HRT Side Effects

HRT side effects of synthetic progestins/estrogens such as Provera, Premphase, Prempro, and Premarin.

What are synthetic progestins?

First, let's define progesterone. 

Progesterone is the oldest steroid hormone. It's about 500 million years old on the evolutionary scale. All vertebrates produce progesterone.  

In women, progesterone is a hormone produced in the ovaries. It is also produced by men, but in small amounts. 

Progesterone is an important hormone that contributes to the production of other hormones including estrogen and cortisone. Progesterone works together with estrogen to regulate a woman's reproductive cycle. 

Synthetic progestins are similar to progesterone in form and function. 

Synthetic progestins act like the progesterone that's naturally produced in your body, but are not the same. 

Differences between Synthetic and Natural Progesterone 

Synthetic hormones can actually lower a patient's blood level of progesterone. 

Synthetic hormone molecules differ in molecular configuration from hormones made in the human body therefore have side effects. 

Synthetic progestin is a medication that mimics the action of progesterone. 

Progesterone is a hormone that is created naturally in your body. 

Synthetic progestins do not occur naturally in your body. 

Synthetic Progestin side effects and advantages of bioidenticals

Prempro, Premphase, Provera and Synthetic Estrogen Premarin

Progestins (synthetic progesterones) are a popular alternative to BHRT because they are patentable and profitable. 

Estrogens and Progestins are one of the two major classes of female hormones. Estrogens are used primarily to treat the symptoms of menopause and states where the body is deficient in estrogen. 

Prempro, Premphase, and Provera are all synthetic progestins. 


Prempro contains a combination of estrogens and a progestin. 

Prempro is a medication some doctors prescribe to help you manage moderate to severe symptoms of menopause, like hot flashes, night sweats, and vaginal symptoms. 

Prempro contains estrogens and a progestin and is commonly used to treat women with a uterus who are undergoing natural menopause. 

Prempro, as with other forms of synthetic HRT, have serious potential side effects. 

These side effects range in severity from nausea to death. 


Premphase is made by the same folks who make Premarin and Prempro. 

Premphase works to replace or give more estrogen and/or progesterone so that it helps regulate the cycle and thus decrease symptoms of perimenopause. 

Along with being prescribed for menopause symptom relief, Premarin tablets can be prescribed for teenagers who fail to mature at the usual rate, and to relieve the symptoms of certain types of cancer, including some forms of breast and prostate cancer.


Premarin is used after menopause to reduce moderate to severe hot flashes. Also, to treat moderate to severe dryness, itching, and burning, in and around the vagina. 

Premarin also helps reduce your chances of getting osteoporosis. 

Premarin is made from horse urine. Premarin are synthetic estrogens. It's important to know taking estrogens increases the potential of getting cancer of the uterus. 


Provera is also prescribed to prevent abnormal growth of the uterine lining in women taking estrogen replacement therapy. 

Perhaps the most important fact you should know about about Provera is you should never take Provera during the first 4 months of pregnancy. 

The synthetic Progestins/Estrogens

Synthetic progestins/estrogens have many hrt side effects. 

Synthetic progestins/estrogens..

  • increase the risk of heart disease

  • increase the risk of breast cancer

  • are not protective against osteoporosis

  • cause depression

  • causes weight gain

  • cause fluid retention and edema

  • increase incidence of blood clots

  • increase anxiety and nervousness

  • increase hair loss and skin discoloration

  • increase the risk of dementia

  • can cause headaches

  • decrease thyroid action

HRT Side Effects of Synthetic Progestins

With conventional HRT, research has shown that Prempro, Premphase, and Provera all have potentially serious HRT side effects. 

Possibly the most serious HRT side effects include..

  • increases in the chance for strokes

  • increases in the chance for blood clots

  • increases in the chance for heart attacks

  • a possible contribution to Alzheimer disease

  • increases in the chance for breast cancer

› HRT Side Effects

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