Z91: Personal history of risk-factors, not elsewhere classified

Z91.0: Personal history of allergy, other than to drugs and biological substances

With an allergy, the immune system overreacts to certain substances. Such substances may be harmless substances in the environment, drugs or certain chemicals, for example. An allergy may be accompanied by a range of symptoms. For example, you may experience sneezing, swellings or changes to your skin. The eyes and skin may feel itchy. When allergic reactions are very severe, you may suffer from breathlessness or circulatory problems.