A skin rash that most commonly affects young adults. It may begin as a single red, scaly patch (herald patch). After this, small pink spots spread across the chest and abdomen, and may involve the uppers arms and upper legs or neck.The rash can be itchy.The rash can be itchy. It usually lasts 6 to 8 weeks, but it can last as short as 3 weeks and occasionally longer than 2 months.