Stress can trigger all sorts of physical reactions, including a rash, which is an area of irritated skin. Stress hives are a type of rash that takes the form of raised bumps or welts. They might be red, itchy, and so numerous that they look like one large patch of raised skin. When you’re under stress, your body releases a chemical called histamine, which may then create inflamed bumps. Scratching hives can release more histamine and worsen the condition. Instead, try using an antihistamine. A cold compress might also help you cope with the itching.