Factors that cause severe allergic reactions include food, medications and insect bites, with an additional approximately 15% of factors being uncertain. Food is the most common trigger for allergies in children, while in adults it is medication. Almost any food or medication can cause an allergic reaction, with certain foods (nuts) and medications (antibiotics, NSAIDs and aspirin, inotropes) accounting for the majority. A large number of allergic cases are idiopathic. Drug and insect bite induced allergic reactions have the greatest prognostic impact in people aged 60 years and older.