Estrogen is an important hormone, and having too little of it can cause symptoms in both men and women. However, high estrogen can also cause symptoms, and may contribute to the growth of breast cancer cells in some women. To address these issues, some people turn to an estrogen blocker. Also known as an antiestrogen, this is a pharmaceutical or natural substance that reduces the effects of estrogen in the body.

What causes high estrogen?

High estrogen levels can be caused by taking estrogen. For example, women who are taking birth control pills may experience symptoms of high estrogen. Those who are on hormone replacement therapy (HRT) may also experience symptoms of too much estrogen. Adjusting the dose of the hormones may help to relieve these symptoms.

Obesity can also lead to high estrogen levels, because fat tissue makes estrogen. Women with polycystic ovary syndrome (PCOS) may also have high estrogen levels. Genetics play a role; for example, some people’s bodies express more of an enzyme called aromatase, which converts testosterone into estrogen. Liver disease and the use of certain medications can also lead to high estrogen.

What can too much estrogen do in women?

Women who have high estrogen levels may experience the following symptoms:

Heavy menstruation
Irritability and mood swings
Headaches
Sleep disturbances
Breast cysts
Endometriosis, a condition that leads to menstrual irregularities and pain
Fibroids, which are growths in the uterus
Gallbladder disease
Thyroid disorders

Women with high levels of estrogen may also have a higher risk of breast cancer.

Effects of too much estrogen in men

Men also need estrogen, but having too much of it can lead to certain symptoms, including:

Erectile dysfunction
Infertility
Gynecomastia (growth of breast tissue)

What are estrogen blockers?

Estrogen blockers are medications that reduce the effects of estrogen in the body. They may either inhibit the production of estrogen in cells, or they may attach to the estrogen receptor and block it. There are pharmaceutical estrogen blockers that can be prescribed by your doctor. Some people also use natural estrogen blockers; a few compounds have been shown to be possibly effective for this purpose.

Estrogen blocker pills (prescription)

Prescription estrogen blockers are used for some women who have undergone treatment for breast cancer, to decrease the chances of the cancer returning. Certain types of breast cancer are hormonally sensitive, meaning that estrogen causes the cancer cells to grow. Blocking estrogen helps to prevent the cancer cells from growing.

Estrogen blocker natural

Many people are wondering how to block estrogen naturally. There are a few different compounds that research has found may serve as natural estrogen blockers, including:

Stinging nettle (Urtica dioica) root
Saw palmetto (Serenoa repens)
African plum (Pygeum africanum)

There are also some compounds that are commonly used but have not been found to be effective, including lycopene (found in tomatoes).

If you’re considering using an herbal estrogen blocker, it’s important to get your hormone levels tested before and after you start using the compound. In addition, you should discuss your use of herbal medications with your doctor. Some herbal treatments can interact with prescription medications, so your doctor needs to be aware of everything that you’re taking.

Estrogen blocker side effects

Estrogen blockers can lead to significant side effects, including:

Weight gain
Low bone mineral density
Problems with memory or concentration
Changes in mood, such as anxiety, depression, or mood swings
Digestive issues, like nausea, constipation, or diarrhea

Estrogen blocker side effects in males

Besides the general estrogen blocker side effects, men may also experience erectile dysfunction and low libido from taking an estrogen blocker.

Estrogen blocker side effects in females

Women who are taking an estrogen blocker can experience symptoms similar to those experienced by women in menopause, including hot flashes and vaginal dryness.

Side effects of estrogen blocking herbs

The side effects of an herbal estrogen blocker can potentially be the same as for a prescription estrogen blocker. Whether a medication comes from an herb or a pharmaceutical, it can still have side effects. If you’re taking any type of estrogen blocker, then it’s important to watch out for side effects.

How do I know if I have estrogen dominance?

If you’re worried about your hormone levels or are considering taking an estrogen blocker, then the only way to know for sure is to get tested. Even if you have symptoms that are likely to represent high estrogen, you shouldn’t simply start taking an estrogen blocker without testing your levels.

To test your hormone levels, you can ask your doctor to order the laboratory tests that you need. Alternatively, you can order your tests at home. You can order your test and then go into a laboratory to get your sample taken, or you can select a home test kit. This is mailed to you, and you take a blood sample yourself at home using a fingerprick. Then you send your sample into a laboratory, and get your results online within a few days.

Sources

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Estrogen. National Institutes of Health. https://www.ncbi.nlm.nih.gov/books/NBK538260/. Accessed 25 July 2022.

Gervais NJ, Remage-Healy L, et al. Adverse Effects of Aromatase Inhibition on the Brain and Behavior in a Nonhuman Primate. J Neurosci. 2019 Jan 30;39(5):918-928. doi: 10.1523/JNEUROSCI.0353-18.2018.

High Estrogen. Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/22363-high-estrogen. Accessed 25 July 2022.

Hormonal Therapy: Managing Side Effects in Women. University of Rochester Medical Center. https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=34&contentid=26606-1. Accessed 25 July 2022.

Hormone therapy for breast cancer. Mayo Clinic. https://www.mayoclinic.org/tests-procedures/hormone-therapy-for-breast-cancer/about/pac-20384943. Accessed 25 July 2022.