Itchy skin rashes happen for a variety of reasons, manifesting as a physical irritation. Because their appearance and severity varies, sometimes it is important to pay careful attention to other symptoms that accompany it.
Know your family's medical history. It is possible that other members have experienced frequent or recurrent skin rashes. If there are others with the same problem in the family, you may suffer from eczema. People who have asthma or hay fever are more likely to suffer from eczema. Other symptoms of eczema include redness, scaly skin that becomes crusty after scratching, small blisters and infections.
Look at the appearance of the rash. Itchy skin rashes that are circular with small bumps within the circle may be due to granuloma annulare (a chronic condition associated with thyroid problems) or ringworm infection. Both are likely to appear on hands and arms before spreading to other body parts.
Pay attention to the size of the rash. A large itchy rash that is almost perfectly circular and appears on the chest or back (before spreading) indicates the possibility of suffering from pityriasis rosea, a condition caused by a non-contagious virus.
Analyze your activities during the last 24 to 48 hours. A rash that is accompanied by a burning sensation may indicate exposure to sun, a chemical irritant or an allergy to a new food or medicine. If you have engaged in activities that may be related to those symptoms, you should examine those possibilities first.
Look at the spread of the rash. A rash that seems to appear and disappear on different parts of the body with no other symptoms except itchiness may indicate a viral rash. These usually go away on their own after a few days and require no other treatment than a cream to relieve itchiness.