Blisters in medical terms means blisters, and blisters on the thumb can be caused by conditions such as tinea cruris, herpes sweats, and palmoplantar pustulosis. 1. Ringworm: Ringworm is caused by dermatophytosis infection, which is an infectious disease. The patient’s skin will appear dry, blisters, flaking and other symptoms, accompanied by itching. 2. Sweat herpes: the cause of sweat herpes is not clear, the disease may be related to dermatophyte infection, local infection, mental factors and other factors. Patients will have blisters on their hands or feet, which may be accompanied by burning sensation, tingling and intense itching. 3. Palmoplantar pustulosis: The etiology of palmoplantar pustulosis is unclear and may be related to genetics, stress, and localized infections. Patients may develop deep-seated pustules on the palms or soles of the feet. There are many reasons for blisters on the thumb, and it is recommended that patients go to the hospital for examination to clarify the cause of the disease and treat the symptoms.