Histamine Intolerance vs. Allergy: What’s the Difference (and Why It Matters)

Look up the symptoms of histamine intolerance and what do you find? Itchy skin, nose and eyes, breaking out in hives, runny nose, headaches, swelling… 

And what would you find if you searched for symptoms of an allergic reaction to food? That’s right - the same list!

Now look up the treatment for each. 

They’re completely different, aren’t they? 

Why?

Because there’s a key underlying difference between histamine intolerance and food allergy. 

Keep reading and I’ll walk you through what’s really happening inside of your body, of course, why it matters to be able to distinguish between them, and what you can actually do about each one!

One Key Difference Between Histamine Intolerance and Food Allergy

Knowing the difference between histamine intolerance and food allergy is critical. Not only for your peace of mind, but for the way you approach your treatment. 

So, what is it?

The cause!

You see, histamine intolerance develops when there is too much histamine flowing around your body. Histamine levels rise because there’s a defect in your ability to break it down effectively, or you’re just making too much of it at any given time (1). 

A food allergy develops as a result of an immune reaction. When the immune system is triggered by an allergen, it causes histamine to be released, which can also build up and cause symptoms. 

Let’s dive a little deeper into these two conditions. 

 

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Here’s The Body’s Respond to Histamine Intolerance vs Allergy

I’m sure you’re well aware of what happens when you’re living with histamine intolerance. As a quick recap, your body’s histamine load can increase over time if you’re deficient in the key histamine-degrading enzyme diamine oxidase (DAO), or your histamine levels rise with intake from food or from the production by bacteria living in your gut. When you’re not able to break it down effectively, histamine will bind to one of its four receptors, namely H1, H2, H3, and H4. Each of these plays a different role in your body, causing bothersome allergic-like symptoms. While these symptoms may feel overwhelming and seriously affect your quality of life, they’re typically not life threatening. 

An allergy, on the other hand, can be. 

An allergic reaction is the immune system’s response to a perceived dangerous threat. It’s usually towards a particular protein in food, ones you may find in nuts, fish, eggs or dairy, for example. 

When exposed, the immune system activates its key mediators, which include basophils and mast cells, to neutralize the threat. Both basophils and mast cells are specialized cells filled with chemicals that include cytokines, chemokines and histamine (2). When activated under the threat of causing tissue damage, they will release these chemicals, which then trigger various system responses. Histamine, while causing those familiar symptoms such as itching, swelling and tearing, is primarily released to increase blood flow to the area of danger to assist in bringing critical chemicals to the site. 

As more fluid reaches the area, swelling appears. It’s this swelling and fluid accumulation that is the most dangerous part of a true allergic reaction. The symptoms develop within minutes of exposure and can affect the airways and your ability to breathe making it a life-threatening reaction. 

As you can see, both histamine intolerance and food allergies can look the same, but the key difference is the cause and effect. 

Histamine Intolerance vs Allergy: How to Tell Them Apart

So, in short, you can’t rely on symptoms alone to differentiate between histamine intolerance and allergy. You need a detailed history of the events leading up to the symptoms and targeted testing to find out which it is. 

The history

As mentioned above, your symptoms will likely come on over time when you’re living with histamine intolerance. They’ll increase when your histamine levels rise, and lessen when your histamine load is lower. You’ll also typically have a range of other symptoms such as digestive distress, mood instability, sleeping difficulties and hormonal imbalances (especially in those who still have a uterus and/or ovaries) (3). 

When it comes to a food allergy, it’s likely when you’re exposed to the offending food you’ll need emergency treatment with epinephrine. It may seem like it’s the first time it has happened, but the truth is, you’ve already been exposed to the offending food at least once, and your body has deemed it a threat. When exposed again, your immune system jumps in to save the day… or is at least trying to!

Testing 

Unfortunately, there is no conclusive medical testing that is 100% accurate when it comes to getting a histamine intolerance diagnosis. You could test your body’s DAO levels, but the amount in your blood is not a true reflection of how much you’re making (4). There’s also a lack of research to suggest the blood levels that would be deemed normal or insufficiency, so while useful in some cases, it can’t be used for diagnostic purposes. 

A food allergy, on the other hand, can be diagnosed clinically. The standard usually involves a skin prick test, where you’re exposed to tiny amounts of various allergens on your skin. Should there be a clinically relevant increase in a specific compound produced by the immune system, called IgE, the test is positive (5). Of course, a positive test will always be combined with the thorough history of symptoms to determine the appropriate course of treatment. 

Testing for IgE when you’re living with histamine intolerance can be useful to rule out a true allergy to a food. Have a conversation with your family doctor to determine if allergy testing is right for you. 

Diet 

One of the best ways to determine if you’re histamine intolerant is to trial a low histamine diet. Because a significant amount of the histamine in your body comes from the food you eat, eliminating histamine-containing food is a safe and relatively easy way to lower your overall levels. 

I typically encourage my clients to try it for 2-4 weeks. It’s extremely helpful to keep a food and symptom diary during this time to determine your response. 

Even a small reduction in your symptoms can give you a great deal of information about your condition and the next steps to take. 

Ok, so this all makes sense on paper. But what would each look like in a clinical setting?

 

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Clinical Cases of Histamine Intolerance vs Allergy – Clearing Up Some Confusion

Case 1: 

AJ, a 23 year old woman has always experienced headaches when she has even a small glass of wine. More recently, she’s been under a large amount of stress as she’s started her first job at a busy law firm. Her meals aren’t regular and she tends to snack on the muffins and other pastries available around the office, especially around 3-4pm. Recently, she’s noticed an increase in bloating and abdominal pain. She’s breaking out in hives when she drinks kombucha, and had flushing and headaches when she enjoyed a cheese board with her friends on the weekend. 

Histamine intolerance or allergy?

This would be a case of histamine intolerance. Her histamine levels are rising due to stress and an irregular diet. It's pushing her body’s histamine limit and increasing symptoms when higher histamine food such as kombucha and aged cheeses are consumed. 

AJ would be encouraged to follow a low histamine diet with more planning and regular meals, and seek help for stress management. She could also trial a course of a diamine oxidase supplement to decrease her symptoms. 

Case 2:

HF, a 50 year old man isn’t a very adventurous eater. He always eats similar foods like beef, chicken, some basic vegetables, potatoes, rice and pasta. He knows he had some sort of food reaction when he was a lot younger but can’t remember exactly what it was. To celebrate his 50th birthday, he recently went on a cruise with his family and wanted to try something new at the lunch buffet station. He was excited as it looked like a really delicious exotic dish. While enjoying the meal, he noticed his tongue started to feel funny, he was clearing his throat a lot and it started getting harder for him to breathe. The on-board doctor was called, who administered him epinephrine. They discovered there was shrimp in the dish he had decided to try. After the medication, he quickly recovered and went back to enjoying the cruise, but stuck to his usual food groups. 

Histamine intolerance or allergy?

This is a case of a true food allergy. Shellfish is a common cause of anaphylaxis, and HF should avoid any forms of shellfish in the future. He was also encouraged to see his doctor about allergy testing when he got home, and would likely need to carry an epipen in future. 

Case 3:

SR, a 33 year old man developed severe diarrhea when he was travelling. When he got back home, he was still having unusual bowel movements so his doctor prescribed him a 3 week course of antibiotics. Following the course of antibiotics, he started getting severe digestive discomfort, headaches, slight wheezing as he breathed and itching skin within minutes of eating eggs. He had never had symptoms like this before. 

Histamine intolerance or allergy?

In this case it could be either. SR should go for allergy testing to determine if the gut infection and subsequent use of a long course of antibiotics triggered an adult-onset allergy to eggs. He could also lower his general intake of histamine by following a low histamine diet to determine whether an infection or antibiotic-induced change in his gut microbiome led to more histamine-producing bacteria flourishing. 

Now you know how to recognise histamine intolerance vs allergy, you may be wondering why it matters so much. 

The Real Reason You Need To Know if It’s Histamine Intolerance or Allergy

It might not seem important to distinguish between histamine intolerance and allergy if they look the same, but being able to tell them apart all comes down to safety. 

A true allergic reaction can cause anaphylaxis within minutes. Like you saw with HF’s case above, it can become a medical emergency due to the effects it has on your airways and ability to breath. You’ll need to carry an epipen in this case, and completely avoid your trigger(s) (6). 

Histamine intolerance, due to the slower onset, allows for more time to control the reaction. Like you saw with AJ’s case above, the symptoms worsen over time with more exposure to histamine. In this case, it’s unlikely you’ll need to carry an epipen or require immediate emergency care when you’re exposed to higher histamine foods. Of course, should there be any difficulty breathing, chest pain that doesn’t go away, fainting spells, or any other abnormal symptoms requiring emergency care, don’t hesitate to seek help. 

While one condition is more emergent than the other, both histamine intolerance and food allergies require long term management. With histamine intolerance, it’s about lowering your overall histamine load alongside working on finding and treating the cause. As it was in my case, histamine intolerance is a curable condition, as long as the cause is truly addressed. When it comes to food allergies, the long term management focuses on strict avoidance of the food allergen, education about cross contamination and keeping medication available and up to date. While there are cases of cure such as children growing out of their allergies or through controlled medical exposure therapy, it’s more likely to be a lifelong condition. 

Knowing these important differences between histamine intolerance and food allergy can be extremely helpful in how you move forward with its management. 

Speaking of, here’s a practical step-by-step guide for what to do if you or someone you know has a reaction to food. 

Taking Action: Histamine Intolerance vs Allergy

Step 1: Assess the severity and need for immediate action

If there’s any difficult breathing, or any change in level of consciousness, don’t wait. This is a medical emergency. 

Step 2: If it’s not an immediate emergency, take a detailed history

Think about valuable questions to ask such as when and why this may have happened before. Is there a known allergy to a certain food, or family history of an allergy? How much of the food and what type of food triggers the response? Is anything else going on (stress, change in diet, travel, taking a new medication)? Answers to these questions all provide helpful information to your healthcare provider in determining whether it may be histamine intolerance or allergy. 

Step 3: Test (if you can)

If there is evidence of an allergy, set up IgE allergy testing with your healthcare provider. If you believe your symptoms are as a result of histamine intolerance, use this step-by-step at home histamine intolerance test method to better understand if you're histamine intolerance.

Step 4: Take the necessary steps to prevent and reduce symptoms 

If you’re positive for an IgE allergy with reproducible symptoms to a certain food, follow the guidance regarding avoidance of triggers and taking the appropriate medication as per your family healthcare practitioner. If you’re histamine intolerant, lower your histamine load and focus on taking low histamine probiotics, DAO enzymes and natural antihistamines to keep histamine levels low, while addressing the root cause.

Now you know how to determine whether you’re dealing with histamine intolerance or an allergy. Remember, an allergy develops quickly and can be life threatening. Histamine intolerance develops over time and symptoms increase with increasing load. While an allergy can mean life-long management, histamine intolerance may have a cure; you just need to find out what the cause is!

References:

1. Comas-Basté O, Sánchez-Pérez S, Veciana-Nogués MT, Latorre-Moratalla M, Vidal-Carou MDC. Histamine Intolerance: The Current State of the Art. Biomolecules. 2020 Aug 14;10(8):1181.
2. Calvani M, Anania C, Caffarelli C, Martelli A, Miraglia Del Giudice M, Cravidi C, Duse M, Manti S, Tosca MA, Cardinale F, Chiappini E, Olivero F, Marseglia GL. Food allergy: an updated review on pathogenesis, diagnosis, prevention and management. Acta Biomed. 2020 Sep 15;91(11-S):e2020012.
3. Kovacova-Hanuskova, E., Buday, T., Gavliakova, S., Plevkova, J. Histamine, histamine intoxication and intolerance. 2015. 43(5):498-506. 
4. van Odijk J, Weisheit A, Arvidsson M, Miron N, Nwaru B, Ekerljung L. The Use of DAO as a Marker for Histamine Intolerance: Measurements and Determinants in a Large Random Population-Based Survey. Nutrients. 2023 Jun 26;15(13):2887.
5. Anvari S, Miller J, Yeh CY, Davis CM. IgE-Mediated Food Allergy. Clin Rev Allergy Immunol. 2019 Oct;57(2):244-260.
6. Muraro A, Worm M, Alviani C, et al; European Academy of Allergy and Clinical Immunology, Food Allergy, Anaphylaxis Guidelines Group. EAACI guidelines: Anaphylaxis (2021 update). Allergy. 2022 Feb;77(2):357-377.