Food Allergy - Paediatrics

Food Allergy

·        Commonest in first years of life (gut less good at keeping allergens out)

·        5 – 6% of children cf 1 – 2 % of adults

·        Commonest allergens: milk, eggs, peanuts, soy, wheat

·        Mechanisms include:

o  IgE mediated – rapid onset, due to mast cell activation and histamine release

o  Delayed hyper-sensitivity

·        Scenarios:

o  Urticaria/angio-oedema:

§  Rapid onset after contact with oral mucosa

§  Chronic urticaria rarely due to foods (except ?food colourings)

§  Confirmed by skin testing

§  IgE mediated

§  Risk of future anaphylaxis (systemic reaction distant from contact point).

·        Risk factors for fatal outcome: Asthma, peanut/nut allergy 

·        Treatment: Adrenaline 0.01 ml/kg of 1:1000 im (10 mcg/kg) [relatively safe im, compared with iv, which risks tachycardia and arrhythmia so would only want to do it in cardiogenic shock]

·        Atopic dermatitis: takes days to weeks following food exposure. Strong association between severe asthma and food allergy (60%)

·        GI symptoms may be at any point in the gut: oesophagus (reflux), stomach (vomiting), small bowel (colic, diarrhoea, malabsorption) to large bowel (diarrhoea, gas, bloody stools, mucus, constipation)

·        Respiratory symptoms: much less common with foods. Oral allergy syndrome: pollen allergic individuals may get oral tingling/swelling after eating some fruits/vegetables