Welcome to HealthcareMagic. A rash
of viral origin, depends where the site is, and which type of viral it is, might stay for varied period of time.Like for example, a herpetic lesion at the mucocutaneous junction(lip) might stay for just a couple of days. If it is lasting long,l I would suggest, you consult with a dermatologist
, and get evaluated thoroughly, in case not improving. Get well soon.