Mysterious rashes, seemingly random migraines, diarrhea, nasal congestion—these are all possible signs of histamine intolerance. This condition, marked by an overaccumulation of histamine in blood plasma, is not very well understood among conventional medical doctors. It is difficult to diagnose, challenging to treat and perplexing and frustrating for those who deal with it. Here are the answers to your most pressing questions about histamine intolerance.  

Q: First off, what is histamine?

A: Histamine is a chemical found in every cell of the body. Produced by white blood cells, it plays a key role in our neurologic, digestive and immune systems. Histamine helps communicate messages to the brain and break down food in the stomach. It is also released by the body in response to an injury or allergy, which is why you might take an antihistamine such as Benadryl to ease allergy symptoms like runny nose or watery eyes.

Additionally, histamine is found in a wide range of foods at varying levels. Tomatoes, spinach, citrus fruits and avocados are typically high in histamine; so are many fermented, aged and canned foods and beverages.

Q: What is histamine intolerance?

A: Most people can tolerate the amount of histamine typically ingested from food, likely because their bodies produce enough amine oxidases, enzymes that rapidly break down and eliminate the compound. Only about 1 percent of the population is histamine intolerant, and these people likely have low levels of histamine-clearing enzymes, which allows histamine to build up in their blood plasma and disrupt bodily functions.

So the issue is not that people with histamine intolerance are sensitive to histamine—it’s that their bodies can’t get rid of the histamine that comes in. This is also what happens to someone who is intolerant to lactose or FODMAPs, but it is different from a food allergy, which involves an IgE-mediated response. This is why the correct term is histamine intolerance versus histamine allergy or sensitivity.

Q: What causes histamine intolerance?

A: Most common among middle-aged adults, this condition is thought to be either genetic or linked to gastrointestinal disorders such as irritable bowel syndrome (IBS), inflammatory bowel disease, celiac disease or small intestinal bacterial overgrowth (SIBO). Certain medications can also inhibit histamine-clearing enzymes.

Q: What are the symptoms?

A: Symptoms of histamine intolerance can vary significantly person to person, but they often mirror those of a food allergy, including:

  • Headaches or migraines
  • Nasal congestion, sinus issues, runny nose
  • Fatigue
  • Hives
  • Rashes or eczema
  • Wheezing
  • Swelling of the face, hands and lips
  • Heartburn
  • Digestive issues such as diarrhea
  • Abdominal pain

Q: How is histamine intolerance diagnosed?

A: Unfortunately, there are no tests available to diagnose histamine intolerance. Since this is not a food allergy, traditional allergy tests will not detect it. But since the symptoms are often similar, you should first get tested for food allergies, as well as other potential underlying conditions such as celiac disease, IBS and SIBO.

Once other causes have been ruled out or addressed, the next step is starting an elimination diet with the help of a dietitian. For two to four weeks, you follow a structured meal plan that avoids both high-histamine foods and certain low-histamine foods thought to trigger the body’s production of histamine. Food intake and symptoms must be logged in a daily food diary. If your symptoms improve after the trial period, you may be histamine intolerant. Next comes the reintroduction phase, in which histamine-containing foods are added back to the diet gradually under a dietitian’s guidance to gauge which if any you can tolerate.

Q: Which foods must be avoided?

A: It is tough to measure the amount of histamine found in different foods because it varies significantly according to food composition, the type of bacteria present and the food’s age. Generally, though, fermented foods such as bread, sauerkraut, wine, beer, aged cheese and processed meats are high in histamine. Additionally, certain low-histamine foods may trigger the body’s release of histamine, spiking levels in the blood plasma.

Here is a starter list of foods histamine-intolerant individuals should avoid:  

  • Alcohol
  • Fermented beverages
  • Green or black tea
  • Canned foods
  • Overly ripened or fermented foods (aged cheeses, sauerkraut, products with yeast, stale fish)
  • Soured foods such as sour cream and buttermilk
  • Cured and processed meats
  • Smoked fish
  • Shellfish
  • Pickled vegetables
  • Legumes
  • Citrus fruit
  • Pineapple
  • Strawberries
  • Dried fruit
  • Avocados
  • Eggplant
  • Spinach
  • Tomatoes and tomato products (marinara sauce, ketchup)

Q: What foods can be enjoyed?

A: Again, this varies by individual, but here is a general list of foods histamine-intolerant people can often eat without having an adverse reaction:

  • Fresh fruits and vegetables not on the list above
  • Fresh or flash frozen chicken, meat
    or fish products
  • Milk or milk alternatives
  • Whole grains
  • Cream cheese and butter
  • Cooking oils
  • Non-citric fruit juice
  • Herbal teas

Q: What should I do if I suspect I am histamine intolerant?

A: Make an appointment with your health care provider for an evaluation as soon as possible.