Causes of boils may be:

  • Bacteria invading an area
  • Ingrown hair
  • A splinter or object stuck in the skin
  • Blocked sweat gland or oil duct

Risk Factors

Things that raise the risk of a boil are:

  • Health conditions such as:
    • Diabetes
    • Eczema
    • A weak immune system
    • Obesity
  • Poor hygiene
  • Injury with open wounds
  • Exposure to harsh chemicals
  • Sports or activities with close contact



A boil may cause:

  • A red, swollen, tender skin lump
  • A lump that gets bigger, more painful, and softer
  • A pocket of pus— on top of the boil


The doctor will ask about symptoms and past health. A physical exam may be done. The boil may be swabbed and tested for bacteria.



Treatment depends on the severity of the boils and if there are other health problems. Some boils drain on their own. Others can spread and cause serious problems.

Options may be:

  • Home care, such as:
    • Applying warm compresses or soaking the boil in warm water
    • Cleaning the boil, applying ointments, and bandaging
  • Medical treatment, such as:
    • The doctor makes an incision and drains the boil
    • Antibiotics—for those with certain problems or health conditions


To lower the risk of a boil:

  • Wash the skin daily with soap, then dry thoroughly.
  • Clean and treat any minor skin wounds.
  • Do not wear clothing that is too tight.
  • Be sure to manage eczema, diabetes, or other long-term diseases.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.