Blisters on the thumb are considered to be eczema or fungal disease of the hand. You should go to the hospital for fungal testing, which means taking some skin flakes and putting them under a microscope to see if there are mycelium. If mycelium is found, hand fungus can be diagnosed and antifungal treatment can be given, such as topical clotrimazole cream or terbinafine hydrochloride cream, etc. Oral antifungal medication can be taken if necessary. If the fungal test is negative, eczema can be considered, and topical hormonal creams such as fluticasone propionate cream or dextran cream can be used, but the specific diagnosis and treatment should be carried out under the guidance of a clinician.