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Bioidentical Hormones: A Detailed Handbook on the Uses and Effects of Man-Made Hormones

In this article, Flo answers your questions about what bioidentical hormones are and if they’re safe. Used to treat menopausal symptoms, osteoporosis, and insulin disorders, bioidentical hormones are often prescribed as a preventative measure.

Bioidentical hormones mimic the hormones found in your body and come from natural sources like plant estrogens or animal-based hormones. They are used to treat low hormone levels and as an alternative to traditional hormone therapy.

Bioidentical hormones are sometimes marketed as “natural,” but they might still have been commercially processed or scientifically modified. Drug companies produce these hormones in many applications, including pills, creams, gels, sprays, and vaginal suppositories. In this way, they are very similar to traditional or synthetic hormone replacement treatments. 

In the United States, some women choose “custom-compounded” bioidentical hormones for customized treatment of their symptoms. Many people believe compounded bioidentical hormones are more natural, safer, and more effective than traditional hormone replacement therapy. 

According to the North American Menopause Society (NAMS):

  • There are 1.4 million menopausal women in the United States who use compounded bioidentical hormones.
  • Forty percent of all prescriptions for hormone replacement therapy are custom-compounded.

A pharmacist can custom-compound hormone formulations based on your personal needs as determined by a saliva test. However, your hormone levels fluctuate throughout the day, so testing your saliva isn’t the most reliable method. A blood test is a more accurate way to test for sex hormone levels. Since sex hormones bind to proteins, blood tests can look at binding proteins to determine the proportion of hormones. Accurate information about your hormone levels is essential for getting the right dose of custom-compounded hormones.

Not all bioidentical hormones are approved by the Food and Drug Administration (FDA), and not all bioidentical hormones are custom-compounded. Most customized hormone compounds contain the FDA-approved 17β-estradiol form of plant-based estrogen. However, compounds often also use other ingredients, depending on the type of product you’re using. For example, creams, sprays, gels, pills, and patches may also contain other types of hormones, including estriol, pregnenolone, and DHEA. These bioidentical hormones have not been approved by the FDA.

The FDA makes sure that approved hormone replacement treatments are manufactured under carefully controlled and strictly regulated standards. Before being approved, scientists have to test and scrutinize treatments to prove their effectiveness, purity, and quality. Not all custom-compounded bioidentical hormone formulations have undergone such strict testing and regulation. It’s a good idea to be skeptical of some of the advertising claims of these products, and always ask your doctor if the bioidentical hormones you’re considering are safe.

Bioidentical estrogen 17β-estradiol is not the only hormone replacement approved by the FDA. Bioidentical progesterone, known as Prometrium, has also been approved by the FDA and is available in two formats. You can get it as oil-based micronized progesterone or vaginal progesterone gel. Bioidentical estrogen 17β-estradiol and Prometrium are sourced from plants. The same cannot be said for traditional or synthetic hormone replacement treatments, which contain estrogens identical to the ones sourced from pregnant horses. 

Your doctor can prescribe FDA-approved bioidentical hormones for hormone replacement therapy to treat symptoms of menopause. Use caution when considering custom hormone blends from compounding pharmacists that are not FDA approved. These compounds cannot be tested, and there’s no way of knowing if you’re getting the right dose for your symptoms and hormone levels.

As stated in its publication about bioidentical hormone therapy, “NAMS supports the actions of the US Congress, FDA, and other scientific organizations that have warned about the potential harm from compounded bioidentical hormones.”

Unlike traditional hormone replacement therapy, bioidentical hormones are derived from natural sources that are chemically similar to human sex hormones. For these reasons, they are extremely popular for the relief of symptoms of menopause.

When estrogen levels drop during perimenopause and menopause, you may notice some unpleasant symptoms like: 

  • Hot flashes
  • Night sweats
  • Vaginal dryness
  • Loss of libido
  • Discomfort during sex
  • Trouble sleeping
  • Lack of energy
  • Fatigue
  • Loss of muscle mass
  • Weight gain
  • Foggy mind
  • Fluctuations in mood
  • Memory loss

Other hormonal changes occur as you age, affecting your progesterone and testosterone levels too. Many people choose hormone replacement therapy to help treat these symptoms. Hormone replacement therapy can help stabilize your hormones so you can get back to feeling like your usual self again. 

While there are many benefits to hormone replacement therapy, it also comes with risks and side effects. So consider your options carefully, and speak with your doctor for the best advice on how to proceed.

When it comes to hormone replacement therapy, talk to your doctor to weigh all your options and consider the risks. Here’s some information to consider about the safety of bioidentical hormones: 

  • There is not enough scientific evidence to back up the advertising claims that bioidentical hormones are more effective than traditional hormone replacement therapy.
  • Custom-made compounds are made to order and cannot be tested under the same strict regulations as FDA-approved bioidentical hormones.
  • Compounding hormone formulations contain additional ingredients that may not meet FDA-regulated standards.
  • The saliva test is unreliable.
  • Dosage and purity cannot be determined to predict effectiveness.
  • Lack of FDA testing and approval increases safety concerns.

Any kind of hormone therapy comes with its risks, including: 

  • Higher risk of blood clots and stroke
  • Increased risk of gallbladder disease

The longer you use hormone replacement therapy, the higher your risk of developing heart disease and breast cancer. These risks increase with age. 

Some smaller studies have shown that bioidentical hormones are safer than regular hormone replacement therapy, and some doctors agree. However, the studies are not conclusive enough to put this matter to rest. More research is needed to determine if bioidentical hormones are safer than traditional hormone therapy. Both come with benefits and risks.

Some of the side effects of bioidentical hormones may subside after your hormone levels stabilize, but if the side effects linger, you should consult with your doctor. 

Common side effects of bioidentical hormone replacement therapy include: 

  • Increase in body weight
  • Blurry vision
  • Fatigue
  • Skin breakouts
  • Facial hair growth
  • Headaches
  • Tenderness of the breasts
  • Light menstruation
  • Stomach cramps
  • Bloating and upset stomach
  • Moodiness

You may also experience irritation and itchiness around the site of application, whether you’re using a patch, cream, gel, or injection.

Most doctors recommend that you limit your hormone replacement therapy to a maximum of five years. Stopping hormone replacement therapy suddenly can cause a dramatic return of menopausal symptoms overnight. Gradually weaning yourself off bioidentical hormones, with the help of your doctor, is the safest way to stop hormone replacement therapy.

Whether you’re starting or stopping hormone treatment, your doctor will closely monitor your hormone levels with regular check-ups to make sure your levels are in a healthy range for your physiology. You may need regular blood, urine, and saliva tests to determine your current hormone levels. 

Your doctor will explain when and how to stop taking bioidentical hormones. Do not try to stop on your own. Safely weaning off bioidentical hormones can take as long as three months. Be patient with yourself, get plenty of rest, and maintain a healthy diet to nourish your body. Make a note of your changing symptoms as you stop treatment, and see your doctor regularly through this transition.

Bioidentical hormones have been shown to relieve common symptoms of menopause. As many as 40 percent of women on hormone replacement therapy in the United States use them. However, that doesn’t mean bioidentical hormones are risk-free. Any course of hormone replacement therapy has risks and side effects. Make sure you review all your options and talk to your doctor about your best course of action. 

1. Cleveland Clinic: Bioidentical Hormones

2. Mayo Clinic: Bioidentical Hormones

3. Mayo Clin Proc. 2011 Jul; 86(7): 673–680. DOI: 10.4065/mcp.2010.0714

4. The North American Menopause Society: Bioidentical Hormone Therapy

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