In this article we’ll discuss what estrogen dominance is, typical signs and symptoms and how to treat the root cause for lasting change.
We’ll also cover a few scenarios where estrogen dominance is more likely, such as in perimenopause and for women using the hormonal IUD.
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What is estrogen dominance?
Estrogen dominance refers to a hormonal pattern where estrogen levels are unopposed by progesterone. This can lead to many unfavourable symptoms such as mood changes, headaches, heavy and painful periods and more.
Interestingly, estrogen levels do NOT have to be high for this hormonal imbalance to occur. If you experience low progesterone levels, then estrogen will still be left unopposed, meaning its effects are magnified and can cause or worsen symptoms of higher estrogen.
This is why at FUTURE WOMAN, we prefer to use the term “unopposed estrogen” to “estrogen dominance”.
How estrogen and progesterone should work together

In a healthy menstrual cycle, after the release of an egg at ovulation, we should see a healthy rise in progesterone levels and a small second peak of estrogen. In fact, progesterone levels should be more than 100x higher than estrogen in the second half of the menstrual cycle.
This ratio or balance between estrogen and progesterone is important, because these hormones counteract each other’s effects, for example:
- Estrogen thickens the uterine lining, while progesterone thins it
- Estrogen stimulates the brain, while progesterone calms it
- Estrogen increases cell division inside the breasts, while progesterone slows it
- Estrogen increases the release of histamine, progesterone has an anti-histamine effect
So you can see, there are many potential side effects when estrogen levels aren’t opposed by the calming effects of progesterone. Let’s look at what these symptoms might look like.
What are the symptoms of estrogen dominance?
Common signs and symptoms of estrogen dominance include:
- Heavy periods
- Painful periods
- Bad PMS
- Mood changes
- Breast pain or tenderness
- Weight gain
- Depression
- Fertility issues
- Miscarriage
- Irregular periods
- Endometriosis
- Fibroids
- Headaches or migraines
- Allergy type symptoms
- Hot flushes
Many of these symptoms are extremely common – in fact studies show that up to 90% of women will experience PMS type symptoms at some point in their lives.
However, common does not mean normal! If you’re experiencing any of these symptoms it’s important to test and understand the underlying drivers of estrogen dominance for lasting change. Let’s look at what these are.
The three drivers of estrogen dominance
When addressing estrogen dominance, it’s critical to look at the three underlying drivers of this common hormonal pattern. These are low progesterone, high estrogen and poor estrogen metabolism.
Let’s look at each one in turn.
1) Low progesterone
One of the main causes of estrogen dominance is low progesterone. In a healthy menstrual cycle, we should be making 100x more progesterone than estrogen. Low progesterone in the luteal phase of the cycle can leave estrogen unopposed, leading to estrogen dominance.
Progesterone’s main function is to prepare the lining of your uterus for a fertilised egg to implant and grow. If conception occurs, progesterone increases to support and maintain early pregnancy.
However, progesterone does so much more than its role in pregnancy and is vital for health and wellbeing.
- It has amazing calming effects on the body and the brain.
- It’s a natural antihistamine.
- It reduces inflammation and regulates immune function.
- It supports the thyroid.
- It supports a healthy brain, bones and breasts.
- It promotes a healthy menstrual cycle by providing important hormonal feedback. to the hypothalamus in the brain.
It’s important to note that progestins are not the same as progesterone. The synthetic hormone progestin is found in many hormonal contraceptives. However, it only acts like progesterone inside the uterus, helping to thin the lining. It doesn’t behave like progesterone elsewhere in the body, and therefore you can still experience estrogen dominance if you’re using progestins. We discuss this further in our section on estrogen dominance and the hormonal IUD below.

Causes of low progesterone
We see low levels of progesterone primarily as a result of lack of ovulation – this can be lack of ovulation every cycle or just during some cycles. It is important to note that having a regular cycle does not guarantee that ovulation took place.
We also see low progesterone levels when the quality of ovulation is poor and we have issues with the health of the corpus luteum.
Low levels of progesterone are increasingly common in our modern society, as they are closely linked to stress. Perimenopause is also a time when progesterone levels fall – in fact, it’s often the first hormonal change women experience even in their mid 30’s.
Reasons for lack of ovulation:
- Stress: As a response to stress, the stress hormone cortisol is made and released by the adrenal glands. Excessive amounts of cortisol may interfere with the hormones which control the menstrual cycle, resulting in irregular or absent ovulation. Stress also directly affects progesterone levels. Tyoically as cortisol levels increase, progesterone levels decrease. This means stress can lead to a progesterone deficiency, causing unopposed estrogen symptoms. Sources of stress for the body can include high perceived stress, over exercising and under-eating.
- Polycystic Ovarian Syndrome (PCOS): PCOS is a condition of androgen excess and other factors such as insulin resistance, and inflammation which prevent ovulation from occuring. This results in low progesterone.
- Hormonal birth control: The contraceptive pill suppresses our hormones and prevents ovulation occurring, resulting in low progesterone. With the hormonal IUD you may still ovulate, even if you’re not getting a monthly bleed, however this is less likely in the first years of use.
- Low thyroid function: A healthy thyroid controls our metabolism and hypothyroidism (low functioning thyroid) slows many of the body’s processes down. This causes changes to the menstrual cycle such preventing ovulation from occurring.
- Perimenopause: As our follicles become less responsive with age, we ovulate more sporadically, leading to low progesterone levels. This can lead to estrogen dominance, especially in the early stages of perimenopause.
Testing progesterone levels:
It’s important to test your progesterone levels if you’re experiencing symptoms of estrogen dominance. Unfortunately many standard hormone tests exclude progesterone, as they tend to test on Day 3 of the menstrual cycle when progesterone levels are at their lowest.
We recommend testing with a hormone test like the Advanced Hormone Test, which tests 5-7 days after ovulation specifically to capture progesterone levels at their peak.

2) High estrogen
You won’t be surprised to hear that a driving factor of unopposed estrogen is high estrogen levels!
Estrogen is one of the two main female sex hormones (the other being progesterone). Estrogen has many important roles to play in the body; primarily it is responsible for the development and regulation of the female reproductive organs. It also plays many other roles including being responsible for the growth and maintenance of the skeleton and the normal function of the cardiovascular and nervous systems.
Causes of high estrogen
Some factors can directly cause an increase in estrogen levels including
- Endocrine disrupting toxins: Synthetic xenoestrogens are endocrine disrupting chemicals which act like estrogen in the body, leading to higher levels of estrogen. BPA and phthalates are examples of xenoestrogens found in plastic but others can be found in cleaning products, pesticides and hygiene products such as shampoos. Find out more about Environmental Toxins and hormone health here
- Histamine: Estrogen can stimulate mast cells to release histamine whilst histamine stimulates the ovaries to make more estrogen, causing a vicious cycle. An enzyme called DAO which helps to clear histamine is also downregulated by estrogen, adding to the histamine-estrogen cycle. Find out more about the relationship between histamine and estrogen here.
- High body fat: The ovaries produce the majority of estrogens in women before menopause, however estrogen can also be made and secreted by white adipose tissue (fat tissue). So having a high amount of body fat can lead to high estrogen levels.
- Aromatase expression: Aromatase is an enzyme that converts androgens into estrogens. It is thought that some women can over express this enzyme, causing higher levels of estrogen. For example, there is some evidence that women with endometriosis highly express aromatase. This is also why women with PCOS can experience estrogen dominance.
- Perimenopause: In the early stages of perimenopause, estrogen can go on a wild rollercoaster ride, at times rising higher than at any other time in your reproductive life. Many typical perimenopause symptoms are related to estrogen dominance.
Testing estrogen levels
We talk about estrogen as one hormone, but in fact there are three estrogens: estrone (E1) is found most commonly in menopausal years, estradiol (E2) is the main estrogen in reproductive years and estriol (E3) is the main estrogen in pregnancy. Many standard hormone tests will only test estradiol, however any one of these three estrogens could be raised and cause symptoms.
We recommend testing with a comprehensive hormone test like the Advanced Hormone Test, which tests all three estrogens.
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3) Poor estrogen metabolism and detoxification
Hormone metabolism is an important aspect of our overall hormone health, but it’s often overlooked. But what is it?
Once our hormones have been used, they need to be packaged up and removed from the body via the liver and the gut. This happens in 3 distinct phases. If any one of these phases is impaired, it can lead to the reabsorption or reactivation of estrogen.
Estrogens are metabolised in the liver in two main phases – Phase I (hydroxylation) and Phase II (methylation, sulfation, and glucuronidation) – and then the gut in Phase 3.
We often describe estrogen detox like a bathroom sink – if you have issues with the tap (phase 1), the plug (phase 2) or the waste pipe (phase 3) then water can’t be cleared effectively. We also like this analogy because it makes it clear that when improving estrogen detoxification, it’s important to work backwards, i.e. starting from Phase 3.

Phase 1 Estrogen Detoxification
In Phase 1, estrogens are metabolised by detoxification enzymes and the resulting metabolites can move through three competing pathways. Some women may utilise one pathway more than others which can have an effect on symptoms.
- The 2-OH is considered the best estrogen metabolite due to its weak activity so you would be less likely to have symptoms of high estrogen.
- The 16-OH is a more proliferative estrogen metabolite which can be linked to high estrogen symptoms.
- The 4-OH estrogen metabolite is the most potent and can cause DNA damage.
If you have a stronger preference for the 16-OH or 4-OH pathway, then you’re more likely to experience symptoms of estrogen dominance. You can test your pathways in a comprehensive hormone test like the Advanced Hormone Test.
Genetics also plays a role in estrogen metabolism. There may be variations in some of your genes that encourage your estrogen down certain pathways that can result in symptoms of estrogen excess (eg: the CYP19A1).

Phase 2 Estrogen Detoxification
In Phase 2, the metabolites from Phase I are made water soluble, allowing them to move into Phase 3 and be eliminated from the body. Methylation is one of the key processes in phase 2 which transforms the estrogen metabolites into water-soluble compounds so they can be excreted from the body. This process involves the COMT enzyme.
Poor methylation in the body can lead to hormone imbalances, poor detoxification, poor sleep, mood changes and low energy.
Methylation can be affected by;
- Poor nutrient status: B6, B12, and folate are all needed for COMT function.
- Genetic SNPs: Genetic variations in the COMT gene may cause decreased enzyme activity and ineffective methylation leading to higher estrogen levels.
- Stress: Chronic stress has been shown to alter methylation.
Anything that can affect how well your liver functions can affect estrogen metabolism in Phase 1 and 2. Alcohol, caffeine and medications processed by the liver can affect how efficiently estrogen is metabolised.
Phase 3 Estrogen Detoxification
Phase 3 takes place in the gut and kidneys. The water-soluble metabolites can now be excreted by the kidneys in urine (this is why we test our hormones using urine samples instead of blood!) or the stool via bile.
Phase 3 can be affected by:
- Gut dysbiosis: In the gut microbiome there is a specific group of microbes called the estrobolome which help to remove estrogen from the body. However, if we have dysbiosis (an imbalance) of gut bacteria these microbes can release an enzyme called beta-glucuronidase which unpackages the estrogen that’s ready for elimination and recirculates it in the body. Medications, especially antibiotics and oral hormonal contraceptives, can negatively affect the estrobolome.
- Constipation: Estrogen is also packed up and excreted via the stool, so what happens when we have a slow transit time, or constipation, is that the estrogen can get reabsorbed back into the body, causing estrogen levels to rise. Constipation can be caused by gut dysbiosis, a lack of fibre in the diet, low hydration, medications or stress.
Testing estrogen metabolism
You can test your estrogen metabolism pathways, methylation and gut dysbiosis status with a thorough urine-based hormone test like the Advanced Hormone Test. Blood serum tests cannot detect these markers.
Estrogen dominance and perimenopause

Many people assume that when they start the transition into menopause (aka perimenopause), it is a decline in estrogen that is causing their symptoms.
However, in the early stages of perimenopause it’s actually progesterone that is the first level to drop as ovulation becomes more sporadic. Estrogen can actually fluctuate wildly up and down, sometimes rising higher than at any other time in our reproductive lives. Therefore estrogen dominance is extremely common in the early stages of perimenopause, resulting in many hallmark symptoms such as PMS, heavy periods, anxiety, sleep disturbances, migraines and hot flushes.
You can read more about the signs and symptoms of perimenopause and the four stages of perimenopause.
Perimenopause, HRT and testing
If you’re considering HRT in perimenopause, it’s important to test your hormones first to understand which hormones you need. Many women are prescribed estrogen hormone therapy in perimenopause, balanced by a synthetic progestin. However, as we have seen, it’s likely you’re experiencing high estrogen and low progesterone in early perimenopause, so this combination will just compound estrogen dominance, making symptoms worse.
Estrogen dominance and the hormonal IUD

Whilst the oral contraceptive pill suppresses hormones and ovulation to prevent pregnancy, the hormonal IUD does not fully suppress ovulation. It has other mechanisms of action to prevent pregnancy.
Some research suggests that ovulation occurs with hormonal IUD use about 15% of the time in the first year of use, rising to about 85% of cycles after the first year.
This means that most women still develop eggs and continue to produce the estrogen and testosterone associated with egg development. However, they do not produce the progesterone associated with normal ovulation because of the synthetic progestins in the IUD. This can cause estrogen dominance and symptoms may be seen at time of ovulation (normally mid-cycle) rather than in the second half of the cycle.
How to address estrogen dominance
If you suspect you might have high or unopposed estrogen, the first best step is to test your hormones and hormone metabolites with a comprehensive hormone test like the Advanced Hormone Test. This is important because symptoms of high estrogen can mimic symptoms of other hormone imbalances such as low progesterone.
It is also important to test to establish why you may have high estrogen, for example is it due to excess estrogen production or is it because you have poor methylation and phase 2 detoxification (meaning estrogen is being recirculated through the body)? Once we establish the root cause, then we can support the body in the correct ways.
In our FUTURE WOMAN Hormone Tests we look at many markers when investigating symptom of estrogen dominance/unopposed estrogen including;
- Your overall estrogen levels. This looks at three types of estrogen, including estriol, estradiol and estrone. This will give you a clear picture of what is happening with your overall estrogen, but also if you are low or high in any of the three main estrogens too.
- Your progesterone levels. It is important to look at your progesterone levels in comparison to estrogen. Estrogen levels may be normal but if progesterone is low, your estrogen is unopposed and can cause problems.
- Your estrogen phase 1 metabolites. Our FUTURE WOMAN Hormone Tests also look at the three estrogen pathways in phase 1 detoxification. These pathways are called 2-OH, 16-OH and 4-OH. It is important to understand the proportion of your estrogen moving through each pathway, as it can impact your symptoms.
- Your estrogen phase 2 metabolites. One of the other markers we look at is called methylation. This looks at how well you are detoxifying estrogen from the body in phase 2 detoxification. This result will show if it is too slow or fast which can affect total estrogen levels in the body.
- Markers for stress, gut dysbiosis and nutrient deficiencies. As we have seen these factors can contribute to high/unopposed estrogen and are tested with the Advanced Hormone Test.
Each of our tests comes with a personalised plan which will address your hormone imbalances in detail.
3 easy tips to reduce estrogen dominance
If you’re concerned about estrogen dominance, try these three simple steps:
- Test and address your unique hormone imbalances: Understand which hormone imbalance is driving your symptoms and address those directly with a qualified practitioner like those at FUTURE WOMAN. Is it low progesterone? High estrogen? Sluggish estrogen metabolism? Or all 3?
- Balance your blood sugar. Eating 3 balanced meals a day which are high in protein helps to keep blood sugar balanced. This in turn reduces stress on the body which can support progesterone levels via regular ovulation.
- Introduce freshly ground flaxseeds into your diet:. Ground flaxseed supports the removal of estrogen from the body in the stool. Add 1 tbsp of freshly ground flaxseed daily to smoothies, soups and stews.