Boils, Carbuncles and Furunculosis - Causes

Authored by Dr Colin Tidy, 24 Aug 2016

Patient is a certified member of
The Information Standard

Reviewed by:
Dr Helen Huins, 24 Aug 2016

Boils can develop in any hairy area of skin. In particular, in sites where there is friction, or where the skin is sweaty. For example, they can appear on the neck, face, armpits, arms, buttocks and around the back passage (anus). A boil in the ear canal may be very painful. Carbuncles most commonly develop on the back of the neck or on the thighs.

A boil or carbuncle can occur in anyone at any age. However, they are uncommon in children and most commonly occur in teenagers and young adults.

You have a higher risk of developing a boil or carbuncle if you:

  • Have other skin conditions that may cause you to scratch and damage the skin - for example, eczema or scabies.
  • Are extremely overweight (obese).
  • Have a poor immune system.
  • Have an illness making you frail or generally unwell.
  • Are a carrier of staphylococcal germs (bacteria) - see below.

Recurring boils

If you develop recurring boils (chronic furunculosis), your doctor may suggest some tests to look for an underlying cause. For example, to check if you have a poor immune system. You may be prone to boils just because you're generally run down and tired. But it's important to check there isn't any underlying problem, such as type 2 diabetes.

One cause of recurring boils if you are otherwise healthy is that you, or someone in your family or household, may be a carrier of staphylococcal germs (bacteria). This means that a certain number of these bacteria live harmlessly on your skin, or in your nose. If you are a carrier, you tend to be more prone to skin infections and boils. In particular, these bacteria may quickly invade and multiply in broken skin following a minor cut or injury. Treatment with antibiotics and/or antibiotic nasal cream may clear staphylococcal bacteria from carriers and reduce the chance of boils, or other types of skin infection, from coming back.

Further reading and references

Hello, i have been getting boils in my groin area and thighs for about 4 years now. i have gone to my dr many many times. I have had blood tests to rule out diabeties. they have never taken a swap...

maria99745
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