Medically reviewed by Dr. A.M. van Coevorden, dermatologist
Boil (furuncle)Painful, but usually harmless.
A boil is a painful infection of a hair follicle deep in the skin, caused by a bacterium. Doctors call it a furuncle. Over a few days the lump grows and becomes more painful, develops a yellow head of pus and usually bursts open by itself within a week. After that, the skin almost always heals without treatment.
What is a boil?
A boil starts as a red, painful spot around a hair follicle. The area swells and a yellow head of pus forms at the centre. Boils can appear anywhere hair grows, but are most common in the armpits, groin, buttocks, neck and face. When several boils cluster together, this is called a carbuncle. When boils keep coming back, doctors speak of furunculosis.
How does a boil develop?
The cause is almost always the bacterium Staphylococcus aureus, which can live on the skin naturally. Through a small wound or an irritated hair follicle, the bacterium enters the deeper skin. Irritated skin raises the risk: friction from tight clothing, heavy sweating and being overweight all play a part. Boils also develop more easily with diabetes or a weakened immune system. Some people carry the bacterium, for instance in the nose, and get boils more often as a result.
What can you do yourself?
Leave the boil alone: don't touch it and don't put anything on it. A warm compress, such as a clean cloth soaked in warm water, speeds up ripening and eases the pain. Has the boil burst? Cover it with a sterile dressing and wash your hands well, so the bacteria don't spread through towels or bedding.
Please note
Don't squeeze. Squeezing can make the boil burst inwards, spreading the infection and making it worse.
When to see a dermatologist or doctor?
Most boils heal by themselves. Do contact a doctor with fever, feeling unwell, rapidly spreading redness or a carbuncle; a course of antibiotics or a small incision to drain the pus is sometimes needed. Getting boils more than twice a year? A doctor can test whether you carry the bacterium; a prescription nasal ointment can then help prevent new boils. Unsure about a spot, or does it keep returning? A dermatologist can assess your skin and tell you exactly where you stand.
Please note
Is the boil on your face, especially around the nose or upper lip? Always have it assessed: there the infection can spread inwards.
Frequently asked questions about boils
Can you squeeze a boil?
No. Squeezing can make the boil burst inwards, spreading the infection and making it worse. Let it ripen until it opens by itself; a warm compress speeds that up.
How long does a boil last?
A boil usually bursts open by itself within a week and then heals. If it doesn't open, it generally still clears within a few weeks. If it lasts longer or gets worse, have it assessed.
When should you see a doctor about a boil?
With a boil on the face (especially around the nose and upper lip), with fever or feeling unwell, with rapidly spreading redness, with a carbuncle, and with diabetes or a weakened immune system. A course of antibiotics or a small incision is sometimes needed.
Why do boils keep coming back?
Often because someone carries the bacterium without knowing, for instance in the nose. With more than two boils a year, a doctor can test for this with a swab; a prescription nasal ointment can help prevent new boils.
Is a boil contagious?
The boil itself isn't, but the bacteria in the pus can spread via hands, towels and bedding. Good hygiene after it bursts prevents new infections in yourself and others.
Sources and more information
- Steenpuist (furunkel) en negenoog (karbunkel) (huidziekten.nl)
- Ik heb een steenpuist (thuisarts.nl)