Food Allergy vs. Intolerance: Differences, Tell-Tale Signs, and Effects

What do gluten, dairy, eggs, nuts, seeds, shellfish, caffeine, sulfites, FODMAPS, and amines all have in common? They are all common allergens, but are you allergic to them or intolerant? Our world is so full of variety that we are so much more likely to encounter allergens and intolerances. Modern medicine is expanding and evolving all the time, and research is ongoing, so the approach does change, but the 20 million people across the states with food allergies alone speak to the scale of this issue. Fortunately, healthcare is taking note; medical degrees, nursing degrees, and the online ABSN all cover allergy and intolerance, meaning the workforce is ready to cope. 


To understand the signs and effects that foods have on our bodies, we need to look at the mechanism upon which they work. The biggest difference is how the body responds. With an allergy, an immune response can be triggered by even the smallest amount of the offending allergen. Most of the time, your immune system works hard to keep you alive, fighting off nasty infections. However, an allergy to a certain type of food happens because the immune system is overreacting–what a drama queen. The immune system thinks it is in danger and begins fighting. It releases antibodies that tell your cells not to let the allergen in; the cells then flood your body with histamine. 

Think of histamine chemicals like front-line soldiers; once they receive the message from the runners (antibodies), they charge hard and fast at the offending allergen, trying to get it out of your body as fast as possible. The trouble is, your body can only produce so much histamine, which is why antihistamines are a common treatment for allergies, supplementing the natural supply. 

Right now, you may be wondering about Epipens, the small, stick-like devices that people who know they are allergic to something carry around in case of an emergency. These are used when an allergy is too severe for antihistamines to cope with. In severe cases, the body goes into anaphylaxis, when the immune system floods the body with chemicals that cause it to go into shock. Blood pressure drops and airways narrow, making breathing extremely difficult. This is when the Epipen comes in handy; it is a large dose of epinephrine, which opens airways back up and increases circulation. 



Unlike an allergy, intolerances do not involve the immune system; they affect the gut, digestion, and metabolism.  These troublemakers bypass the immune system completely, opting instead to affect the digestive system and metabolism.

Without immune involvement, intolerances are often harder to track down, and their symptoms are less dramatic but still disruptive. Rather than triggering a full-scale immune reaction, intolerances quietly sow seeds of discomfort throughout the gastrointestinal tract because they cannot be properly processed. They may induce bloating, cramping, diarrhea, or constipation, leaving you feeling like your stomach has been transformed into a turbulent sea.

Common intolerances like lactose intolerance are caused by a lack of the enzyme to process the specific food. The enzyme that processes lactose is called lactase. If your levels of this are too low, the colon and small intestine cannot process lactose.  

The big differences 

Peanuts are a classic example of allergy, but did you know they can also cause intolerance? These allergies are among the most common and severe food allergies, characterized by immediate immune responses to peanut proteins, resulting in symptoms like skin reactions, respiratory distress, and anaphylaxis. On the other hand, some people may experience peanut intolerance, leading to digestive discomfort, bloating, and gas after consuming peanuts or peanut products. 

While both of these will cause a level of distress to the body, the effect, treatment, and long-term management are very different for both. 

Treatment differences 

The primary goal for anyone with a food allergy is avoidance. Understand what you are allergic to and keep it out of your diet. People with severe allergies generally carry epinephrine devices as a backup, just in case they accidentally consume an allergen. Doctors’ check-ups are regular, and blood tests can be taken to check for allergies. For certain allergens, one can take ‘allergy shots. ’ These work in a similar way to traditional vaccines in that each shot contains a small amount of the allergen so that the body can learn to fight it over time. Unfortunately, these are not currently available for food allergies. On the bright side, research is mounting on this use. 

For intolerances, the approach is a little different; unlike an allergen, the ‘avoid at all costs’ approach is not necessary. That is not to say that avoidance is not a strategy; it is, but foods you are intolerant of generally won’t kill you. Those experiencing stomach distress that could be the result of an intolerance are usually asked to keep a food diary to assess which foods are associated with distress. Some intolerances, such as celiac disease, can be diagnosed by a blood test. Once you know exactly what foods trigger you, your healthcare worker can create a diet plan. A plan makes sure you avoid bad foods while maintaining a healthy diet; it can be adjusted over time to suit individual needs. 

Future treatment

There is a variety of emerging research looking to treat both intolerance and allergy. On the allergy front, there is research on immunotherapies that could act as a vaccine for food allergies. 

The ongoing trend of genetic research is looking at the heritability of food allergies and how we can predict what allergies a child will have. We can potentially use gene editing technologies like CRISPR to ‘delete’ food allergy genes. The Food and Drug Administration (FDA) approved the drug omalizumab, a monoclonal antibody that allows children with a multi-food allergy as young as 1 to consume peanuts, tree nuts, eggs, milk, and wheat without an allergic reaction. A 2023 study looked at the effect of supplementing certain probiotics to improve gut health for those with lactose intolerance; the findings show strong evidence that gut health can be drastically improved. 

The future is bright, research is happening, and changes will come. Long gone are the days when a peanut allergy could easily kill or a gluten intolerance would ruin someone’s quality of life.




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I'm Jethro. I'm a carpenter, and love to build things! You can find me in the garage or at work most days of the week.My sister is Crystal, who you might know from this very blog. Her son Johnny loves video games just as much as I do - so we have a lot of fun playing together!

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