Food allergy and food intolerances: the difference

Allergic reaction to peanuts, tree nuts, seeds and seafood persist in 80% of those affected
Allergic reaction to peanuts, tree nuts, seeds and seafood persist in 80% of those affected 

When my son was 6 months of age, in order to return to work, we weaned him off the breast and introduced him onto formula milk. Fortunately, he did not suffer from 'nipple confusion' and gladly accepted the bottle containing formula milk.
Unfortunately, we noticed that he started to have watery poos, up to six times a day. Apart from the constant diarrhoea, he was otherwise well and happy.

As my husband was lactose intolerant, we surmised that maybe our 6 month old had inherited the same trait. We switched him over to soy formula, and the watery poos stopped. He also went back to having 1 soiled nappy a day.

Our son, who is currently 2, continues to drink lactose free milk instead of cow’s milk, and absolutely loves it.

We also find that if he is exposed to small amounts of cows milk in his diet, e.g. in biscuits, cake, normal yoghurt, or cheese, this small exposure does not cause him any concerns. His lactose intolerance does not impact his lifestyle greatly.

On the other hand, at 15 months we discovered that he was allergic to peanuts. Exposure to a tiny amount of peanut butter on his toast led to lip swelling (angioedema) and a widespread rash over his body.

Severe peanut allergy was confirmed on skin prick testing with the allergy specialist. Hence our son has peanut allergy and lactose intolerance.

Food allergy vs. food intolerance. Most people ask, what is the difference? 

Food allergy is an immune response. An over-reaction of the body’s immune system to a specific part of a food, usually a protein, an otherwise harmless substance, as if it were toxic. The reaction can range from mild to life threatening (anaphylaxis).

Food intolerance is not an immune response. In some individuals, a component of food (be it protein, carbohydrate, fat or nutrients) will trigger unpleasant symptoms.


It may increase the frequency and severity of migraine headaches, skin rashes, or the stomach upset of irritable bowel.

Most reactions to food are actually food intolerance. Only 1/20 children and 1/100 adults have food allergies.

Symptoms of food allergy tend to develop very soon after consuming the food. Common triggers include eggs, cow’s milk, peanuts and tree nuts.

Common food allergy symptoms include:

  • Itching, burning, swelling around the mouth
  • Skin rash / eczema                    
  • Hives / welts
  • Diarrhoea, abdominal cramps, nausea, vomiting
  • Breathing difficulties including wheezing and asthma

Anaphylaxis is a life threatening allergic reaction. It is a medical emergency. Peanuts, insect stings and some medicines (e.g. antibiotics) are common allergens that cause anaphylaxis.

Symptoms include:

  • Difficulty breathing
  • Tongue swelling
  • Swelling / tightness of throat
  • Difficulties talking
  • Wheeze or cough
  • Loss of consciousness, collapse
  • Pale and floppy (young children)

People who have had a serious reaction to food should have an EpiPen, an emergency device which injects a dose of adrenaline into the muscle just under the skin. Adrenaline reverses the severe allergic reaction and can be lifesaving.

If you have an EpiPen, it is very important that you understand how to use it and that you have a written Anaphylaxis Action plan provided by your general practitioner or specialist.

Do allergies run in the family? 

Food allergy does not run in the family. Most of the time, children with food allergy do not have parents with food allergy.

However, if one child has food allergy, their brother / sister are at slightly higher risk of having food allergy as well, but the risk is still low.

Most people do grow out of their food allergies by the time they are 5-6 years old, especially those who are allergic to cow’s milk, soy, wheat or eggs.

In contrast, allergic reaction to peanuts, tree nuts, seeds and seafood persist in 80% of those affected. Hence only 20% grow out of these allergies, while 20% actually develop worsening allergy symptoms. 

When food allergy develops for the first time in adults, it tends to be more severe, and usually persists. For further information on allergy, asthma or immune diseases, visit – the website of ASCIA (Australasian Society of Clinical Immunology and Allergy).

Visit your GP if you still have concerns. I found the above website and talking to friends with children with similar food allergy extremely helpful.

With our son, we are vigilant about making sure that everything he eats is peanut-free.

We have two EpiPens. One is kept at home and we take it with us when we are out. The other EpiPen is kept at daycare. We made a copy of our son' Anaphylaxis Action Plan and the copy is pinned up on his daycare centre's kitchen cupboard.

We also request when dining at friends' homes, that peanuts be omitted from the menu. Everyone has been more than happy to oblige.

Our two year old has been taught to say "no" to peanuts "because it makes me feel sick", and so far, appears content to not eat anything containing nuts, and will eat everything else instead!

Discuss this issue with other parents in our Food Allergy & Intolerance Support forum.