Elderly patients with certain chronic diseases, such as hypertension, diabetes and malignant tumours, are often more prone to purpura because of increased capillary fragility due to arteriosclerosis or malnutrition; collagen synthesis requires the participation of vitamin C. Vitamin C deficiency reduces the toughness of blood vessel walls and increases capillary fragility, and as we age, the body’s vitamin C content decreases progressively, a physiological change that also makes the elderly prone to purpura.