The most common food allergy in adults and children is an allergy to peanuts and tree nuts (such as walnuts, hazelnuts, almonds, cashews, pecans, macadamias, brazils and pistachios).
The most widely documented nut allergy is to peanuts with around 1 in 50 young infants thought to be affected. Peanuts are not actually a true nut; they are a ‘legume’ (a member of the bean family) and grow from the ground hence sometimes may be referred to as ‘ground nuts’. However the proteins in peanuts are similar in structure to those in tree nuts and therefore people who are allergic to peanuts can also be allergic to tree nuts. It is important therefore to avoid all nuts if you have a nut allergy.
A nut allergy can develop at any age although it is most predominantly found in children. Current NHS advice is to avoid any products containing peanuts until your child is over 6 months old. However it is worth remembering that your child may be at greater risk of a nut allergy if they have already experienced symptoms of another allergy (eczema, another food allergy).
Reactions to nuts will vary from mild to severe and can sometimes be life threatening. Many people will react after contact with small amounts (less than one nut) and some people may react to trace amounts. In these instances a nut doesn’t even need to be eaten; a reaction can be caused by just having a tiny amount on the lips or by standing next to someone eating nuts. Symptoms will usually start quickly with some people reacting within minutes.
A mild reaction will generally consist of one or more of the following symptoms:
- Tingling mouth and lips
- Face swelling
- Feeling sick, vomiting and diarrhoea
- Hives (a raised itchy rash)
- Abdomen pains
- Wheezing and shortness of breath
A severe reaction can lead to an anaphylactic shock. This is a medical emergency and help should be sought immediately from a qualified medical professional. Symptoms of anaphylaxis include; itchy skin, swollen hands, feet and face, feeling faint, collapse and unconsciousness. It is therefore important for those people who are likely to have a severe reaction to carry an injection of adrenaline (such as an EpiPen or Anapen) around with them.
A nut allergy will be diagnosed by your doctor or health professional who can carry out one of the following tests:
Skin Prick Test - a small drop of nut extract solution is placed on your forearm. A needle prick is then made through the drop. A positive reaction, showing an allergy, will occur within 20-30 minutes with the skin under the solution becoming red and itchy. A white, raised swelling (a weal) will then appear surrounding the red central area. It will take 15-20 minutes to reach full size and then fades over the following few hours. It is important that no antihistamines are taken prior to the test since this is likely to affect the allergic response during the test.
Blood test - a blood test will measure the amount of IgE (an antibody) which is produced as a result of an allergic reaction.
Food Challenge - if the above tests are inconclusive it may be necessary to take part in a food challenge test. Food will be consumed which may or may not contain nuts. Observation will be given over the following 15-30 minutes to see if there is any reaction. It is extremely important that the food challenge is conducted in a hospital where medical professionals can monitor closely in case of any severe reactions.
There is no treatment for a nut allergy apart from avoiding peanuts and tree nuts. This means not eating nuts and also ensuring that any food consumed does not contain nuts as an ingredient or is prepared in an environment where nuts may be able to contaminate foods. It is important to check all food labels for phrases, such as:
- May contain nuts
- Produced on shared equipment with nuts or peanuts
- Produced in a facility that also processes nuts
If you suspect a nut allergy you must speak with your doctor and if this is confirmed, notification of the allergy should be made to schools, family and friends. If the allergy to nuts is severe it may be advisable to wear a medical alert band. A range of different bands are available and some companies who can supply them can be found in our allergy directory here.
Sources used in the writing of this article are available on request.
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Information written by the talkhealth team
Next review: 30 July 2022