The female body needs estrogen for reproductive, cardiovascular and bone health. However, high levels of estrogen can cause irregular cycles or worsen conditions that affect reproductive health. Estrogen is an important hormone that regulates the reproductive system. It plays an essential role in other body systems as well. Estrogen levels rise and fall throughout life, often in sync with other hormones that control important body processes. An increase in estrogen stimulates sexual development during puberty. Together with the hormone progesterone, estrogen prepares the body for pregnancy. Estrogen levels that are too high or cause hormonal imbalances can cause problems. High estrogen can disrupt reproductive processes, cause unpleasant symptoms and increase the risk of certain conditions. Estrogen and progesterone work together to prevent the lining of the uterus from thickening. In some women, the body does not produce enough progesterone, resulting in “contradictory estrogen”. Unopposed estrogen is called estrogen dominance. Without the balancing influence of progesterone, estrogen can work overtime in the body and cause overgrowth of cells, including tumors in the lining of the uterus. It is rare for estrogen levels to be high due to overproduction. Estrogen levels are more likely to be high due to taking certain medications. For example, some patients may have low sex drive due to high estrogen levels, but this is most likely caused by taking birth control medication, not due to the natural estrogen produced by the body. Elevated estrogen not related to medication is most likely due to polycystic ovary syndrome before menopause. After menopause, high levels are more common with overweight or obesity. Symptoms of high estrogen levels include irregular periods or dense breast tissue. Various factors can contribute to high estrogen, including: Hormone therapy to boost low estrogen levels can lead to an initial rise in estrogen levels. High body fat index. Adipose tissue secretes estrogen. Having a high percentage of body fat can lead to high estrogen levels. Stress. The body produces the hormone cortisol in response to stress. Producing large amounts of cortisol in response to stress can reduce the body’s ability to produce progesterone. Alcohol. Drinking alcohol can increase estrogen levels and decrease the body’s ability to break down (metabolize) estrogen. Liver problems. The liver breaks down estrogen and eliminates it from the body. If it is not functioning properly, high levels of estrogen can build up in the body. Too few digestive enzymes, too many bad gut bacteria (dysbiosis),low levels of magnesium and increased dietary fiber can prevent the liver from removing excess estrogen. Synthetic xenoestrogens. These are chemicals found in the environment that act like estrogen once they enter the body. They can increase estrogen levels. Xenoestrogens include bisphenol A and phthalates. Both chemicals are used in various plastics. Xenoestrogens can also be found in pesticides, household cleaning products, and some soaps and shampoos. References: 1. Marquardt RM, Kim TH, Shin JH, Jeong JW. Progesterone and estrogen signaling in the endometrium: what goes wrong in endometriosis?. (https://pubmed.ncbi.nlm.nih.gov/31387263/) Int J Mol Sci. 2019;20(15):3822. 2. Neuhouser ML, Aragaki AK, Prentice RL, et al. Overweight, obesity, and postmenopausal invasive breast cancer risk: a secondary analysis of the women’s health initiative randomized clinical trials. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5070941/) JAMA Oncol. 2015;1(5):611-621. 3. Patel S, Homaei A, Raju AB, Meher BR. Estrogen: The necessary evil for human health, and ways to tame it. (https://pubmed.ncbi.nlm.nih.gov/29573619/) Biomed Pharmacother. 2018 4. Smy L, Straseski JA. Measuring estrogens in women, men, and children: recent advances 2012-2017. (https://pubmed.ncbi.nlm.nih.gov/29800559/) Clin Biochem. 2018;