The common causes of itchy blisters in the cracks of the fingers are ringworm, hand eczema, sweat herpes and so on. 1. Ringworm: ringworm is caused by fungal infection of the skin on the hands, which can lead to small blisters, flaking and itching on the patient’s fingers. 2. Hand eczema: hand eczema is an allergic inflammatory reaction of the skin of the hand, often in the fingers, itching, erythema, papules, blisters, flaking and other clinical manifestations. 3. Sweat herpes: Sweat herpes often occurs in the palms of the hands, fingers, soles, toes and other parts of the clinical manifestations of sweaty hands and feet, blisters, peeling and so on, accompanied by varying degrees of itching and burning sensation. There may also be other causes, it is recommended that patients go to the hospital in a timely manner, to clarify the cause of the disease after treatment. The application of drugs need to strictly follow the doctor’s instructions, if there is any discomfort can stop the drug to see a doctor.