Histamine Intolerance

What is histamine intolerance?

Histamine intolerance (HIT) is a condition where histamine builds up in your body. Histamine is a chemical that your body naturally makes and that’s present in some foods. Some experts think that if your body can’t break histamine down like it’s supposed to, it can build up and give you an upset stomach, headache or allergy symptoms.

This is different from histamine intoxication (also called histamine poisoning). Histamine intoxication usually happens as a food poisoning outbreak, affecting many people who ate the same high-histamine meal. Public health officials usually trace it back to certain types of fish.

Histamine intoxication is well-documented. But histamine intolerance is more controversial. Experts disagree about whether relatively low levels of histamine could cause symptoms, or if it’s more likely that irritable bowel syndrome or another condition causes symptoms that look like HIT.

Is histamine intolerance a food allergy?

No, histamine intolerance isn’t an allergy, even though it has some symptoms of allergic reactions. It’s sometimes called a “pseudoallergy,” as it looks similar to an allergy but has a different cause.

Is histamine tolerance a real thing?

The American Academy of Allergy and Immunology doesn’t currently recognize histamine intolerance as a condition. It’s a controversial issue.

Some experts suggest that if your body can’t break down histamine as well as it should, it can build up in your body and cause symptoms. But a 2023 study ruled out histamine intolerance in most people who thought it was causing their symptoms. The study’s authors and other experts suggest that other conditions cause symptoms that look like a histamine reaction.

What are the symptoms of histamine intolerance?

The symptoms of histamine intolerance are different from person to person. You may have one or more of these symptoms:

• Diarrhea.
• Bloating.
• Nausea or vomiting.
• Headache.
• Runny or stuffy nose.
• Shortness of breath (dyspnea).
• Itching.
• Rash or hives.
• Flushing.
• Low blood pressure.
• Irregular or fast heart rate (arrhythmia).
• Painful menstruation.
• Swelling of your lips, tongue or throat.

What causes histamine intolerance?

According to some theories, histamine intolerance symptoms could happen when your body can’t break down histamine. Histamine is a chemical signal that opens up your blood vessels, constricts your airways and gastrointestinal (GI) tract, and creates mucus. Mast cells in your mucous membranes release histamine and other chemical signals to help fight infections and regulate your organs.

Your body uses enzymes, mostly diamine oxidase (DAO), to break down histamine. If you have low levels of DAO and you eat something or take medication that increases your level of histamine, the histamine signals could cause symptoms like diarrhea, headaches, runny nose and hives.

Experts aren’t really sure what would cause some people to have low levels of DAO or an inability to break down histamine as they should. Some factors that might contribute include:

• Genetics. Some people might inherit a difference in their DNA that keeps them from breaking down histamine like they should.
• Conditions that affect your gut. Inflammatory bowel disease (IBD), parasitic infections and other conditions that affect the natural bacteria of your gut can change how your body breaks things down.
• Kidney and liver diseases. Chronic kidney disease, viral hepatitis and liver cirrhosis can reduce DAO levels in your body.
• Medications. Some medications interfere with your body’s ability to break down histamine.
• Age. Histamine intolerance is more common in people over the age of 40.

What foods trigger histamine?

Some foods contain large amounts of histamine. These include foods that involve an aging or fermentation process like wine, beer and cheeses. Other foods can cause your mast cells to release histamine (histamine liberators). Both of these types of foods can cause excess amounts of histamine in your body.

Some examples include:

• Alcohol (wine, beer and champagne).
• Processed meat.
• Cheeses.
• Sauerkraut.
• Vegetables (tomatoes, eggplant and spinach).
• Tropical fruit (pineapple, bananas, papaya and citrus fruits).
• Fish (mackerel, tuna, sardines and herring) and shellfish.
• Strawberries.
• Nuts and peanuts.
• Licorice.
• Chocolate.
• Pork.
• Egg white.
• Additives (like colorants and preservatives).
• Certain medications (including some antibiotics, blood pressure medications, diuretics, local anesthetics and prescription painkillers).

What medications increase histamine levels?

Certain medications can increase the amount of histamine in your body. They do this by either causing your mast cells to release histamine or reducing the amount of DAO that’s breaking down histamine in your body. They include:

• Contrast agents used in medical imaging.
• Muscle relaxants.
• Opioids/narcotics.
• Analgesics.
• Anti-inflammatory medications.
• Local anesthetics.
• Blood pressure medications (antihypertensives).
• Antiarrhythmics.
• Diuretics.
• Antiemetics/gut motility medications.
• Antibiotics.
• Mucolytics.
• Bronchodilators.
• H2-receptor antagonists.
• Cytotoxic medications (chemotherapy).
• Antidepressants.

How is histamine intolerance diagnosed?

There aren’t any proven ways to diagnose histamine intolerance, and not all providers recognize HIT as an official diagnosis. A provider can listen to your symptoms and try to diagnose you based on whether eliminating certain foods makes you feel better. Your provider might also perform various tests or procedures to help make a diagnosis. These include:

• Food diary. Keeping track of your symptoms and what you eat and drink can help identify what might be causing your symptoms. Sometimes, it’s a combination of foods, beverages or medications taken together that are the problem. Keeping a diary helps patterns emerge that you might not have noticed before.
• Allergy skin tests or blood tests. These can help you identify or rule out food allergies.
• Other blood tests. These can measure the amount of histamine or DAO in your blood and look for other issues.
• Histamine skin prick test. This is similar to allergy skin tests, but your provider pricks your skin with a small amount of histamine. If your skin is still reacting 50 minutes later, your body might not be breaking down histamine effectively.
• Histamine capsules. Your provider might have you take histamine capsules to test your reaction.
• Colonoscopy. A gastroenterologist can take look at your GI tract and take samples to rule out other conditions or look for high histamine or low DAO levels.

How do you treat histamine intolerance?

Treatment usually involves avoiding foods or beverages that cause your symptoms. To test what you can safely eat, you stop eating any possible triggers for a few weeks. If you haven’t had symptoms in that time, you start adding them back in one by one. If you start having a reaction to certain foods or combinations of foods but not others, you can avoid only the ones that make you react.

Medications for histamine intolerance

A provider may recommend medications that might help relieve symptoms of histamine intolerance, in combination with diet changes. They may suggest:

• H1 and h2 antihistamines. These block histamine receptors in various parts of your body so histamine can’t activate them. Taking antihistamines alone probably won’t stop your symptoms, but it could help in combination with dietary changes. H1 histamine inhibitors include cetirizine, loratadine and fexofenadine. They usually treat allergy symptoms. H2 inhibitors include ranitidine and famotidine. They usually treat digestive symptoms.
• DAO replacement. DAO supplements help your body break down histamine.
• Mast cell stabilizers. Medications like cromolyn sodium prevent mast cells from releasing histamine. Some food components called flavonoids, like luteolin and quercetin, have a similar effect.

What can I expect if I have histamine intolerance?

People with food sensitivities can usually manage their condition by changing their diet. In severe cases, taking DAO supplements or other medications can help. Sometimes the intolerance is temporary, and you can eventually go back to eating foods that you’d been avoiding.

When should I see my healthcare provider?

Talk to your healthcare provider if you have unexplained symptoms or you think you have a food intolerance. They can help you sort out whether it’s an allergy, intolerance or something else.

When should I go to the ER?

Go to the emergency room or call 911 if you have signs of anaphylaxis, including:

• Swelling of your lips, tongue or throat.
• Trouble breathing.
• Sudden drop in blood pressure (symptoms include weakness, dizziness, fainting and confusion).

What questions should I ask my doctor?

It might be helpful to ask your healthcare provider:

• Is this an allergy or an intolerance?
• How can I identify my triggers?
• What should I do if I have a reaction?