Itching is another common skin related issue but it can be caused by many things, from dryness to skin diseases and other illnesses.Examples include dry skin (xerosis), eczema (dermatitis), psoriasis, scabies, parasites, burns, scars, insect bites and hives. Internal diseases. Itching on the whole body might be a symptom of an underlying illness, such as liver disease, kidney disease, anemia, diabetes, thyroid problems and certain cancers.