Itchy skin that isn't accompanied by other obvious skin changes, such as a rash, is most often caused by dry skin (xerosis). Dry skin usually results from environmental factors that you can wholly or partially control. These include hot or cold weather with low humidity levels, long-term use of air conditioning or central heating, and washing or bathing too much.
Other possible causes
Other conditions cause itchy skin as well. Skin disorders, internal diseases, allergies and drug reactions top the list.
• Skin conditions and rashes. Many skin conditions cause itchy skin, including psoriasis, inflammation of the skin (dermatitis), scabies, lice, chickenpox, hives and dermatographism. In these cases, the itching usually affects specific areas and is accompanied by other signs, such as red, irritated skin or bumps and blisters.
• Internal diseases. These include liver disease, malabsorption of wheat (celiac disease), kidney failure, iron deficiency anemia, thyroid problems and cancers, including leukemia and lymphoma. In these cases, the itching usually affects the whole body, rather than one specific area. The skin may look otherwise normal except for the scratched areas.
• Irritation and allergic reactions. Wool, chemicals, soaps and other substances can irritate the skin and cause itching. Sometimes the substance causes an allergic reaction, such as in the case of poison ivy or cosmetics. Food allergies also may cause itchy skin reactions.
• Drugs. Reactions to drugs, such as antibiotics, antifungal drugs or narcotic pain medications, can cause widespread rashes and itching.
• Pregnancy. Some women experience itchy skin during pregnancy, especially on the abdomen, thighs, breasts and arms. Also, itchy skin conditions, such as dermatitis, can worsen during pregnancy.