Raised, Itchy Red Rash on the Skin (Hives)
Red, itchy, raised patches may suddenly appear on the skin when a person is exposed to an allergen they’re sensitive to. This usually happens when something touches your skin and your immune system misreads it as an attack. It sends antibodies to the contact point and causes inflammation.
Hives (or urticaria) [4] is the medical term for this condition, and it can affect any part of the body. Sometimes these patches are large welts with well-defined margins. Other times, they may be small and resemble rashes.
Hives rashes are normally not a life-threatening condition. The rashes and welts can be treated at home and often disappear within a few minutes or days. You should see a doctor if the symptoms don’t get better after two days or if the rash is spreading.