Skin abscess, boils and folliculitis

abscess · boil · furuncle · carbuncle · folliculitis · pus collection

If there is pus, it needs draining - antibiotics alone do not treat a collection.

DISCHARGEBand C

Red flags

Facial abscess in the danger triangle around the nose and upper lip - risk of intracranial spread
Perianal, perineal or scrotal infection - consider Fournier gangrene, which is a surgical emergency
Systemic sepsis, or surrounding spreading cellulitis
Immunosuppression, diabetes, or injecting drug use - lower threshold for imaging, admission and surgical involvement
An abscess over a joint, a prosthesis or the hand - specialist territory, not an ED bedside incision

Recognise

On light skin

Tender red fluctuant swelling, sometimes pointing with visible yellow pus; folliculitis shows small red papules and pustules centred on hair follicles.

On brown and black skin

The surrounding erythema is often invisible, so an abscess may present simply as a tender, warm, firm or fluctuant lump with darker or unchanged overlying skin. Fluctuance, tenderness and warmth are the tone-independent findings - palpate rather than inspect, and consider bedside ultrasound where available, which is unaffected by skin tone: pooled across 14 studies and 2,656 patients, point-of-care ultrasound was 94.6% sensitive and 85.4% specific for a skin or soft-tissue abscess, and changed management correctly in 10.3% of cases against incorrectly in 0.7%. That is a reason to reach for the probe, not a claim that it beats examination - the meta-analysis did not test it head to head. Two other points matter here specifically: pseudofolliculitis barbae (razor bumps from ingrowing curly hair) is common in people with Afro-textured hair and is frequently misdiagnosed and treated as bacterial folliculitis, and keloid and hypertrophic scarring after incision is substantially more likely in brown and black skin - a 2026 network meta-analysis of 31,964 keloids put the pooled odds ratio at 6.14 (95% CI 3.75 to 10.07) in Black compared with White individuals, and 3.70 (2.16 to 6.34) in Asian individuals. That should inform where and how you cut and what you tell the patient. Keloids may be skin-coloured or darker than the surrounding skin, raised, firm and hairless, and cluster on the earlobes, cheeks and upper chest - so warn about those sites specifically.

In any skin tone

Fluctuance means pus, and pus needs drainage - antibiotics alone will not resolve a collection
Localised, tender, warm swelling that may point
Folliculitis: small pustules centred on follicles, usually superficial and self-limiting
Carbuncle: several adjacent follicles involved with multiple draining points, and the patient is often systemically unwell
Recurrent boils - consider staphylococcal carriage, diabetes, or hidradenitis suppurativa rather than repeated courses of antibiotics

Distribution

Anywhere with hair follicles. Boils favour the neck, face, axillae and buttocks; carbuncles the back of the neck. Folliculitis follows the distribution of follicles, often the thighs, buttocks and beard area.

Photographs

An abscess on the upper arm. There is almost no visible redness. What identifies it is the contour and the surface: a raised, rounded swelli — An abscess on the upper arm. **There is almost no visible redness.** What identifies it is the contour and the surface: a raised, rounded swelling with skin stretched tight and shiny over it. On brown and black skin, look across the limb from the side and compare it with the other side, rather than looking for erythema that may never appear.
Fitzpatrick IV (Fitzpatrick type estimated from the photograph, not stated by the source) · Oladokun RE, Lehloenya RJ, Hlela C, Ubesie AC, Katibi SO, Malande OO, Eley BS · Atlas of Paediatric HIV Infection, UCT Libraries Press 2018 - Chapter 1: Bacterial Infections, p10 · CC BY 4.0

Provenance for every photograph in this library: image licences. How much of the corpus still has no darker-skin photograph: skin tone coverage.

Mimics

Hidradenitis suppurativa — Recurrent 'boils' in the axillae, groin or under the breasts are usually hidradenitis, and repeated incision makes it worse
Necrotising fasciitis and necrotising soft tissue infection — Disproportionate pain with a soft tissue focus, especially perineal, is a surgical emergency
Cellulitis — Cellulitis without a collection does not need drainage - ultrasound distinguishes them better than examination

What to do in the ED

Decide whether there is a drainable collection - examine for fluctuance and use bedside ultrasound where available
Incise and drain adequately under good analgesia; drainage is the treatment and antibiotics are adjunctive
Take a pus swab at drainage - this is how local resistance patterns and MRSA are picked up
Antibiotics are not required for every simple drained abscess; follow NICE and local policy, and treat where there is surrounding cellulitis, systemic upset, or significant comorbidity
Do not incise on the face in the danger triangle, over the hand, over a joint or prosthesis, or in the perineum without senior or specialist involvement
For recurrent boils, look for the cause - decolonisation, diabetes screening, or a hidradenitis diagnosis - rather than repeating antibiotics
Warn about keloid and hypertrophic scarring risk where relevant, and plan the incision accordingly

Disposition

DISCHARGE

Drain and discharge with wound care advice for a simple abscess in a well patient. Refer for surgical management where the site is high-risk, the patient is septic or immunosuppressed, or the collection is deep.

Safety-netting

Return if the pain or swelling increases after drainage, if redness or swelling spreads, if you develop a fever or feel unwell, if the wound stops draining and the lump comes back, or if the area becomes hard and painful again. Keep the dressing clean and dry and attend any packing change as arranged.

Local variation

Whether the ED drains abscesses or refers to surgery, and whether packing is used, varies by site.

Sources

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