In short
A boil is an infected hair follicle; a cluster is a carbuncle; a larger pocket of pus is an abscess. Most boils drain and heal within two weeks with warm compresses, squeezing spreads the infection, and repeated boils are worth checking for diabetes.
Emergency if: Rapidly spreading redness, red streaks from the boil, high fever with feeling very unwell, or confusion — go to an emergency department now.
On your report
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On this page
01
Boil, carbuncle, abscess
A boil is a deep infection of a hair follicle: a hard, painful lump that fills with pus. When several boils form together with more than one head, it is called a carbuncle. A skin abscess is a larger collection of pus in a cavity under the skin — usually round, painful and warm, with a middle that may feel soft.
Boils range from the size of a pea to that of a golf ball and are most common on the face, neck, armpits, buttocks and thighs. Carbuncles favour the back and the nape of the neck and are more common in men, particularly in middle age.
02
Why they happen
Most boils are caused by Staphylococcus aureus, a bacterium that many healthy people carry harmlessly on their skin and in their nose — an estimated ten to twenty per cent of people carry it. A small nick, graze or friction lets the bacteria into the wall of a hair follicle, which is a weak point in the skin's defences.
Most people who get boils are otherwise healthy and have good hygiene. The risk is higher with diabetes or any condition or medicine that weakens the immune system, including steroids, with eczema, with obesity or malnutrition, in smokers, and after close contact with someone who has boils.
03
What to do, and what not to
Most boils go away on their own, but they need to open and drain to heal, and this usually happens within two weeks. Soak a clean cloth in warm water and hold it against the boil for about ten minutes, around four times a day; this speeds the boil coming to a head and draining. Once it drains, keep it covered with a clean dressing and wash your hands afterwards.
Never squeeze, pick, pierce or try to cut a boil open at home. It pushes the infection deeper and wider and makes it worse. Antibacterial soaps and creams do little once a boil has formed. Do not share towels, and avoid swimming pools and the gym until it has healed, because the bacteria spread to others.
04
Drainage and antibiotics
Deep or large boils, carbuncles and abscesses often need to be drained by a doctor. This is a small procedure under local anaesthetic, in which a cut lets the pus out, and for a true abscess it is the main treatment rather than an optional extra.
Antibiotics are added when the infection is severe, when it is spreading into the surrounding skin, when boils keep coming back, or when the immune system is weakened. A swab may be taken to identify the bacteria, particularly if boils are not clearing, to check for antibiotic-resistant strains.
05
Boils that keep coming back
Repeated boils are worth investigating rather than treating one at a time. A doctor will usually check for diabetes, anaemia and iron deficiency, and consider immune problems. Recurrences often come from bacteria carried in the nose, armpits or groin, which can be cleared with an antiseptic body wash and a nasal ointment.
Practical steps reduce recurrence: wash towels and bedding at least weekly on a hot wash, do not share towels or flannels, keep nails short and avoid picking the nose, lose weight if boils form in skin folds, and stop smoking.
06
When to get help
See a doctor if a boil has not improved after two weeks of home care, if you keep getting boils, or if you have a carbuncle. Seek urgent advice if a boil is on your face — particularly the middle of the face — or over the spine, if the skin around it becomes hot, painful and swollen, if redness is spreading away from it, if you feel hot, cold or shivery, or if you have diabetes or a weakened immune system.
Go to an emergency department for a rapidly spreading red area, red streaks running from the boil, a high fever with feeling very unwell, or confusion — these suggest infection spreading into the blood or deeper tissues.
When to act
Routine — see a doctor
A single small boil in a healthy person: warm compresses four times a day, no squeezing, and expect it to drain and heal within about two weeks.
Same-day — call promptly
A boil on the face or over the spine, a carbuncle, spreading redness, feeling shivery, a boil not improving after two weeks, or any boil with diabetes or a weakened immune system.
Emergency — act now
Rapidly spreading redness, red streaks from the boil, high fever with feeling very unwell, or confusion — go to an emergency department now.
Values mentioned in this story
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Sources
- Boils — NHSnhs.uk
- Skin Abscess — NHSnhs.uk
- Boil (Furunculosis) — DermNetdermnetnz.org
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