Final answer:
Allergies are immune responses to typically harmless substances called allergens, which can cause symptoms ranging from mild to life-threatening. They are more prevalent in developed countries, affecting around 20 percent of the population with conditions like hay fever or contact dermatitis. Patient allergies are important to document to prevent allergic reactions in medical environments.
Step-by-step explanation:
Allergies are hypersensitivity disorders where the immune system reacts abnormally to a typically harmless substance, known as an allergen. Common allergens include pollen, dust mites, molds, and certain foods like peanuts, as well as insect stings and some medications such as aspirin. The symptoms of an allergy can range from mild, like sneezing and itchy eyes, to severe, such as difficulty breathing and anaphylaxis, which is a potentially life-threatening reaction.
The prevalence of allergies is notably higher in developed countries, with around 20 percent of the population affected by hay fever, 20 percent by contact dermatitis, and approximately 6 percent by food allergies. Contrarily, allergies are much less common in less affluent nations. This increase in allergies over the past few decades suggests the influence of environmental factors and lifestyle changes on the immune system.
Patient histories often include a section on patient allergies, as they are critical for preventing allergic reactions, especially in medical settings where exposures to new medications or substances can occur.