A boil (furuncle) starts as a painful pink or red bump on the skin. Over the next few days the swelling and inflammation increases and the boil fills with pus – it can be pea-sized or larger. A yellow or white tip develops and eventually the boil ruptures and drains. Small boils can heal without scarring, but larger ones can leave a scar or patch of discoloured skin. 

Common sites for boils include hair-bearing areas of the face, neck, axillae, buttocks, groin, and the anogenital region.

Carbuncles are clusters of boils that appear as tender, multiple abscesses discharging pus from several points and inflammation of surrounding tissue. The patient may have a fever and feel systemically unwell. Common sites for carbuncles include the back of the neck, shoulders, hips and thighs. There is also a risk of secondary infection, such as cellulitis. 

Management

The management of boils, carbuncles, staphylococcal paronychia and whitlows depends on whether they appear to contain a large collection of pus or not. For small boils, moist heat should be applied three to four times a day alongside analgesics such as ibuprofen or paracetamol. This relieves discomfort and helps to bring the boils to a head so that they drain spontaneously. 

Spontaneously discharged lesions should be covered with a dressing to prevent spread of infection. Good personal hygiene such as hand washing, using separate towels etc., is essential to avoid spreading the infection to other areas of the body or other people. 

If the lesions contain a large amount of pus (a fluctuant mass), they may be incised and drained by a suitably experienced practitioner. Moist heat and analgesics will also be helpful. According to NICE guidelines, antibiotic treatment is only indicated if the patient has a fever, comorbidities, if the boil is on the face, or if the lesion is very large. Patients should be advised not to squeeze the lesions or attempt to incise and drain them themselves.