Sometimes the substance, such as poison ivy or cosmetics, causes an allergic reaction
. Food allergies also may cause skin to itch.
Drugs. Reactions to drugs, such as antibiotics, antifungal drugs or narcotic pain medications, can cause widespread rashes and itching.
Pregnancy. During pregnancy, some women experience itchy skin, especially on the abdomen and thighs. Also, itchy skin conditions, such as dermatitis, can worsen during pregnancy.