Itchy left back may be caused by prickly heat, atopic dermatitis, eczema, etc. and should be analyzed according to the situation. 1. Prickly heat: If you wear too many clothes, in summer or in a hot and humid environment, which causes small blisters, pimples and other dermatological diseases on the skin of your left back, you will show the symptom of itchy left back discomfort. 2. Allergic dermatitis: If the left back is exposed to suspected allergens, causing local skin erythema, pimples, blisters and other uncomfortable symptoms, it can show the phenomenon of itchy left back discomfort. 3. Eczema: due to a variety of factors causing the skin to appear chronic, inflammatory, itchy skin disease, when the left back with eczema symptoms, manifested in the left back uncomfortable itchy phenomenon. Caused by the left back uncomfortable itchy cause more, need to go to the hospital in time to confirm the examination, clear cause for targeted treatment.