Boils
Boils can develop anywhere on your skin, but they're most likely to occur in places where there's a combination of growing hair, friction and sweat, such as the:
- neck
- face
- thighs
- armpits
- buttocks
Boils can be single or develop in clusters. When a boil first forms, it will appear as a swollen, painful red lump that's similar in size to a twenty pence piece. Over the next few days, the boil will begin to grow.
The size of boils can vary significantly. Some boils can grow to the size of a golf ball. Yellowish-white coloured pus will begin to build up at the centre or tip of the boil. However, it's very important to resist the urge to squeeze the boil because it could lead to more serious complications.
Eventually, the boil will usually burst open and the pus will drain away, 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 red, hard painful lump that grows over the space of a few days. It usually develops on the back of the neck, the 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 and ‘out of sorts’
- 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 – 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 that's 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
