Boils - Symptoms of boils and carbuncles

Boils and carbuncles begin as swollen and painful red lumps on the skin, before increasing in size over the following few days.

Boils

Boils can develop anywhere on your skin, but they're most likely to occur in places where there's a combination of hair, friction and sweat, such as the:

neck
face
thighs
armpits
buttocks

Over time, boils grow because there is a build-up of yellowish-white coloured pus. The size of boils can vary significantly. Some boils can grow to the size of a golf ball, but most are about the size of a pea.

It's very important to resist the urge to squeeze the boil because it could lead to more serious complications.

Most boils will burst open eventually, allowing the pus to drain and leaving your skin to heal. This can take from two days to three weeks to happen. Most boils don't leave any scarring unless they're particularly large.

Carbuncles

A carbuncle is a dome-shaped collection of boils that usually develops over the space of a few days. They most often occur on the back of the neck, back or thighs.

A fully grown carbuncle can range in size from 3cm (1.1 inches) to over 10cm (4 inches), and will leak pus from a number of points. You may also have additional symptoms, such as:

a high temperature of 38ºC (100.4ºF) or above
a general feeling of being unwell
feeling weak and exhausted

When to seek medical advice

Contact your GP for advice if you have:

a moderate to large boil that feels soft and spongy to the touch
a carbuncle
a boil on your face or spine – this can sometimes cause serious complications
additional symptoms, such as a high temperature or feeling generally unwell
a secondary infection, such as cellulitis (an infection of the deeper layer of the skin)
a boil and a health condition known to weaken the immune system, such as type 2 diabetes or HIV or AIDS
a boil and you're receiving medical treatment that's known to weaken the immune system, such as chemotherapy
a boil that shows no sign of healing after two weeks