Complications of boils and carbuncles  

Although most boils don't cause further problems, this isn't always the case.


Scarring can sometimes occur after a larger boil or carbuncle. These scars never disappear completely, but they do fade with time and become less noticeable.

If you're particularly concerned about scars, there are a number of treatments, including:

However, it's unlikely your local clinical commissioning group (CCG) will fund these treatments unless it can be shown your scars are causing you considerable psychological distress.

A simpler alternative is to use make-up to conceal any scars you have. Camouflage make-up specially designed for covering scars is available over the counter at pharmacies.

Read more about treating scars.

Spread of infection

The bacteria inside a boil or carbuncle can sometimes spread to other parts of the body and trigger a secondary infection.

Cellulitis (an infection of the deeper layers of skin) is the most common secondary infection associated with boils and carbuncles.

Less common secondary infections include:

  • impetigo – a highly contagious skin infection that causes sores and blisters
  • septic arthritis – an infection of a joint
  • osteomyelitis – an infection that develops inside a bone
  • endocarditis – an infection of the inner layer of the heart
  • septicaemia – an infection of the blood
  • brain abscess – a collection of pus that develops inside the brain

Some of these secondary infections need to be treated with antibiotic injections. In the case of septicaemia and brain abscess, you will be admitted to an intensive care unit (ICU).

Cavernous sinus thrombosis

Cavernous sinus thrombosis is a very rare but potentially life threatening complication of a boil. It occurs when an infection triggers a blood clot in the spaces behind the eye socket. The clot begins to increase the pressure on the brain, causing symptoms such as:

  • a sharp and severe headache
  • swelling of the eyes
  • eye pain that's often severe

Without prompt treatment with antibiotics, cavernous sinus thrombosis can be fatal. However, this condition is very rare.

Read more about cavernous sinus thrombosis.

Page last reviewed: 30/01/2015

Next review due: 30/05/2017