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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. Vitamin A deficiency and diabetes too can cause dry skin. Hence these should be ruled out.
Drink plenty of fluids and water. Keep a trough of water or use a humidifier at home in your rooms. You can apply petroleum jelly and glycerine on your skin at bed time. When choosing a moisturizer, look for oil-based creams and ointments. Fresh juice of tomato, cucumber and orange can be applied.
If you have blisters at tip of fingers and dry skin then you need to rule out certain conditions such as diabetes, psoriasis, hypothyroidism, contact dermatitis, atopic dermatitis and malnutrition.
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.
If the itch is only in the exposed part, it can also be due to sun allergy. Pubic and body lice can be another cause. Worms are another cause of both anal and body itch and hence get a stool test.
Low estrogens are also supposed to be the cause. Try a diet rich in estrogens. Hormone replacement therapy can also help a few. PCOD and hormone imbalance too can be a cause.
Please consult your PCP for primary examination followed by proper referral. Take care!