Acne can itch. So can scars. Various bacterial, fungal and viral infections also cause itching. Some itches coincide with the seasons. Hay fever, with itchiness of the eyes and nose, accompanies spring.
Summer brings jellyfish stings, mosquito bites, poison-ivy rashes, prickly heat and sunburn.
Itching of the back, chin or neck commonly precedes attacks of asthma, which often stems from allergies. Other causes of itching include aspirin, birth-control pills, the antimalarial drug chloroquine, morphine, penicillin and rabies shots. Sometimes it's not the medication itself that causes the itch, but the dyes or preservatives in the product. Often, itching is not just skin-deep. It is a symptom of many systemic diseases, including diabetes, kidney failure, liver disease, Lyme disease, nerve disorders, thyroid disease and various forms of cancer.