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Dry skin is the commonest cause of generalized itching. Applying a moisturizer and using only soaps that are gentle on the skin is helpful in this case. Generalized itching can be due to allergy. Common allergens are pollen, mold, dust, pet dander, synthetic fiber, food, cosmetics (powders, soaps, shampoos—see if anything was recently changed) or drugs. You must get an allergy test done, either a skin test or RAST, to know what you are allergic to. Fungal infections like tinea corporis and tinea cruris too cause whole body itching along with genital itching. Liver problems too can cause generalized itching. Hypothyroidism too can be a cause.
If the itch is only in the exposed part, it can also be due to sun allergy. Please consult your PCP to rule out these causes. Take care!