Boil (Furuncle) Symptoms, Causes & Treatment Options

A boil, or furuncle, is a bacterial infection of the hair follicle that causes a swollen, red, painful, pus-filled bump on the skin. Boils can resolve on their own or may progress to harmful infections, so see a doctor for severe or concerning boils.

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Contents

  1. Overview
  2. Symptoms
  3. Potential Causes
  4. Treatment, Prevention and Relief
  5. When to Seek Further Consultation
  6. References

What Is A Boil (Furuncle)?

Summary

Boils, or furuncles, are swollen, red, pus-filled nodules on hair-bearing parts of the skin that may be painful and can even cause fevers and malaise. Boils are infections of the deep hair follicle and surrounding skin, usually caused by the bacteria Staphylococcus aureus (“staph”). Boils may occur when staph bacteria enter the skin through small cuts or abrasions. Treatments for boils include a watching and waiting approach in mild cases, and antibiotic medications, or drainage procedures in moderate to severe cases. Boils can sometimes be prevented by taking steps to decolonize or to remove staph aureus from the body with special soaps and other techniques. Occasionally, boils are a sign of an underlying medical condition.

Recommended care

Boil (Furuncle) Symptoms

Main symptoms

Boils are tender red bumps on the skin, that generally have the following common features:

  • Nodules: Boils are generally bumps sticking up from the skin.
  • Tenderness or pain
  • Erythema: Boils will generally be red or pink in color, and the overlying skin will be hot and inflamed.
  • Purulence: Boils may come to a white or yellow head, as they fill with pus.
  • Centered on hair follicle

Accompanying symptoms

Beyond the basic symptoms, boils may develop the following, more advanced features:

  • Carbuncle formation: a carbuncle is a closely packed group of boils
  • Abscess formation: An abscess is a deep pocket of pus or fluid. Boils may develop into larger abscesses if not treated.
  • Cellulitis: This is an infection of the skin that results in red, puffy, hot and inflamed skin. Cellulitis can develop around a boil.
  • Fever: In certain cases, boils may cause fevers, malaise, and a general feeling of overall sickness.

Boil (Furuncle) Causes

Medically, most boils occur due to an infection called a deep bacterial folliculitis. In deep bacterial folliculitis, the deep hair follicle (the site deep in the skin where hairs grow from) becomes infected, usually with a bacteria called Staphylococcus aureus (commonly called “staph”). This infection causes inflammation of the hair follicle which leads to the swelling, redness, pain, and production of pus. From the hair follicle, the infection can spread to the surrounding skin and soft tissue, and even the blood [1].

The bacteria that causes most boils, Staphylococcus aureus, is actually quite common – it is native to human skin and can be carried in the nostrils, armpits, and fingernails. It is not always clear why a boil occurs when it does, though often it is because the staph bacteria have entered into deeper levels of the skin through a cut or abrasion.

Other causes of boils

Certain medical conditions that are separate from staphylococcal folliculitis may also cause boils, recurring boils, or boil-like eruptions. Some of these conditions are listed below:

  • Hyper IgE (Job) syndrome: an immune system deficiency that leads to a predisposition to boils on the skin
  • Iron deficiency anemia: can cause immunologic deficiencies that may lead to infections like boils
  • Diabetes: may lead to immune deficiencies, as described above
  • Hidradenitis suppurativa: a chronic skin disease that causes non-infectious boils and lesions in the armpits and other areas

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Treatment Options, Relief, and Prevention for a Boil (Furuncle)

Treatment

Treatment of boils begins with proper hygiene and covering of the boil. More serious boils will require medical treatments that may include pills or ointments. Some boils will require a small procedure to drain their contents.

  • Topical antiseptics: These medications remove bacteria from the surface of the skin. Examples include povidone-iodine (Betadine) or chlorhexidine (Chlora-prep). In less severe cases, simple disinfecting the skin and covering the boil will allow it to go away on its own.
  • Oral antibiotics: If boils fail to clear, progress despite treatment, progress to cellulitis or abscess, or if they cause a fever or malaise, oral antibiotics are likely necessary. Your doctor’s choice of antibiotics will take into account the most likely causative bacteria, the severity of the boil, and individual medical conditions like allergies and kidney function. One of the most common choices is cephalexin (Keflex), but many options are available.
  • Intravenous antibiotics: In rare cases, if your doctor believes that you have a severe infection, or thinks that your boils are being caused by a drug-resistant bacteria species (like methicillin-resistant Staphylococcus aureus, or “MRSA”), you may need intravenous antibiotics which could require a hospital stay.
  • Incision and drainage: Large boils may require a doctor to perform a procedure called an incision and drainage. In this procedure, the doctor will make a small incision in the boil and drain out the pus, relieving pressure and removing infectious material. Sometimes the boil will need to be packed with sterile gauze after this procedure [2].
  • Do not attempt drainage at home! Never attempt to squeeze pus out of a boil at home or on your own. This can result in injury and can spread the infection.

Prevention

Certain people will have recurrent boils. In these cases, steps can be taken to reduce the likelihood of recurrence, and prevent the spread of boils to others. The biggest task in these cases is to de-colonize or reduce the amount of Staphylococcus aureus on the body and in your environment. Decolonization techniques and other prevention techniques are listed below:

  • Hand washing: Hand hygiene – washing hands after touching the boil and using hand sanitizer regularly - will prevent the spread of existing boils and the development of new ones.
  • Antibacterial soap: Washing daily, or even several times per week with an antiseptic soap like Hibiclens can reduce staph on the skin.
  • Prevent nasal carriage and transmission: Reduce staph populations carried in the nose by applying antibiotic ointment to the inside of the nostrils. Prevent transmission from the nose by not picking the nose.
  • Prevent anal carriage and transmission: Staph may also live in the gluteal cleft and anus, especially in small children. These areas can also be decolonized using antibiotic ointments, antibacterial soap, and by always wearing clean underpants.
  • Family decolonization: Other family members, even those who don’t get boils, can remain colonized and spread bacteria. Consider decolonizing the whole family at once, and don’t share towels, razors, or other personal items that may carry bacteria.

When to Seek Further Consultation for a Boil (Furuncle)

Small, lone boils can generally be cared for at home, by careful washing, bandaging, and waiting. However, boils can be dangerous in some cases. See a doctor if you experience any of the following:

  • Boil worsening rapidly, becoming larger or deeper
  • Very painful
  • Fever, chills, malaise with a boil
  • Recurrent boils: If recurrent, boils may be a part of an underlying medical condition, as described above.
  • Boils on the face: Certain parts of the face are linked closely to the brain’s blood supply, so infections here must be treated with caution.
  • Multiple boils: again, may be part of an underlying condition