Allergies and Intolerances: What Are the Differences and How Can You Manage Them?

Offered By One5 Health | Private GP | Clinic

In general practice we certainly talk about allergies more these days, this partly due to the incidence of allergies being on the rise in recent times, but there is also more awareness about allergies and the importance of managing them well.

Man surrounded by pollen in the air sneezing

This year marks the introduction of Natasha’s Law, a long overdue legal requirement for pre-packaged food to be labelled with ingredients and allergens which comes into effect in October 2021, after 15-year-old Natasha Ednan-Leperouse suffered a fatal allergic reaction from a shop bought sandwich in 2016.

This law will save lives.

There are lots of theories as to why allergies are more commonly seen these days but the reality is we don’t really know. We suspect that a general higher standard of living is a contributing factor, meaning that we are less exposed to pathogens and we therefore forfeit the stronger immunity that comes with this. But there is also some evidence to show that this may be linked to lower vitamin d levels within our population, poorer diet, delayed introduction of solid food to a baby’s diet and increased use of paracetamol.

Small baby sitting on grass being handed a dandelion in seed.

Here we cover everything you need to know to make know how to approach and get help with your own allergies.

Let’s Start with the Basics

An allergy is an immune response to an allergen, which can be anything from pistachios to pollen, dust to dairy.  Physiologically there are two types of allergic reactions which can occur, these are IgE mediated and non-IgE mediated. IgE mediated reactions cause an immediate onset of symptoms after exposure to an allergen, and non-IgE mediated which can cause a more delayed reaction within hours or days or even weeks of exposure.

Woman scratching red upper arm

Symptoms of allergic reactions can be varied from life threatening airway swelling also known as “anaphylaxis”, to skin rashes such as hives which are more commonly IgE mediated; and non-IgE mediated symptoms such as diarrhoea, vomiting, eczema.

So, the reality is allergic reactions can produce a variety of different symptoms sometimes quickly after exposure to an allergen, and sometimes days or weeks later, and so you perhaps start to get a feel for why the field of allergy is so complex.

Around this time of year one of the most common allergy we see in clinic is allergic rhinitis, also known as hay fever and this affects one in four adults in the UK.

It typically causes symptoms of a runny nose, sneezing, itchy or watery eyes and is often manged with a combination of:

  • antihistamines
  • nasal sprays
  • eye drops

Other practical measures such as:

  • washing clothes frequently
  • avoiding drying clothes outdoors
  • wearing sun glasses can sometimes help too

In more severe cases you can also notice fatigue, sinus congestion, cough and wheeze and you may then need other forms of treatment. People traditionally notice these symptoms around the start of spring but they can come on at other times of the year too, and some people can even be affected throughout the year depending on the allergen causing their symptoms and when it is most prevalent.

Young male self administering eye drops

Atopy is an umbrella term for eczema, asthma, and hayfever and these conditions can often all go hand in hand, and there is a genetic predisposition for these conditions so they often run-in families and increase the likelihood of allergy in general.

Although it is important to understand that eczema and asthma are not always allergic processes themselves, but they tend to occur alongside allergies, so when discussing with your doctor about potential allergies they will often ask you if you have a history or a family history of atopy, and now you know why.

Young female patient having telehealth appointment with her doctor at home.

Food Allergies

Food allergies is a vast and continuously evolving area. It is estimated that 2 million people living in the UK have a diagnosed food allergy and this again is on the rise, and even more so in children than in adults. This is aside from intolerances which are also very common and often confused with allergies.

In the case of a food allergy, an allergen will always trigger a reaction, in the case of an intolerance the reaction may vary from one day to the next. This means that an allergy is only an allergy if you get a response to an allergen every time you are exposed to that allergen, if you get a reaction sometimes and less so at other times then it is much more likely to be an intolerance.

Selection of raw foods that are attributed to allergies or intolerances.

Allergies require strict avoidance of the allergen in the long term which can sometimes lead to a very restrictive diet, and this may not be recommended in the case of an intolerance. Likewise, allergy testing can be misleading in the case of intolerances so it really is crucial to differentiate between the two.

A specific common childhood allergy that we are seeing more of is Cows Milk Protein Allergy which can affect babies who are both breastfed and bottle fed and requires either the strict use of alternative types of baby formula or in the case of breastfed babies, requires mum to follow a dairy free diet.

This can difficult to diagnose with some babies presenting if a very typical way with diarrhoea, bleeding in stool, irritability and poor growth and others with more vague symptoms such as constipation, fussing with feeds, excessive wind and colic like symptoms. To complicate this further CMPA can also be IgE and non-IgE mediated meaning that excluding cow’s milk form the diet can sometimes lead to a quick improvement in symptoms or sometimes it can take weeks to notice a difference, not an easy thing for exhausted parents with new-born babies to assess.

One5 Health's Top Tips for Allergies Awareness

Illustration of various allergies and intolerances


  1. If avoidance of an allergen leads to an improvement of symptoms this is evidence in itself and allergy testing may not be necessary
  2. Don’t confuse allergies and intolerances; treating intolerances as allergies can lead to unnecessarily restrictive diets which can have long term nutritional consequences, so always seek advice before restricting your diet
  3. There is good evidence to show that having a good and varied diet in pregnancy or while breastfeeding can reduce the incidence of allergies in your children
  4. If you are concerned about allergies in a baby always seek advice before making any dietary changes, a baby’s diet moulds their future; changes should only be made with appropriate guidance
  5. Speak to a doctor if you have any allergy related concerns, a problem shared is a problem halved


Want to keep learning?  Read more about the author, Dr Mehma Rai MBBS BSc (Nutrition) MRCGP DRCOG - One5 Health

Allergies and Intolerances

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