Red, swollen and ulcerated feet may be caused by diabetic foot, tinea pedis, eczema and other reasons. 1. Diabetic foot: the mechanism of diabetic foot is more complex, the two most important factors are neuropathy and ischemia. Patients with diabetic foot are combined with arterial occlusion, and there is ischemia in the distal part of the tissue, resulting in necrosis of the skin of the distal tissue. Redness, swelling and ulceration between the toes appear, and gradually spread to other parts of the body as the disease progresses. 2. Tinea pedis: when the body’s resistance is low, the local skin fungal infection destroys the tissue structure, resulting in blisters, peeling, ulceration, itching and other symptoms, causing redness, swelling and ulceration between the toes. 3. Eczema: mostly acute eczema, due to external environmental stimuli, such as sweating more, allergens stimulate the skin, caused by skin hypersensitivity. When the disease is more serious, small blisters may appear, often fused into pieces, often due to scratching to form ulcerated surface, with obvious plasma exudate. There may be other causes of redness, swelling and ulceration of the feet, when there is redness, swelling and ulceration between the toes, it is recommended to consult a doctor in time, and targeted treatment.