’t know what they are.

Horse urine?
many hormones in mammals are relatively the same. rumors and assumption is usually a good way to promote a product or attack a company maybe scraped research funding or terminated you employment.
To blame cancer and other disease on any one product over a life time is easy but quite silly. If Premarin caused cancer in women, then we would say all women with cancer took Premarin. did lung cancer come from smoking or a life of pitching hay bales in the barn?
Do we know for sure there are factories? producing mare pee? There isn’t a huge amount of study cited in this, after several decades I would think there would be more on it. Like the people who insist a black out lab has discovered McDonalds has used 70% soy in the 100% beef burgers and calls the patented burger 100% beef the most attacked company in the world for food, could not lie about beef content. I am sure we would hear a lot more. Natural Progesterone is better yes, but the attacks here are like any, silly

These mares are kept permanently hooked to collect their urine and they are kept pregnant.  This is a miserable life for a horse that nature designed to run and be free to roam.  One fact that isn’t covered is that the foals of these mares are routinely left to die and are not kept with the mothers.  So in addition to the inhumane treatment of the mares, the foals that are produced are deprived of their mothers and typically are sent to slaughter or worse as young babies.  There are alternatives…for pete’s sake, use them.  Don’t allow this cruelty to continue.

WOW! I just took my first Premia 2.5. That was a waste of $32! Now I have read this I will be heading back to the Clinic and getting something else, including a new doctor as my doctor is in her mid 30’s and really doesn’t have a clue about Menopause. I should have mentioned to the doctor that I am vegetarian and working toward vegan but somehow I don’t think she would have a clue about that either!

I am just so amazed that anyone would still even consider being on Premarin or Prempro - this is not what your body produces or atleast my body does not produce horse urine.  Bio-Identical Hormones are available and are the only safe way to manage your levels for optimal health. I have been on BHRT for almost 2 years and have never felt better - do your own research - find a BHRT specialist in your area and improve the quality of your life as I did..

I work with a MD in Florida and we specialize in this area. If anyone want more info please email me .(JavaScript must be enabled to view this email address) and I can sent you to reputable sites to do the correct research rather than what you are currently using.

I have never heard about this. I ensure you that this is the first time I am hearing something about horse urine. Do people really drink this stuff for solving menopause problems? I really do not think so. Medical billing and coding companies

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