When we hear the word “histamine,” antihistamines are the first thing that comes to mind. These are medications that provide relief from allergies by modulating the immune response responsible for them. 

Most people aren’t aware of just how many functions histamines play a role in. From digestion to mental health, these chemicals have the potential to either make us feel great or miserable. 

Hormones are one aspect of health in which we don’t often consider histamines. However, emerging research shows a surprising connection. High levels of histamine are implicated in estrogen dominance, providing women a promising new treatment avenue if all other efforts have failed.


Histamines are chemicals the immune system makes to ward off allergens. They cause the all-too-familiar springtime symptoms: sneezing, watery eyes, and itchiness. While these reactions are uncomfortable, they’re actually a sign that our bodies are trying to keep us safe. 

When we come across an allergen, a chain reaction starts in our immune system to protect us. Firstly, a signal is sent to mast cells located in the skin, lungs, nose, mouth, gut, and blood. These cells are where histamines are stored, so the immune system is requesting their release. (1.)

Upon exiting the mast cells, histamines increase blood flow to the surrounding areas. This leads to inflammation, which other chemicals from the immune system rally to take care of. Finally, the histamines settle at spots in the body known as “receptors”. 

This entire process causes thin walls of the affected areas, called membranes, to secrete mucus. A runny and/or stuffy nose, sneezing, coughing, and itchiness are all common symptoms as a result. 


Histamines cause different reactions in the body depending on where they are located and the specific receptors involved. They can be found from the brain all the way down to the gut, serving as both neurotransmitters and immunomodulators. 

  • H1

These histamines are found in smooth muscles. These muscles form the supporting tissue of blood vessels and hollow internal organs such as the stomach, intestines, and bladder. H1 causes typical immune responses such as hives, difficulty breathing, and asthma. 

  • H2

H2 histamines are located in the gastrointestinal tract. An increase in this type of histamine leads to increased stomach acid production. 

  • H3

This type of histamine inhibits neurotransmitters like dopamine, GABA, and serotonin. High levels of H3 histamines have been implicated in mental illnesses such as anxiety and ADD. 

  • H4

H4 histamines are primarily found on immune cells and tissues such as the spleen, bone marrow, thymus, and peripheral blood leukocytes. They are also located in the colon, lungs, liver, and epicanthus. Stimulation of the H4 histamine receptor results in the movement of eosinophils and increases molecular adhesion. (2.)


Humans naturally produce histamine, along with an enzyme called diamine oxidase (DAO.) DAO’s job is to break down the histamine we consume in foods. Oftentimes, what we call ‘histamine intolerance’ has nothing to do with histamine at all but is instead a DAO deficiency. Potential reasons for low DAO include: 

  • Foods that block DAO or trigger a histamine release 
  • Medications that prevent DAO from being produced or block its functions
  • Digestive disorders such as intestinal permeability or inflammatory bowel disease
  • Foods with extremely high histamine levels that cause DAO to perform incorrectly
  • Bacterial overgrowth in the intestines that causes histamine overproduction 


Despite what its name implies, histamine intolerance does not actually mean an intolerance to histamine – it simply indicates too much has been produced. When this happens, a variety of symptoms associated with allergic reactions can arise. These include: 

  • Headaches or migraines 
  • Nasal congestion or other sinus issues
  • Fatigue
  • Hives
  • Digestive distress
  • Irregular menses
  • Nausea
  • Vomiting
  • Insomnia
  • Brain fog

And, in severe cases: 

  • Abdominal cramping
  • Swelling 
  • High blood pressure
  • Irregular heart rate 
  • Anxiety
  • Difficulty regulating body temperature
  • Dizziness


Estrogen is the primary female sex hormone. Along with progesterone, it helps regulate a woman’s menstrual cycle and keep the entire reproductive system functioning as it should. 

Hormones in general, but especially sex hormones, are very sensitive. When balanced, everything runs smoothly. It’s when one asserts dominance over another that the intricate dance becomes out of sync. 

There are two types of estrogen dominance: frank and relative. The former refers to estrogen levels that are overtly high, above laboratory ranges. Frank estrogen dominance is treated by detoxing excess estrogen from the body. 

Relative estrogen dominance, on the other hand, simply means that estrogen is elevated compared to progesterone. In this case, treatment is centered around raising progesterone rather than lowering estrogen. 


  • Weight gain, particularly in the hips, waist, and thighs 
  • Menstrual irregularities such as uncharacteristically light or heavy bleeding 
  • PMS 
  • Fibrocystic breasts
  • Uterine fibroids 
  • Fatigue
  • Loss of sex drive
  • Depression or anxiety 

As you can see, there is symptomatic overlap between the two conditions; especially noteworthy is that both may cause menstrual irregularities. This clearly shows that estrogen dominance and histamine intolerance are related, the mechanism behind which will be discussed later on. For now, the key takeaway is that a holistic approach is necessary when healing from either issue. Simply addressing one or the other will not provide lasting results because the entire feedback loop must be broken. 


  1. Certain hormonal cancers

Breast, uterine, and ovarian cancers are all potential complications of untreated estrogen dominance. Breast cancer is increasing at an especially rapid rate; one in eight women will be diagnosed in their lifetime. The strongest form of estrogen, estradiol, is stored in fat tissue. Estradiol is harder for the body to get rid of due to its potency. This can result in more circulating estrogen and, eventually, harmful metabolites. (1.)

  1. Autoimmunity 

Significant changes in estrogen levels, such as during childbirth and menopause, can contribute to autoimmune disease due to increased inflammation. The risk of developing autoimmunity can be minimized by avoiding xenoestrogens in plastic, beauty products, food, and water. 

  1. Thyroid disorders

Excess estrogen increases levels of thyroid-binding globulin, which is a protein that releases thyroid hormones into the bloodstream. These hormones are inactive when attached to TBG, and unavailability of active thyroid hormones can disrupt metabolic processes. 

  1. Candida overgrowth

Candida is a fungus that lives in the mouth and intestines, and its role is aiding in digestion and nutrient absorption. Beneficial at normal levels, candida can become pathogenic when overproduced. When this happens, leaky gut can develop as the tight junctions lining the intestinal walls begin to break down. Candida multiplies when exposed to estrogen. This may explain why women taking birth control or hormone replacement therapy are more susceptible to yeast infections. 


Estrogen and histamine operate on a feedback loop of sorts, meaning they reinforce one another. Excess estrogen triggers histamine release, which only increases estrogen even more. Estrogen has also been shown to decrease DAO levels. This may explain why many women experience allergies during the luteal phase of their cycle. (3.)

High circulating histamine levels tell the ovaries to secrete more estrogen. It does this by stimulating the release of luteinizing hormone (LH), which causes increased estrogen production at ovulation. When women consume foods rich in histamine, the problem is further compounded and estrogen dominance can ensue. 


  • Avoid histamine-rich foods. These include:
    • Alcohol and other fermented beverages
    • Fermented foods and dairy products, such as yogurt and sauerkraut 
    • Dried fruits
    • Avocados
    • Eggplant
    • Spinach 
    • Processed or smoked meats
    • Shellfish
    • Aged cheese

Some foods do not contain high amounts of histamine, but still trigger its release. These include: 

    • Alcohol
    • Bananas 
    • Tomatoes
    • Wheat germ
    • Beans
    • Papaya
    • Chocolate 
    • Citrus fruits
    • Nuts (walnuts, cashews, and peanuts especially)
    • Food dyes and other additives

Certain foods also block DAO production, thus rendering the body unable to break down histamine. These foods include: 

    • Alcohol
    • Green tea
    • Black tea
    • Mate tea
    • Energy drinks 

Incorporating low-histamine foods may help with symptom relief. These include: 

    • Freshly cooked meat and fish
    • Fruits other than citrus
    • Eggs
    • Freshly ground nut butters with no additives
    • Gluten-free grains such as quinoa, rice, and amaranth 
    • Dairy substitutes such as coconut and almond milk 
    • Fresh vegetables (excluding eggplant, tomatoes, avocados, and spinach)
    • Cooking oils such as olive 
    • Herbal teas
  • Consider a B6 supplement 

One of the many roles of Vitamin B6 is increasing DAO production. You’ll also find this crucial nutrient in foods such as chicken, beef, and sunflower seeds. 

  • Improve your gut health 

Two specific probiotic strains, Bifidobacterium infantis, and Bifidobacterium longum, modulate the histamine pathway and therefore reduce production. 

  • Support liver detoxification 

The liver is the body’s detox center. From alcohol to the near 80,000 environmental toxins we come into contact with, every toxin must be filtered through the liver. Histamines are not toxic, per se. However, they do enter the liver after passing through the intestinal wall.  You can support the liver’s natural detoxification abilities via consumption of the following: 

  • cruciferous vegetables 
  • coffee 
  • green tea 
  • healing spices such as turmeric and ginger 
  • herbs like milk thistle. 



Rarely do we use the terms histamine and hormones in the same sentence. However, they have a closer relationship than most people realize. Estrogen dominance and histamine production operate on a feedback loop, meaning they reinforce one another. 

Reducing histamine production is a crucial aspect of lowering estrogen levels. Left untreated, it will only cause the hormone to be further secreted. The human body is one interconnected system and not a series of independent parts. This surprising connection provides a perfect example of this. Approaching illness from a functional rather than allopathic perspective is how we can achieve true healing.