Associations of excessive irritability with common illnesses and food intolerance.

In a national study of almost 7000 primary school children, parents' perceptions were used to test the hypothesis that the child's irritability was associated with food intolerance independently of other symptoms. After adjustment in a multiple regression analysis for asthma or wheeze, cough, eczema, hives, diarrhoea and vomiting, rhinitis, hay fever and headache, and the social factors of father's social class, maternal education and maternal age, a highly significant association between perception of food intolerance and irritability (P less than 0.001) remained. Though we cannot rule out that irritable children's parents could be biased towards diagnosing food intolerance the possibility that some children do have behavioural disturbance associated with reactions to food needs to be explored further, preferably with a double blind challenge assessment.