How common is nut allergy and what are the symptoms?

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How common is nut allergy and who gets it?

In the UK about one in 100 people has an allergy to peanuts and about one in 200 people has an allergy to tree nuts. The number of people with peanut allergy is growing.

Nut allergy is the most common type of severe food allergy. It often starts when children are very young. Most first allergic reactions take place when a child is between 14 months and two years old. Unlike other food allergies such as milk allergy, nut allergy is something that you are unlikely to grow out of. Only about one in five people with a nut allergy will grow out of it, and these tend to be the people who have mild reactions.

If you have what is called atopy, or if atopy runs in your family, then you are more at risk of developing an allergy to nuts. Atopy is the name for a group of allergic conditions that include hay fever, asthma and eczema. If you have an allergy to peanuts then you may also react to tree nuts.

What are the symptoms?

Allergic reactions to nuts can vary from mild to very severe, and are sometimes life-threatening. Symptoms often start very quickly, within an hour of having come into contact with a nut, and sometimes within minutes. Reactions that take place more than four hours after coming into contact with nuts are unlikely to be an allergy.

Signs and symptoms of a mild allergic reaction can include:

Your mouth and lips tingling.
Your face swelling.
Feeling sick.
Urticaria (nettle rash or hives).
Colicky pains in your abdomen (tummy or stomach).
A feeling of tightness around your throat.

Signs and symptoms of a more severe allergic reaction can include:

All of the above.
Wheezing or difficulty breathing due to an asthma-like attack, or swelling around your throat.
A sense of impending doom.
Dilation (opening up) of your blood vessels which can cause:

- general redness of your skin
- a fast heart rate
- a low blood pressure, which can cause you to feel faint or to collapse.

This severe reaction is called anaphylaxis and without quick treatment you would soon become unconscious. A small number of people die every year as a result of this kind of severe reaction, usually because they do not get treatment quickly enough. If you think you are having an anaphylactic reaction you need to call an ambulance straightaway and get immediate medical help.

About one in three people with a nut allergy have an initial reaction to the nut, followed by a second reaction between one and eight hours after the first. This is why it is important to stay in hospital after an initial reaction.