Introduction:
Allergy affects approximately one-third of the world’s population, and the rates are growing. In Europe, it has been noticed that the risk of asthma and allergy is lower in the rural as opposed to urban population. There is a tendency for several allergic diseases to be present in the same person at the same time.

Objective:
The aim of the study was to verify the co-occurrence of allergic multimorbidity and food allergy and intolerance in a group of children.

Material and methods:
The multicentre cross-sectional study enrolled 1,008 children and adolescence aged 6–18 years (51.2% boys, 48.8% girls). The study comprised a questionnaire (respondents’ declarations) and an outpatient examination (diagnostic examination followed by a medical diagnosis). The study was conducted as part of the 2016–2020 National Health Programme.

Results:
In the study group, allergic rhinitis (AR) was present in 46.4%, bronchial asthma (BA) in 11.2% and atopic dermatitis (AD) in 6%. Allergic multimorbidity (simultaneous presence of 2 or more of the allergic diseases AR, BA and AD) was diagnosed in 9.7%. A single allergic disease (of the 3) was diagnosed in 43.4%. A diagnosis of food allergy and food intolerance was reported respectively at 29.6% and 14.3% participants with doctor-diagnosed allergic multimorbidity. Among those without any of the 3 allergic diseases, the percentage were 14.4% and 9.1%, respectively.

Conclusions:
Food allergy or food intolerance was more common in subjects with allergic multimorbidity than in subjects diagnosed with one allergic disease or those free of allergic diseases.