Tree nut allergy is more common in older children and adults than in infants.
Symptoms usually start straight after eating the nut. They include a rash (hives or “nettle” rash), swelling of the lips or around the eyes, and itch. Some children have an itchy throat, others feel sick or vomit.
Severe reactions are much less common but may include difficulty breathing (wheeze or throat swelling), feeling faint or dizzy. These are features of anaphylaxis and need urgent medical attention.
Most people with tree nut allergy only have mild reactions. Severe reactions affecting the breathing can occur, these are of particular concern in those with bad asthma and will need urgent medical attention.
Some nuts are from the same family and may also cause reactions (this is known as cross-reactivity). Cross-reacting nuts should be avoided. Examples include:
- cashew and pistachio nuts
- pecan and walnuts.
Children with nut allergy should never eat nuts from a mixed nut collection.
It is often easier to avoid all nuts in childhood to avoid confusion for other family members, friends, and school staff. As children grow older and become more independent, they may want to know exactly which nuts they can and cannot eat. This needs to be discussed with your allergist who may repeat allergy tests.
Chestnuts, coconut and seeds like pine nuts, sesame and sunflower seeds can usually be eaten. Your specialist can advise.
The diagnosis of tree nut allergy is based on the history of a typical reaction after contact. Positive allergy skin prick or blood IgE tests support the diagnosis. Where there is no history of a reaction to the nuts, allergy tests should be interpreted with caution, as children can have a positive allergy test but tolerate the nut without getting a reaction.
Skin prick tests are safe and can be done in clinic if antihistamines have not been taken for a few days. Blood tests are not affected by antihistamines, but the results are only available in a week or so after the clinic appointment.
If the diagnosis is uncertain an oral challenge is sometimes recommended.
Cashews, pistachios, almonds and hazelnuts can be hidden ingredients in food, particularly in Asian, Chinese and Thai food. Hazelnuts, Brazil nuts, cashews and almonds can also be found in baked sweets and chocolates. Unpackaged foods in bakeries and delicatessens sold alongside foods containing nuts may be contaminated with tree nuts and should be avoided.
You should read the ingredients list on pre-packaged foods and ask for the chef’s reassurance in restaurants. Ringing the food outlet to get information before planning a meal can avoid disappointment.
It is often easier to avoid all nuts, than avoid just some nuts.
A written management plan will be given in clinic. Allergy medication should be available at all times.
If tree nuts are accidentally eaten, get the child to spit it out if possible and give an antihistamine.
Severe symptoms are:
- Difficulty breathing (wheezing, noisy breathing, blue colour)
- Swelling in the throat (noisy breathing, drooling)
- Feeling faint or dizzy, looking very pale (lie the child down with their legs raised).
If any of these severe symptoms occur get help straight away and dial 999 stating “anaphylaxis” (ana-fil-ak-sis).
It is important to inform the nursery/school and any after school clubs. Any other carers such as grandparents, relatives and school friends’ parents will also need to know
Yes, tree nut allergy is life long and hence the avoidance will have to be life long.
There is no cure for tree nut allergy at present.