A boil is a skin infection, often caused by the Staphylococcus aureus bacteria. This bacteria is often found on the surface of your skin or inside your nose and can live there without causing you any harm. However, the bacteria can get into your skin when it becomes broken, cut or grazed, causing a boil to develop.

It is most common for boils to start in one or more of your hair follicles. The boil first appears as a red, tender area, which eventually becomes hard and firm.

The boil will then soften as it fills with white blood cells, which your body sends to the area to tackle the infection. This, along with proteins and bacteria, creates a swollen sore that may contain pus.

If you have several boils that appear in a group, this is called a carbuncle, and it is a sign of a more severe infection.

Symptoms to look out for include:

  • A tender, red, swollen bump
  • A pus filled bump, with a head that may weep
  • A bump that is less than 2.5 cm in diameter
  • The skin around the boil may be red and tender

Boils can develop on different areas of your body, the most common include your:

  • Face
  • Armpits
  • Groin area
  • Neck
  • Buttocks
  • Inner thighs

Most boils do not need treatment and will get better on their own.

You can treat a boil at home with a heat pack or a warm moist face cloth – apply it to the boil three to four times daily. The heat will help to increase circulation, which will allow your body to fight off the infection better.

When the boil bursts, it is a good idea to keep it covered with a sterile dressing to prevent more bacteria getting into the wound, and to stop the infection from spreading. Do not ever be tempted to squeeze the boil, as it could cause the infection to spread.

Often, boils will go away on their own. But in rare cases, they can develop into a more severe infection, including cellulitis or even sepsis in very rare cases. Things to look out for include if:

  • The skin around the boil turns red, red streaks appear or it becomes severely painful
  • You develop new boils around the original boil
  • You develop a fever
  • Your lymph glands become swollen

If you believe you have signs of a severe infection, speak to a GP as you may need treatment. You should also speak to a GP if:

  • The boil is on your face, nose or spine, as this can lead to complications
  • The boil does not heal within 2 weeks

A doctor can usually diagnose your boil, skin infection or other skin condition, based on appearance alone.

If they cannot diagnose the condition just by looking at it, you may be referred for further testing, such as a skin swab or blood test. You may also be referred for tests if you have a boil that is not responding to treatment, is recurring, if you have more than one, or if you have a weakened immune system.

If you have a severe infection, then you may be prescribed antibiotics. The antibiotics may be in the form of a cream or be an oral medication.

If the boil does not heal on its own, it may need to be drained under local anaesthetic by either a GP or in hospital.

There are certain things you can do to help prevent boils developing, including washing your skin regularly with antibacterial soap, protecting and cleaning any cuts on your skin and maintaining a healthy lifestyle and diet.

Some people who are thought to carry the Staph germ in their nose may need to use an antiseptic or antibiotic cream in their nostrils for a few weeks. A GP can help you with this.

Boils can be spread around your body or from person to person, so if you have one, it is important to be extra careful, especially after touching the affected area and not sharing towels with family members or friends can help prevent the infection from spreading to others.