Itchy blisters on the seams of toenails may be caused by blistering tinea pedis, eczema, and herpes sweating. 1. Blister tinea pedis: If you don’t pay attention to the hygiene of your feet, or wear shoes and socks that are not breathable, it may lead to fungal infections, which may cause blister tinea pedis, with clusters or scattered distribution of small blisters, which are usually accompanied by itching, tingling and other uncomfortable symptoms. 2. Eczema: If the skin of the feet is stimulated by skin care products, laundry detergents and other chemicals, it may lead to allergies and cause eczema, resulting in the appearance of pimples, erythema, blisters, vesicles and other skin damage, often accompanied by itching symptoms. 3. Sweat blisters: mostly occurring on the palms of the hands, soles of the feet, or on the sides of the fingers and toes, these areas may appear dense small blisters, often accompanied by pain or intense itching. Toenail seam long blisters, and accompanied by itching symptoms, should be timely consultation, a clear diagnosis of the cause of the disease, and then targeted treatment.