Will skin redness spread to other areas?

Generally speaking, redness is self-limiting, but it depends on the cause, as I mentioned again. Cellulitis, which is a form of a skin infection, can generally spread to other areas if it is not managed appropriately. So generally in practice, in hospital practice particularly, if someone presents with significant redness caused by cellulitis with other features that are concerning, for example a high temperature, abnormal observations like blood pressure, heart rate, then we generally tend to mark this area and over time if this is not treated can spread. So marking and observation is important. However with adequate treatment skin redness does tend to settle over time and will not spread to other areas.