We call rash the appearance of one or more red blotchy rash. The rash may be asymptomatic, but in most cases, is accompanied by other symptoms such as itching, fever or local pain.
Urticaria is an extensive skin reaction, with allergy characteristics, quite common, affecting about 20% of people at some point in life. Urticaria can occur in adults and children, and is usually triggered by infections, medications, food, heat, or other stimuli.
