Are Boils Contagious?

Boils (furuncles) are infections under the skin that occur when bacteria infect a hair follicle or oil gland, resulting in painful, pus-filled lumps. When several boils form in the same area and join together it is called a carbuncle.

Symptoms of boils include: 

• A painful, red, hard lump under the skin 
• Lump is white or yellow and may open in the center
• May start out small and grow quickly
• The larger the lump, the more painful it usually is

If the infection progresses, symptoms may include:

• Swollen skin around the boil
• Redness in the area surrounding the boil
• Additional boils near the original one
• Fever
• Swollen lymph nodes near the boil

Boils are usually caused by Staphylococcus (staph) bacterium. Staph may be present on skin normally, but it can enter the body through tiny breaks in the skin from cuts, scrapes, shaving, ingrown hairs, insect bites, skin conditions, or by traveling down a hair to the follicle. 

Risk factors for developing boils include: 

• Close contact with people who have active infected boils
• People who have a compromised immune system
• Diabetes
• Poor nutrition
• Poor hygiene
• Exposure to chemicals that irritate the skin
• Infection with community-acquired methicillin-resistant S. aureus (CA-MRSA)
• Intravenous drug use
• Exposure to whirlpool footbaths at nail salons

Active boils are contagious because the Staphylococcus (staph) bacteria that cause them is contagious. The infection that causes boils can be transmitted through skin-to-skin contact or sharing objects.

Boils are contagious until they are drained and have healed.

Boils are diagnosed with a patient history and physical examination of the skin. A healthcare professional may take a sample of pus from inside the boil to determine the type of bacteria that caused the boil.

In patients who have recurrent boils, blood tests may be indicated to determine if there is an underlying condition such as diabetes that can make a person more susceptible to developing boils.

Small boils can often be treated with self-care at home. Boils need to open and drain so they can heal. In some cases, boils will open and drain on their own. Home treatment to help drain a boil includes: 

• Warm pressure 
• Wet a clean washcloth with warm water and apply to the boil
• When the wash cloth cools, reheat it with warm water and reapply to the boil
• Repeat for 10 to 15 minutes every few hours
• Wash hands thoroughly with soap and water each time after touching the boil
• Do not squeeze or pop a boil because this can spread infection
• Once the boil opens and drains, it should heal on its own within a few weeks

For boils that are larger than a pea or have a large area of redness around them indicating deeper infection, see a doctor. Medical treatment for boils includes: 

• Incision and drainage (I&D), which involves cutting the boil open to drain
• Antibiotics to treat infection
  • Sulfamethoxazole/trimethoprim (Bactrim)
  • Mupirocin (Bactroban)
  • Cephalexin (Keflex)
  • Clindamycin (Cleocin)
  • Doxycycline (Doryx)
  • Vancomycin (Vancocin)

Complications of boils include:

• Scarring
• Infections 
  • Cellulitis, a secondary infection of the deeper layers of the skin
  • Impetigo, a skin infection
  • Septic arthritis (joint infection)
  • Osteomyelitis (bone infection)
  • Endocarditis (heart infection)
  • Septicemia (blood infection)
•  Brain abscess