👉 Hylesia is a disease in which an individual experiences symptoms similar to those of an allergic reaction, such as hives or itching, but without the presence of an actual allergy. This condition can be caused by a variety of factors, including certain food items, medications, and environmental triggers. Symptoms typically last for several hours and include redness, swelling, and difficulty breathing. Treatment often includes over-the-counter antihistamines to manage symptoms.