Intolerances vs Allergies

The difference between an intolerance and an allergy?

It is almost seen as trendy for some people to claim they have an intolerance or allergy, thanks to the rise in gluten-free diets, the idea that dairy causes acne and that soy is hormone-ridden, amongst other things. For example, someone eating lots of chocolate over Christmas and getting spots may blame their poor skin on the dairy from the chocolate and claim they have an intolerance or allergy, ignoring the fact that they have been drinking much more than usual and perhaps have passed out before washing their face..

With such claims being spewed out so frequently, it’s no wonder individuals take to avoiding these foods, normally in the form of feigning some form of allergy or intolerance.

Furthermore, in light of the recent confessions from Burger King about their new “plant-based” item, it is important to understand how critical allergies can be.

But what is the difference, and why is it so important that this is known?


An intolerance is defined by the NHS as a ‘difficulty digesting certain foods and having an unpleasant physical reaction to them’, the unpleasant physical reaction normally manifesting as stomach pain, bloating, wind and/or diarrhoea, and skin rashes. These tend to occur a few hours after consuming the intolerable food.

Intolerances are normally diagnosed by running food elimination diets, whereby an individual excludes food items one by one and keeps a record of what they’ve eaten and how they feel after eating it, looking for any patterns of symptoms with particular foods.

Intolerances can be painful, but are rarely severe and never fatal.


Allergies are very different to intolerances, and can often be fatal (i.e. the Pret fiasco of 2018!). An allergy is defined by the NHS as ‘a reaction produced by the body’s immune system when exposed to a normally harmless substance’. There are 14 ‘major’ allergens, which are always listed in bold on ingredients lists. These are: Celery, Gluten, Crustaceans, Eggs, Fish, Lupin, Milk, Molluscs, Nuts, Peanuts, Sesame Seeds, Soya, and Sulphur Dioxide.

Allergies occur when antibodies deem a harmless protein on food/drink, or any substance to be harmless. This triggers the body’s immune system to try to ‘fight off’ the “harmful” substance, leading to symptoms such as sneezing, a runny/blocked nose, red/itchy/watery eyes, wheezing and coughing, a red, itchy rash and worsening of asthma or eczema symptoms.

Severe allergic reactions are known as anaphylaxis – these are extremely serious and can be fatal, and always need some form of medical intervention (whether that be via EpiPen or an A&E trip). Anaphylaxis symptoms include: feeling lightheaded/faint, breathing difficulties, wheezing, a fast heartbeat, clammy skin, confusion and anxiety, collapsing/losing consciousness, and sometimes hives, feeling/being sick, swelling or stomach pain.

Symptoms of allergies and intolerances have very little overlap, and so can often be determined by assessing the symptoms an individual is presenting with.

So why is it so important to understand the difference?

Allergies can be fatal, whereas, as uncomfortable as symptoms of intolerances can be, the intolerance itself is never fatal. Therefore, it is greatly important the difference is known, as accidentally exposing someone to something they are intolerant to will, as stated, be uncomfortable, but it will not be fatal. Carelessness and/or laziness of restaurant workers, for example, could be fatal if they mistake an allergy for an intolerance – for someone with anaphylaxis, even a trace of the food they are allergic to could be fatal (again – Pret 2018!). Knowing the difference and being able to apply the terms correctly will start to reduce the carelessness exhibited by some around allergies, thinking that people are overreacting. ‘Intolerance’ and ‘allergy’ are not synonymous, so it is important to understand the differences and use the relevant term.

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