This article is focused mainly on the influence of food additives such as natural and artificial food colouring, conservative agents, antioxidants, flavour enhancer, sweeteners and unintentional trace contaminants present in food, such as nickel and chromium, which cause serious disorders of a human organism. Food additives may induce an adverse reaction of atopic patients and provoke clinical symptoms including first of all dermatitis, rhinitis and asthma, urticaria, angioneurotic edema, and contact urticaria. Systemic and respiratory reactions to food colorants and benzoates have been claimed to occur more frequently in acetylsalicylic acid-sensitive patients than in the non-reactors. Hypersensitivity reactions in organs other than the skin and respiratory tract are rare or poorly documented. The literature data indicate that food additives are suspected to stimulate hyperactivity and psychoneurotic reactions too.