• A boil is a red, hot, tender, inflammatory nodule with walled-off purulent material, arising from a hair follicle. Boils can exude pus and necrotic material.
• A carbuncle is caused by infection of a group of adjoining hair follicles which develop into large, swollen, tender masses with multiple points draining pus. There may be inflammation in surrounding and underlying connective tissue.

• Size and position of the lesion.
• Presence of pus or fluctuance (wave-like feeling on palpating skin overlying a fluid-filled cavity with nonrigid walls).
• Symptoms suggesting systemic spread of infection.
• Whether a swab is required.

In depth

• Swabs are not routinely required for initial management.
• Swabs are indicated if the lesion is getting worse over 48 hours despite antibiotic treatment, or there is no response to empirical antibiotic treatment within 5–7 days.

In depth

• Advise the person to apply moist heat three to four times a day.
• Offer antibiotics if:
• There is also fever or cellulitis.
• The lesion is large (e.g. carbuncle) or on the face.
• There are other comorbidities (e.g. diabetes).
• Offer analgesia (paracetamol or ibuprofen) if needed.
• Consider admission if the person is unwell, or the infection is in an area where complications can be serious (e.g. the face). Clinical judgement should be used, taking into account the rapidity and degree of spread, and whether or not the person (or carer) is able to follow instructions reliably regarding monitoring of possible complications.

In depth

• Incise and drain (this can be done locally if the skills to do this exist within the practice, or alternatively refer).
• Offer antibiotics if:
• There is also fever or cellulitis.
• The lesion is large (e.g. carbuncle) or on the face.
• There are other comorbidities (e.g. diabetes).
• Offer analgesia (paracetamol or ibuprofen) if needed.
• Advise people to cover the lesion with a sterile dressing.
• Consider admission if the person is unwell, or the infection is in an area where complications can be serious (e.g. the face). Clinical judgement should be used, taking into account the rapidity and degree of spread, and whether or not the person (or carer) is able to follow instructions reliably regarding monitoring of possible complications.

In depth

• Oral flucloxacillin is recommended for empirical treatment.
• Oral erythromycin (or clarithromycin if erythromycin is not tolerated) is an alternative for people with penicillin allergy.

In depth

• A 7-day course of empirical antibiotic treatment is recommended.

In depth

• Swab the lesion to confirm the causative organism and antibiotic sensitivities.
• If staphylococcal infection is confirmed, check for carriage of Staphylococcus aureus.
• Exclude other underlying causes, for example:
• Systemic disorders (e.g. diabetes, immunocompromised) — consider full blood count and blood glucose.
• Skin disease (e.g. scabies, pediculosis, eczema).
• Localized predisposing factors (e.g. industrial exposure to chemicals, oils, poor hygiene).

In depth

• For more information on the assessment and management of staphylococcal carriage, see Scenario: Staphylococcal carriage.