What causes persistent itching?

Persistent itching may be caused by dry skin, irritation, allergy, medicines, infection, organ problems, or an underlying blood or immune condition. Hodgkin lymphoma, cutaneous T-cell lymphoma, and polycythaemia vera can present with itching, but itching alone does not identify cancer.

Itching may affect one area or occur across the body, with or without a rash. The pattern, skin changes, new products, medicines, travel, household contacts, and symptoms such as fever, night sweats, yellowing skin, tiredness, or weight change can guide assessment. Graft-Versus-Host Disease is another possible cause in people who have had a stem cell or bone marrow transplant and may also cause rash, dryness, or other organ symptoms. A clinician may examine the skin and request blood tests when itching is widespread or unexplained.

Arrange a review if itching lasts, disturbs sleep, spreads, or has no clear skin trigger. Use fragrance-free moisturiser, lukewarm water, gentle cleansers, and loose clothing while waiting; try not to scratch, as broken skin can become infected. Keep a note of new medicines, products, foods, travel, rash photographs, and related symptoms. Do not stop prescribed treatment without advice. People receiving cancer treatment or transplant care should contact their team before using a new cream or medicine.

Get urgent help for itching with facial or throat swelling, breathing difficulty, widespread blistering, rapidly peeling skin, or a severe new rash with fever. Contact your clinical team promptly if itching follows a transplant, comes with yellow skin, or is accompanied by signs of infection such as spreading redness, warmth, pus, or fever.

Could a medicine, skin condition, allergy, or internal problem explain this? Do I need blood tests? Which treatments are safe with my current medicines, cancer care, or transplant history?