Food Allergy vs Food Intolerance – Do you know the difference? (2023)

Australia has one of the highest rates of allergies in the world, but what is the difference between a food allergy and a food intolerance? CARA BOATSWAIN investigates.

The free-from movement has certainly helped grow awareness of food allergies and intolerances, but many still mistakenly believe the terms are interchangeable. With one resulting in possible life-threatening reactions, the importance of understanding the difference is enormous.


“A food allergy is an immune system response to a food protein that, for most people, is actually a healthy nutritious food,” explains Maria Said, CEO of Allergy and Anaphylaxis Australia. “The immune system, for some reason, sees the food as a threat and the reaction that takes place can be mild for some, but for others, potentially life-threatening.”


The immune system can respond differently to allergens, which is why there are different types of food allergies.


IgE mediated food allergies cause the immune system to react abnormally when exposed to a specific food.

Reaction happens fast (usually within two hours of eating the food) and is the result of the immune system producing an allergen-specific antibody, immunoglobulin E (IgE), in response to proteins contained in the allergen.

This type of food allergy is more common in children than adults and only a small amount of the allergen is needed to trigger a reaction. Anaphylactic responses to food are usually a result of an IgE mediated food allergy.


In Australia the most common causes of IgE mediated food allergies are:

• cow’s milk
• egg
• peanut
• other tree nuts
• seafood
• wheat
• soy

While over 90 percent of food allergic reactions in Australia are caused by the above foods, the list isn’t definitive. Any food could cause an allergic reaction.

The good news is that around 80 percent of children grow out of allergies to milk and egg. Wheat and soy allergies are also less likely to persist into adulthood. Unfortunately, nut and seafood allergies tend to continue into adult life.


Allergic reactions to food fall into two categories: mild to moderate and severe, the latter can be a sign of an anaphylactic reaction.

Mild to moderate symptoms include:

(Video) Food Allergy & Food Intolerance - What's the Difference (Full Version)

• swelling of the face, lips and/or eyes
• hives or welts on the skin
• abdominal pain and/or vomiting
• eczema or rashes
• tingling mouth

Severe (anaphylactic) reactions include:

• difficult/noisy breathing
• swelling of the tongue
• swelling/tightness in the throat
• difficulty talking and/or hoarse voice
• wheeze or persistent cough
• persistent dizziness and/or collapse
• pale and floppy (in young children)


The Australian Society of Clinical Immunology and Allergy (ASCIA) warn that allergy tests alone are not sufficient to diagnose an IgE mediated food allergy. The three steps recommended by ASCIA are:-

a) consultation with medical practitioner detailing medical history
b) tests to identify IgE sensitisation to an allergy with results interpreted by a clinical immunology/allergy specialist
c) supervised oral food allergen challenge, if required

Allergy testing can show if a patient has (or hasn’t) been sensitised to an allergen. If not sensitised it means that an
IgE mediated reaction is unlikely. Unfortunately, allergy tests can not show how severe a response to a sensitised food will be.


Non-IgE mediated food allergies are caused by a reaction involving other components of the immune system apart from IgE antibodies. The reactions do not appear immediately after the consumption of the food. In fact, it can take up to 24 hours for symptoms to appear.

Non-IgE mediated food allergies are not as well understood as IgE mediated food allergies. The delay between consumption and reaction can make it more difficult to make the connection between the offending food and the symptoms.


The most common foods for non-IgE mediated food allergies are:

• cow’s milk (infants)
• soy proteins (infants)
• wheat (older children)


Non-IgE mediated food allergies do not result in anaphylaxis, so they are rarely life-threatening.

Symptoms are usually experienced in the gastrointestinal tract or on the skin. They include:-
• delayed eczema
• delayed vomiting and diarrhoea
• loose, frequent bowel actions
• blood or mucus in stools;
• irritability and unsettledness in infants


Diagnosing non-IgE mediated food allergies can be difficult. A lack of easily accessible blood or skin tests combined with the delayed reaction time doesn’t make the task any easier. An elimination and re-challenge diet is required to diagnose a non-IgE mediated food allergy. The process can take months to complete properly as usually only one food type is removed at a time.

Restricted diets can interfere with other diagnostic tests(such as the need to consume gluten while being tested for coeliac disease) and can lead to nutritional deficiencies. For these reasons it is very important that the elimination diet is undertaken with the support and supervision of a medical practitioner and dietitian.

(Video) The Difference Between Food Allergy And Intolerance

For more information on allergy testing visit the ASCIA website (


It is also possible to experience a mix of IgE and non-IgE mediated symptoms and signs. This is often seen in children with a cow’s milk allergy.


Food intolerances involve the digestive system and with the exception of sulphite and benzoate reactions, they do not cause anaphylaxis (severe reactions), that can be life threatening. Instead they are caused by reactions to food chemicals that irritate the nerve endings in different parts of the body.


Food chemicals can be found in many different foods and the response can differ from person to person. Some people are born more sensitive to food chemicals than others, but environmental triggers like changes to your diet or a nasty bout of gastro can alter the way your body reacts to food.

The food chemicals most commonly linked to food intolerance are:

• salicylates – found in many fruits, vegetables, herbs and spices, honey, tea, coffee, beer and wines

• amines – found in banana, avocado, tomato, cheese, chocolate, wine and other fermented foods

• glutamate – found in tomato, cheese and stock cubes

• preservatives – such as benzoates, nitrates and sulfites


There are a number of variables when it comes to food intolerance symptoms and reactions. The chemical you’re sensitive to, the degree of your sensitivity and how much of that chemical you consume in a day can all impact your response.

The time it takes for symptoms to develop can also vary with food intolerances. Some people see signs immediately, while for other is can take 12 to 24 hours.

The most common symptoms are:

• gastrointestinal issues
• nausea
• headaches
• recurrent hives and swelling
• reflux
• flu-like aches and pains

(Video) Food Allergy vs Intolerance - What's the Difference

Unlike a food allergy, where the consumption of even the tiniest amount of an allergen can product a reaction, food intolerances are dose dependent.

A small amount of a chemical-rich food may not produce a reaction, but larger amounts that exceed your dose threshold can. Food chemicals can also build-up in the body, so eating small amounts regularly is not recommended.


As there is no immune response involved in a food intolerance diagnosis can be tricky. “Food intolerances do not show up on allergy testing,” explains Said. “It can be a difficult concept to understand, as doctors also poorly understand intolerances.”

There is no reliable skin prick or blood test to diagnose a food intolerance. Food intolerances are diagnosed based on medical history and response to food elimination tests.

The best approach is to first see your doctor to:

• check for other conditions that may be causing symptoms.
• determine if diet is causing your symptoms.
• identify individual triggers to be avoided.


With similar symptoms and both requiring a food elimination diet for diagnosis, it’s understandable if you’re confused about the difference between a FODMAP sensitivity and food intolerance. However, the underlying cause of these conditions is very different.

FODMAPs (Fermentable Oligosaccharides, Disaccharides,Monosaccharides and Polyols) are a group of short-chain carbohydrates and sugar alcohols commonly found in the foods we eat. These carbohydrates are poorly absorbed in the intestine by some people and result in a range of gastrointestinal symptoms.

Studies have shown that people with irritable bowel syndrome (IBS) show an increased sensitivity to FODMAPs. 76 percent of people with IBS have reported an improvement in symptoms after following a low FODMAP diet.


FODMAPS can be found in many different foods, many of which are also high in food chemicals. While space constraints prevent us from listing all of the foods containing FODMAPs here are some those most commonly consumed:-

• oligosaccharides – wheat, rye, onions, artichokes, asparagus, leek, beetroot, legumes, beans, lentils, chickpeas, cabbage and Brussels sprouts.

• lactose – milk, ice cream, yoghurt, custard, dairy desserts, condensed and evaporated milk, milk powder, margarine and cottage, ricotta and cream cheeses. Lactose is represented by the “D” in FODMAP,for disaccharide (sugar).

• fructose – honey, apples, mangoes, watermelon, prunes, figs and high fructose corn syrup.

(Video) Food Intolerances vs. Food Allergies

• polyols – apples, avocado, mushrooms, cherries, lychees, nectarines, pears, plums, sorbitol, mannitol, xylitol, maltitol and isomalt.


Like a food intolerance, symptoms associated with a FODMAP sensitivity vary from person to person. Common
symptoms include:-

• bloating
• diarrhoea
• flatulence
• abdominal pain
• constipation


There is no test to definitely diagnose IBS. Doctors will review your medical history and conduct tests to rule out other conditions before looking at IBS.

If a low FODMAP diet is recommended you will need to follow an elimination diet to identify your food triggers. It is recommended that this is conducted under the guidance of a FODMAP-trained dietitian.

The FODMAPs that are triggers for one person, will be different to those that trigger symptoms in others. It’s definitely not a one size-fits-all approach.

It’s also important to remember that it’s a low FODMAP diet, not a no FODMAP diet. Once your triggers have been identified, you’ll be able to introduce FODMAP-containing foods that you don’t react to. This is important to ensure you are eating a balanced diet.

For more information about the low FODMAP diet and to try some delicious recipes, visit our sister publisher FODMAPPER.


If you are experiencing any of the above symptoms you may be wondering what to do next. First, make an appointment to see a medical professional before eliminating any foods from your diet. As previously mentioned, certain tests, like the test for coeliac disease, require you to regularly consume the allergen (eg.gluten/wheat), for the test to provide accurate results.

You could also start a food and symptom diary. This can be a helpful way to identify the foods you may be reacting to.

In a notebook, rule up the following columns:-

• time that you ate
• food or beverage consumed
• quantity
• symptoms experienced
• time you noticed/experienced symptoms

Each time you eat, write a response in each column. In the symptom category you might find it helpful to also rate the severity of the symptoms you’re experiencing using a scale of one to 10.

Your health professional may have a different diary system that you’ll need to adopt after your consultation, but in the meantime this will help you identify patterns and possible triggers to discuss with them.

(Video) Food Allergy or Food Intolerance? | Allergy Insider


What are 3 differences between food intolerance and food allergies? ›

However, there are clear distinctions. Food intolerance is a problem with digestion, whereas a food allergy is a problem with the immune system. Food intolerance may produce discomfort, but it is not life-threatening. A food allergy can cause a severe reaction like anaphylaxis, which can be life-threatening.

What are 2 signs of a food allergy or intolerance? ›

The most common food allergy signs and symptoms include:
  • Tingling or itching in the mouth.
  • Hives, itching or eczema.
  • Swelling of the lips, face, tongue and throat or other parts of the body.
  • Wheezing, nasal congestion or trouble breathing.
  • Abdominal pain, diarrhea, nausea or vomiting.
  • Dizziness, lightheadedness or fainting.
Dec 31, 2021

What are 3 possible signs of a food allergy? ›

Symptoms of a food allergy
  • tingling or itching in the mouth.
  • a raised, itchy red rash (urticarial) – in some cases, the skin can turn red and itchy, but without a raised rash.
  • swelling of the face, mouth (angioedema), throat or other areas of the body.
  • difficulty swallowing.
  • wheezing or shortness of breath.

What is a food allergy vs intolerance vs sensitivity? ›

The primary difference between an allergy, a sensitivity, and an intolerance is that an allergy is characterized by an immune system reaction to a substance, a sensitivity involves no immune response and an intolerance is characterized by the body lacking a chemical or enzyme needed to digest certain food.

What is the first step in identifying a food intolerance? ›

The best way to truly identify a food intolerance is to keep a detailed log with food you eat and symptoms you are having, then work with a registered dietitian to look at common foods or ingredients that would correlate with the types of symptoms you are experiencing.

What is the best way to identify a food allergy? ›

A blood test can measure your immune system's response to particular foods by measuring the allergy-related antibody known as immunoglobulin E (IgE). For this test, a blood sample taken in your doctor's office is sent to a medical laboratory, where different foods can be tested.

What are the 3 most common food intolerances? ›

The three most common food intolerances are lactose, a sugar found in milk, casein, a protein found in milk, and gluten, a protein found in grains such as wheat, rye, and barley.

What the 5 most common food intolerances are? ›

5 most common food intolerances
  • Dairy. This is one of the first foods we Naturopaths ask our patients to cut out — sorry! ...
  • Gluten. Gluten is a protein found in wheat and grains like rye and barley. ...
  • Egg. This can't be right, eggs are good for everyone! ...
  • Almonds and other nuts. ...
  • Yeast.

What is a common symptom of a food intolerance? ›

In our experience, the most common food intolerance symptoms range from eczema, IBS symptoms and bloating to joint pain, asthma, tiredness and anxiety.

What will destroy most food allergens? ›

Stomach acid will destroy the raw food allergens so the symptoms usually stop when you swallow the food. The allergy rarely progresses to a systemic reaction. Cooking the food will also destroy the allergen protein so canned and cooked fruits or vegetables rarely cause symptoms.

What happens if you keep eating food you're intolerant to? ›

Food intolerances affect your digestive system. People who suffer from an intolerance, or sensitivity, can't break down certain foods. They develop gas, diarrhea and other problems. An intolerance or food sensitivity is inconvenient but not life-threatening.

What can mimic a food allergy? ›

Another condition that may mimic food allergy symptoms is celiac disease. People with celiac disease are not able to tolerate gluten, a protein found in wheat and certain other grains. If your doctor thinks you have a food allergy, you'll probably see an allergist .

Can you tell the difference between allergy and sensitivity? ›

The difference between a food allergy and sensitivity is the body's response. When you have a food allergy, your immune system causes the reaction. If you have a food sensitivity or intolerance, the reaction is triggered by the digestive system.

Can a food intolerance turn into an allergy? ›

An intolerance should not turn into an allergy, because they affect different systems within the body. People can develop new allergies as an adult, but this does not mean it is related to a pre-existing intolerance.

Do food intolerances show up allergy tests? ›

A sensitivity to a food can be indicated in a skin prick test or a blood test, but does not always show a true allergy unless there has been a previous reaction to the food. These tests may offer clues about the causes of symptoms, but they cannot determine whether someone has a food allergy with absolute certainty.

Can a doctor do a food sensitivity test? ›

Food sensitivity testing is normally conducted in a doctor's office, clinic, or medical laboratory. The procedure depends on the specific test being used. Tests are prescribed by a doctor after reviewing your symptoms to determine the most probable sensitivity or intolerance.

Can I suddenly develop a food intolerance? ›

Yes you can. As you age, some researchers suggest that your immune system may weaken naturally, which may be why you're suddenly struggling with that creamy milkshake or feeling itchy after some grilled fish.

What are 5 symptoms of a food allergy? ›

Common symptoms of a food allergy include:
  • feeling dizzy or lightheaded.
  • itchy skin or a raised rash (hives)
  • swelling of the lips, face and eyes (angioedema)
  • coughing, wheezing, breathlessness, noisy breathing or a hoarse voice.
  • sneezing or an itchy, runny or blocked nose.
  • feeling sick or being sick.
  • tummy pain.
  • diarrhoea.

Is Benadryl good for food allergies? ›

Minor Allergic Reaction

In these cases, OTC or prescribed antihistamines such as diphenhydramine (Benadryl) may help reduce symptoms. These drugs can be taken after exposure to an allergy-causing food to help relieve skin redness, itching, or hives. However, antihistamines cannot treat a severe allergic reaction.

How can I test myself for food allergies? ›

Home tests for food allergies

Immunoglobulin E (IgE) testing can be performed at home. This test includes a finger prick kit so you can send in a small sample to a lab. This is a food allergy test that checks your IgE levels for a given food, similar to the test that your provider would send to a lab.

Can a food intolerance go away? ›

Food intolerances, which the American Academy of Allergy, Asthma & Immunology defines as “difficulty digesting a particular food,” are different than food allergies and often resolve on their own.

Can anxiety cause food intolerance? ›

As it is released, histamine causes swelling and irritation and again, stress is the culprit! It is stress that causes these mast cells to break down and release histamine all over the body including in the digestive system – which brings us back to food sensitivities.

Do food intolerances get worse with age? ›

Do food intolerances get worse with age? Food intolerances certainly change over time, for better or for worse. Some people may outgrow food intolerances, while others may develop them. As our digestive system ages, it becomes more difficult to break down foods.

Why am I suddenly intolerant to so many foods? ›

Maybe you've moved and are being exposed to different allergens, which trigger your immune system. A viral or bacterial infection could also flip that switch. Hormones can be a catalyst, too, especially in women. It's not uncommon to develop food allergies during puberty, pregnancy or menopause.

What is the number 1 food allergy? ›

Peanut allergies are among the most common and most fatal of the food allergies, causing anaphylaxis more often than the other four we mention.

How long after eating do you get food intolerance symptoms? ›

Food intolerance symptoms usually begin about half an hour after eating or drinking the food in question, but in some circumstances may not appear for up to 48 hours. Symptoms include nausea, bloating, abdominal pain, and diarrhea.

How long does a food intolerance flare up last? ›

When you have a food intolerance, symptoms usually begin within a few hours of eating the food that you are intolerant to. Yet, symptoms can be delayed by up to 48 hours and last for hours or even days, making the offending food especially difficult to pinpoint (4).

How long does a food intolerance episode last? ›

Symptoms of lactose intolerance usually begin between 30 minutes and 2 hours after consuming dairy. The symptoms last until the lactose passes through your digestive system, up to about 48 hours later.

Does microwaving destroy food allergens? ›

Cooking, even with high heat and other methods of food processing, does not reliably destroy food allergens, and doesn't ensure safety for people with food allergies.

What food causes 90% of food allergies? ›

These major food allergens make up 90% of food allergic reactions in the United States:
  • Milk.
  • Eggs.
  • Fish (e.g., bass, flounder, cod)
  • Crustacean shellfish (e.g., crab, lobster, shrimp)
  • Tree nuts (e.g., almonds, walnuts, pecans)
  • Peanuts.
  • Wheat.
  • Soybeans.
Feb 17, 2022

What are 90% of food allergies caused by? ›

Any food may cause an allergic reaction, but 90% of food allergies in children are caused by just 6 common foods or food groups—milk, eggs, peanuts, tree nuts, soy, and wheat. In adults, a similar percentage of serious allergies are caused by just 4 foods—peanuts, tree nuts, fish, and shellfish.

Can eating the same thing everyday cause food intolerance? ›

No, eating the same things every day – especially healthy foods – won't affect you adversely, and your body won't become toxic as a result. However, it is important to vary your diet to make sure that you are covering all your nutritional bases and that you're not getting too much of any one thing.

What autoimmune disease mimics allergies? ›

Idiopathic Mast Cell Activation Syndrome

MCAS is a condition in which the patient experiences repeated episodes of the symptoms of anaphylaxis – allergic symptoms such as hives, swelling, low blood pressure, difficulty breathing and severe diarrhea. High levels of mast cell mediators are released during those episodes.

What antihistamine is best for food allergies? ›

Use an over-the-counter antihistamine, such as diphenhydramine (Benadryl) or loratadine (Claritin), to treat mild symptoms. Read and follow all instructions on the label. Mild symptoms include sneezing or an itchy or runny nose; an itchy mouth; a few hives or mild itching; and mild nausea or stomach discomfort.

What are three common triggers of food allergies? ›

Eight things cause about 90% of food allergy reactions:
  • Milk (mostly in children)
  • Eggs.
  • Peanuts.
  • Tree nuts, like walnuts, almonds, pine nuts, brazil nuts, and pecans.
  • Soy.
  • Wheat.
  • Fish (mostly in adults)
  • Shellfish (mostly in adults)
Aug 18, 2021

What are the 7 common types of allergy symptoms? ›

Some of the symptoms of an allergic reaction include:
  • Itchy, watery eyes.
  • Itchy nose.
  • Sneezing.
  • Runny nose.
  • Rashes.
  • Hives (a rash with raised red patches)
  • Stomach cramps.
  • Vomiting.

Can an allergist tell you what you are allergic to? ›

Patch Test

This test determines what allergen may be causing contact dermatitis. Your doctor will place a small amount of a possible allergen on your skin, cover it with a bandage and check your reaction after 48 to 96 hours. If you are allergic to the substance, you should develop a local rash.

What does an allergy flare up feel like? ›

The release of tree pollens and outdoor mold spores are two of the most common spring allergy triggers. Spring allergy symptoms include all the classics like sneezing; runny, itchy or stuffy nose; headache, itchy and watery eyes; and dry cough.

Why are food intolerance tests not accurate? ›

IgG antibodies have not been shown to reliably identify either food allergies or sensitivities. Most people produce IgG antibodies after eating food. They are not specific to a person's sensitivity, although past or frequent exposure to a food may cause these levels to be higher.

How accurate are blood tests for food allergies? ›

Along with skin prick testing, blood testing is a common approach used to identify the allergens responsible for allergic symptoms. But while blood testing is accurate, no testing method will provide 100% certainty by itself. Data indicates that blood tests are approximately 95% accurate in providing negative results.

What is an allergy vs intolerance? ›

Summary. A food allergy occurs when the immune system reacts to a food which is usually harmless. Food intolerance occurs when the body has a chemical reaction to eating a particular food or drink.

What are the top 3 most common food allergies? ›

These major food allergens make up 90% of food allergic reactions in the United States: Milk. Eggs. Fish (e.g., bass, flounder, cod)

Can blood tests show food intolerance? ›

IgG blood test

This blood test looks at IgG antibodies to specific foods present in your blood. The test claims that an increase in IgG to a certain food indicates intolerance to that food. IgG antibodies to food are found in all healthy adults & children who do not show any symptoms.

Which foods cause 90% of food allergies? ›

A child could be allergic to any food, but these common allergens cause 90% of all reactions in kids:
  • milk.
  • eggs.
  • peanuts.
  • soy.
  • wheat.
  • tree nuts (such as walnuts and cashews)
  • fish.
  • shellfish (such as shrimp)

Can you suddenly become intolerant to certain foods? ›

Yes you can. As you age, some researchers suggest that your immune system may weaken naturally, which may be why you're suddenly struggling with that creamy milkshake or feeling itchy after some grilled fish.

How can you tell if someone has a food intolerance? ›

Symptoms of food intolerance

Most people who have a food intolerance have: tummy pain, bloating, farting or diarrhoea. skin rashes and itching.

Can an allergy test detect intolerance? ›

Reputable food allergy tests are available through physician specialists known as allergists or immunologists, but there are no reliable tests for food intolerances.

Does Benadryl help with food allergies? ›

Minor Allergic Reaction

In these cases, OTC or prescribed antihistamines such as diphenhydramine (Benadryl) may help reduce symptoms. These drugs can be taken after exposure to an allergy-causing food to help relieve skin redness, itching, or hives. However, antihistamines cannot treat a severe allergic reaction.

What is the most serious food allergy? ›

The most severe allergic reaction is anaphylaxis — a life-threatening whole-body allergic reaction that can impair your breathing, cause a dramatic drop in your blood pressure and affect your heart rate. Anaphylaxis can come on within minutes of exposure to the trigger food.

How long does it take to get food allergens out of your system? ›

Allergy to foods is commonly reversible. Symptoms often clear following 3-6 months of avoidance and nutritional therapy.


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