31st January, 20204 min read

When to worry about a boil

Medical reviewer:
Healthily's medical team
Healthily's medical team
Alex Bussey
Alex Bussey
Last reviewed: 31/01/2020
Medically reviewed

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A boil is a swollen, red lump under the skin that can become pus-filled over time. It is often sore and painful, but usually clears up on its own.

Studies show that the average boil bursts after 2 to 3 days (although it can take up to a week or more), so it’s best to let the healing process happen naturally.

Knowing what to expect from a boil is key to knowing when to care for a boil yourself and when to get it checked by a doctor.

What to expect from a boil

A boil often starts as a tender or itchy spot surrounding a hair follicle. As the affected area starts to fill with pus, the boil grows and forms a firm, red lump under your skin.

Boils often look like large pimples, and most grow to be the size of a pea.

After several days or weeks, the boil will usually form a whitish head and then burst, allowing the pus to drain away. Some boils may settle slowly without bursting.

Most small to medium-sized boils don’t cause permanent scarring, but larger boils may leave a scar.

Patient seeing doctor about a boil

Do you need to see a doctor for a boil?

A boil should burst and heal on its own, without the need to see a doctor. However, you should see a doctor if:

  • your boil lasts for more than 2 weeks without bursting
  • you have a boil and flu-like symptoms, such as a fever, tiredness or feeling generally unwell
  • the redness around the boil starts to spread

A boil is usually caused by an infection, and the above symptoms can be a sign that the infection has spread to the surrounding skin (cellulitis).

If you have a boil on your face, nose or spine, it’s best to see a doctor. A boil that forms in these places can lead to complications and a doctor may want to drain it before the infection has a chance to spread.

Boil on face

Why do I keep getting boils?

You should see a doctor if a boil keeps coming back. They may want to run some tests to work out why you keep getting a boil.

A doctor may also want to rule out some health problems that can increase your chance of getting a boil, such as type-2 diabetes or a weakened immune system.

Carbuncle on elbow

What about carbuncles?

A carbuncle is a group of boils that develop next to each other and join beneath the skin. Carbuncles are generally 3 to 10cm in size and often leak pus from multiple points.

They can be very painful and may cause serious complications if left untreated. If you think you have a carbuncle, visit a doctor.

Treating a boil

You can usually treat a boil yourself with simple remedies like a warm compress to ease symptoms and encourage healing. Get started by reading this article on treating boils at home.


Tidy D. Boils, Carbuncles and Furunculosis | Causes and Treatment [Internet]. Patient.info. 2020 [cited 22 January 2020]. Available here.

Boils and carbuncles - Symptoms and causes [Internet]. Mayo Clinic. 2020 [cited 22 January 2020]. Available here.

Boils, carbuncles, and staphylococcal carriage - NICE CKS [Internet]. Cks.nice.org.uk. 2020 [cited 22 January 2020]. Available here.

British Association of Dermatologists - Patient Information Leaflets (PILs) [Internet]. Bad.org.uk. 2020 [cited 22 January 2020]. Available here.

Boils and carbuncles [Internet]. nhs.uk. 2020 [cited 22 January 2020]. Available here.

Complications of boils and carbuncles - HSE.ie [Internet]. HSE.ie. 2020 [cited 22 January 2020]. Available here.

Boils - Your.MD [Internet]. Your.MD. 2020 [cited 22 January 2020]. Available here.

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