A boil (furuncle) is a deep infection of a hair follicle, almost always caused by Staphylococcus aureus. It presents as a painful, red, swollen lump that gradually develops a central point of pus. Boils are common — most adults will experience at least one — and the majority can be managed with pharmacy advice and self-care. However, certain presentations require GP referral, and pharmacists are well placed to make that distinction.

How boils develop

According to NICE CKS, boils develop when S. aureus infects a hair follicle, usually through a minor break in the skin. Risk factors include friction from tight clothing, shaving, pre-existing skin conditions (eczema, acne), diabetes, obesity and immunosuppression.

The infection starts as a hard, tender, red nodule around a hair follicle. Over 3–7 days it softens as pus accumulates, eventually forming a visible white or yellow "head." Most boils will spontaneously rupture and drain, after which healing is usually rapid.

A carbuncle is a cluster of interconnected boils forming a larger, deeper infection — these always require GP assessment.

Pharmacy management

First-line: warm compresses

The most effective self-care measure is applying a warm, moist compress to the boil for 20 minutes, three to four times daily. According to NICE CKS, this promotes circulation to the area, helps the boil come to a head and encourages spontaneous drainage.

Advise patients to use a clean flannel soaked in warm (not scalding) water, applied with gentle pressure. A fresh flannel should be used each time to prevent spreading infection.

Magnesium sulfate paste BP

Magnesium sulfate paste (also known as "drawing ointment") is a traditional pharmacy product applied under a dressing to draw pus to the surface. While evidence for its efficacy is limited, it remains widely used and recommended by pharmacy teams. Apply a generous layer over the boil, cover with a clean dressing and replace twice daily.

Antiseptic skin washes

Chlorhexidine 4% skin wash (e.g. Hibiscrub) used on the affected area and surrounding skin can reduce S. aureus colonisation and help prevent recurrence. This is particularly useful for patients with recurrent boils, where nasal or skin carriage of S. aureus is often the underlying cause.

Pain management

Paracetamol or ibuprofen at standard OTC doses are appropriate for managing the pain of boils. Ibuprofen's anti-inflammatory properties may provide additional benefit.

What NOT to do

Never squeeze or lance a boil at home. Premature squeezing can push the infection deeper into surrounding tissue, cause cellulitis, or force bacteria into the bloodstream. Boils on the face carry a particular risk — the venous drainage of the central face connects to the cavernous sinus, and manipulation of facial boils has, in rare cases, led to serious intracranial infection. This is the most important counselling point a pharmacist can make.

When to refer to a GP

Pharmacists should refer patients in the following situations:

• Facial boils — particularly in the "danger triangle" (nose to corners of the mouth). These should always be assessed by a GP due to the risk of cavernous sinus thrombosis.
• Boils larger than 5cm — may require incision and drainage under sterile conditions.
• Multiple boils or a carbuncle — clusters of boils suggest deeper tissue involvement and may need oral antibiotics.
• Surrounding cellulitis — spreading redness, warmth and swelling beyond the boil itself indicates the infection is extending into surrounding soft tissue.
• Systemic symptoms — fever, malaise or feeling generally unwell suggest bloodstream involvement.
• Immunocompromised patients — including those with diabetes, HIV or on immunosuppressive medication. Lower the threshold for referral.
• Recurrent boils — three or more boils within 12 months may indicate chronic S. aureus carriage requiring decolonisation treatment (nasal mupirocin + chlorhexidine body wash, available on prescription).
• No improvement after 7 days of self-care.

Preventing recurrence

For patients with occasional boils, general hygiene measures reduce risk:

• Wash hands frequently and avoid touching the face
• Do not share towels, razors or flannels
• Change and wash bedding regularly at 60°C
• Shower rather than bathe (baths can spread bacteria to other follicles)
• Wear loose-fitting clothing to reduce friction
• Manage underlying conditions — optimising blood glucose control in diabetes is particularly important

For recurrent boils (three or more in 12 months), NICE CKS recommends GP-supervised decolonisation: nasal mupirocin 2% ointment three times daily for 5 days, combined with chlorhexidine 4% body wash daily for 5 days, along with washing all towels, bedding and clothing on the first and last day of treatment.

Finding pharmacy advice

Community pharmacists can assess skin infections and recommend appropriate self-care. Use PharmSee's pharmacy finder to locate a pharmacy near you, or explore pharmacy career opportunities.

Sources: NICE CKS Boils, Carbuncles and Staphylococcal Carriage, NHS Boils, BNF.