The aged population is increasing worldwide, and it is therefore essential to identify the specific features of diseases in aged groups. The diagnosis of allergic diseases in the elderly is more difficult than in younger patients, because the differential diagnosis of other diseases must be excluded. The treatment of elderly allergic diseases is also challenging because most elderly patients have co-morbidities that affect the disease outcome. Co-morbidity is one of the most important factors to be considered when elderly allergic patients are treated. Co-morbidity and medications for co-morbidity affect allergic disease treatment in terms of drug-drug interaction, medication adherence, adverse drug reactions, and so on. Many studies of allergic diseases are focused on the younger population, while few studies have dealt with elderly allergic diseases. Further studies including diagnosis and treatment guidelines for elderly allergic disease are needed.