What's the difference between food allergy and food intolerance?

I came across an article recently that attempted to explain the difference between food allergy and food intolerance. I've summarised it here in case its of any use to someone.

Food Allergy (IgE mediated type)

It can be rapid and start within a few minutes or up to 2 hours after eating the allergic food.

The reaction is caused by IgE antibodies in the immune system, reacting to a small amount of the food. There is a histamine reaction that then causes symptoms including anaphylactic reactions.

Some children will grow out of their food allergy e.g milk allergies often resolve - but some allergies e.g nuts or fish, may be life-long.

Anaphylactic reactions are life-threatening and you must seek medical help immediately.

Food Intolerance

The reaction can be rapid (after a few hours) or may be slow - sometimes even days later.

A food intolerance means the body cannot tolereate a particular food and may be caused by a number of things such as the body can't produce the enzyme needed to digest it.

Some treatments can help depending on the cause and type of intolerance. Sometimes children grow out of food intolerances but some may be life-long.

In our experience, the symptoms of food intolerance are varied and can be very unpleasant for a child e.g pain, diarrhoea, vomiting so it's important to seek medical advice. We also found we were often told to remove a food for a few days to see if symptoms ease but our consultant at Great Ormond Street told us that you need to remove a food for longer than just a few days to be sure as you need to give the body time to get rid of all symptoms before you can be sure. Always seek medical advice as you may need the support of a dietician if you want to trial removing food from a childs diet - especially if they are young.