boil or furunclefyo͝or´ŭngkəl [key], tender, painful inflammatory nodule in the skin, which becomes pustular but with a hard center (see abscess). It may be caused by any of various microbes, the most usual being Staphylococcus aureus. If proper care and precautions are not taken it may spread to many sites (a condition called furunculosis). Several adjoining furuncles that coalesce are known as a carbuncle. The point of entry is usually a hair follicle or a sebaceous gland duct. Boils may occur anywhere in the skin but are most common at places where the skin is constantly exposed or chafed—neck, face, ear, armpit, breast, and extremities. The treatment of small boils consists of scrupulous cleanliness, protection from irritation, and applications of antibiotic ointments and moist heat. Large boils, especially those on the nose, upper lip, or near the eyes (where there is the greatest danger of their causing meningitis or blood poisoning), must be treated professionally with antibiotics. Such lesions should be incised and drained by a physician rather than allowed to discharge spontaneously.

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