Do you get skin flushing or indigestion after alcohol or other foods? Do you feel worse after eating “healthy” fermented foods? Do you get headaches, nasal congestion, anxiety especially after eating? You may have histamine intolerance. Although most people are familiar with gluten and lactose intolerance, histamine intolerance tends to fly under the radar. It can mimic seasonal allergies, food allergies, anxiety, IBS and PMS making it hard to identify. Yet it appears to be a growing problem due to its link with gut imbalances, estrogen dominance, stress/adrenal issues and environmental toxicity.

Do you have histamine intolerance?
Because histamine is also involved in allergic reactions, many of these symptoms are also symptoms of true allergies, so make sure to rule that out (IgE “skin prick” test by an allergist). Reactions from histamine intolerance are generally not life-threatening, in contrast to some allergies, but they can still be alarming and negatively impact our lives. Here are some common symptoms of histamine intolerance:

  • Skin flush, hives, rash, itch
  • Headache/migraine (including premenstrual), brain fog, anxiety, depression, difficulty falling asleep or staying asleep
  • Nasal itch/congestion, throat itch/swelling, wheezing, shortness of breath
  • Diarrhea, nausea/vomiting, abdominal pain, bloating, reflux
  • Unstable blood pressure, racing heart, lightheadedness
  • Puffiness in hands
  • Menstrual cramps
  • Symptoms especially but not always after eating certain foods.

If you’ve taken antihistamine medications, you’re familiar with histamine. This is a chemical released by the mast cells of our immune system in response to an allergy, pathogen or other triggers. Mast cells act like protective guards; when triggered, they sound the alarm by releasing histamine into the bloodstream. Histamine can activate receptors in the gut, brain, heart, lungs and skin. Your symptoms will depend on which set of receptors are activated. For example, in the gut, histamine stimulates the production of stomach acid. In the airway system, histamine stimulates airway constriction, runny nose and watery eyes. Histamine intolerance arises when, in the absence of a true allergy, histamine accumulates in the body, chronically triggering many of the above symptoms.

Histamine Intolerance: Too much IN and not enough OUT
Histamine plays an important role in protecting our body. In the brain, it helps to make us alert and focused (this is why some antihistamines can make you feel dopey). Histamine also helps our immune system fight foreign invaders. However, we run into trouble when we have chronic excess histamine. High histamine levels are due to too much histamine coming into the body (via food or produced by the body) and not enough being broken down.

Much like water in a bucket, small increases in histamine may not be noticeable until you reach a critical point where the bucket “overflows” and symptoms are triggered. Those with histamine intolerance have factors that tend to keep the bucket “full” so symptoms are more easily triggered.

Antihistamine medications such as Zantac (H2 antihistamine used for reflux) and Claritin or Benadryl (H1 antihistamines) can help reduce symptoms for some individuals. However, in addition to some potential side effects, continuous use can lead to more histamine production and greater need for medication.

Clearance of histamine is influenced by genetics and gut health
Two main enzymes are responsible for breaking down histamine in the body – HNMT and DAO enzymes. The activity of HNMT enzymes, found in the brain and all over the body, is more genetically influenced than DAO enzymes, which may be why we see high histamine symptoms run in families. DAO enzymes are produced in the gut and responsible for breaking down histamine that we ingest. Therefore damage to the gut can reduce DAO enzymes and reduce our ability to breakdown ingested histamine.

Causes of histamine intolerance

  1. Stress & Adrenal Dysfunction You may have noticed that when you feel stressed or anxious, you get a flushing of the face or a racing heart. Histamine contributes to these stress reactions. Chronic stress or adrenal dysfunction can lead to more frequent histamine activation contributing to histamine intolerance. Stress management practices such as breathing, meditation and acupuncture can be helpful for calming and retraining the nervous system. In addition, supporting healthy adrenal function helps to improve stress resilience and avoid triggering stress reactions.
  2. Estrogen dominance The modern lifestyle, which includes chronic stress and an increasingly toxic environment, contribute to higher estrogen activity in both men and women. Estradiol (the “strong” estrogen) can lead to greater histamine release and reduce histamine breakdown, leading to a greater risk of high histamine levels and histamine intolerance. This is likely why there’s a higher incidence of histamine intolerance in women and I suspect especially in perimenopausal women. More on estrogen dominance and how to address it here.Symptoms like headaches or migraines just before or with periods and even symptoms worsening just before ovulation can be a clue that histamine is involved. Severe menstrual cramps can also be linked to the histamine released by the mast cells in the uterus.
  3. Damage to Gut Lining “Leaky gut” or damage to the lining of the gut can result from the continuous use of common anti-inflammatory medications (NSAIDS like Ibuprofen, Advil, Aleve), chronic stress, food intolerances and sensitivities and gut yeast or bacterial overgrowth. As mentioned above, the lining of the gut produces the enzyme (DAO) that breaks down histamine, so a compromised gut, reduces our ability to break down the histamine that we ingest, filling up our “histamine bucket” quickly. This is why many histamine reactions like skin flush, indigestion, nasal congestion and headaches seem to be triggered by eating certain foods. This gut-histamine connection is likely the reason that face flushing (like rosacea) often improves when we improve gut health. More on the causes of gut inflammation and how to address it here.
  4. Other Triggers Temperature changes, insect bites, certain foods, exercise, natural day/night rhythms can affect the histamine levels in the body too. Also other genetic factors (beyond DAO and HNMT) can influence our histamine metabolism. These factors can aggravate symptoms in those who already have high histamine levels. The goal is not to eliminate histamine but rather to keep it in a healthy balance. With histamine intolerance, our goal is to find out why the body is constantly in this protective or hypervigilant state. Just like overworked security guards have difficulty identifying enemy invaders from friendly food deliveries, our overprotective body will start to sound the alarm on even harmless triggers. Unfortunately, the malfunctioning security system itself can cause symptoms that are annoying or downright debilitating to our lives.

Addressing the causes of histamine intolerance helps to “empty” the bucket and make us less susceptible to histamine-related symptoms. Nutrition and lifestyle modifications are powerful here. Read more about how to identify histamine intolerance and how to rebalance your system here.

In health,
Dr. Carin