Skin boils are inflamed bumps that begin under the surface of the skin when bacteria infect at least one hair follicle (the tubular shafts from which hair grows). Also known as furuncles, boils appear on the skin surface as red lumps about a half-inch (1.27 centimeters) in diameter. Boils usually fill with pus about 24 hours after initially appearing. They often are painful and hot to the touch and may continue to grow for between five and seven days. They will sometimes swell to the size of a golf ball before a yellow-white tip appears. Soon after, the boil usually bursts and drains. Most boils heal within two weeks, although they generally must drain before they will heal.
A boil is a type of abscess, which is a collection of pus and debris surrounded by skin that is pink to deep red. Boils most often appear on the face, neck, armpits, breasts, buttocks or thighs. These hair growth areas are also subject to regular perspiration (sweat) or friction, both of which can lead to the formation of boils.
Boils form when staph bacteria – usually Staphylococcus aureus, but sometimes another fungi or bacteria – infect one or more hair follicles. This condition is known as folliculitis, and it often appears as a tiny white pimple at the base of a hair. Normally, these bacteria remain at the surface of the skin. However, cuts, scratches or other breaks in the skin offer an entry point for staph infections into the tissues of the hair follicle and the subcutaneous tissue (the bottom layer of the skin). In some cases, the cause of infection remains unknown.
When staph bacteria enter the body, special white blood cells (neutrophils) rush in and target the infection in an attempt to destroy it. This leads to inflammation and the formation of pus, which is made up of a combination of old white blood cells, bacteria and dead skin cells.
When several boils appear together on one part of the body, it is called a carbuncle. These small, shallow clusters of boils develop more slowly than individual boils, and typically cause a deeper, more severe infection. They tend to affect the back of the neck, shoulders and thighs, and are especially likely to afflict older men.
Although a single boil is usually a minor condition that does not require medical treatment, multiple boils at the same time may indicate a more serious condition. Individuals who have multiple boils at one time - including a carbuncle - should seek medical attention.
Boils often resemble cystic acne, a condition that causes inflamed, painful lumps. However, cystic acne usually persists for long periods of time, whereas boils appear intermittently. Boils also tend to be more painful and reddened and inflamed around the edges than cystic acne. Boils are particularly painful when they occur in the ear canal or nose. When a boil appears on an eyelid, it is called a stye.
A boil occurs as a result of folliculitis, which is inflammation of the hair follicle (the tubular shafts from which hair grows) due to infection with Staphylococcus aureus (staph) or another fungi or bacteria. Symptoms of folliculitis include pus in the hair follicle, irritation or redness in the hair follicle or hair damage.
In addition to the boil itself, staph infections may cause other symptoms. For example, the skin surrounding the boil may become red and swollen. In some cases, a fever may accompany a boil, particularly when multiple boils join together to form a carbuncle. Patients may also feel fatigued or experience malaise (a general ill feeling).
On rare occasions, bacteria from a boil will enter the bloodstream, where it is able to travel to other parts of the body. This is a potentially life-threatening condition known as septicemia, and it may cause initial symptoms such as chills, soaring fever and rapid heart rate. As the condition progresses, the patient may go into shock, a condition marked by falling blood pressure and body temperature, confusion, clotting abnormalities and bleeding into the skin.
- Abscess (a collection of pus and debris) of kidneys or other internal organs
- Brain infection or abscess
- Endocarditis (inflammation of the lining of the heart and its valves)
- Osteomyelitis (inflammation of the bone and bone marrow)
- Permanent scarring of the skin
- Spinal cord infection or abscess
Boils form when staph bacteria – usually Staphylococcus aureus, but sometimes another fungi or bacteria – infect one or more hair follicles (the tubular shafts from which hair grows). This condition is known as folliculitis, and it often appears as a tiny white pimple at the base of a hair. When the staph bacteria enter the body, special white blood cells (neutrophils) target the infection in an effort to destroy it. This causes inflammation and pus formation, and ultimately results in a skin boil. Staph bacteria are commonly found on the skin, but also can be found in the throat and nasal passages.
People with certain conditions or exposures are at higher risk for developing boils. Skin conditions that damage the protective barrier of the skin create entry points for infection.
These include acne (occurs when tiny holes on the surface of the skin become clogged, causing bumps), eczema (inflammatory skin disease with lesions that usually appear very dry, thickened or scaly) and chafing (continuous rubbing of the skin that causes redness or soreness). In addition, a suppressed immune system due to certain diseases (e.g., AIDS, diabetes) or certain drugs (e.g., long-term use of corticosteroids) puts people at greater risk for boils. Poor health also makes it harder for the immune system to battle infection.
- Poor hygiene. People who do not bathe frequently and allow bacteria to build up on the skin are at higher risk for boils. In addition, those who are confined to a prone position may be susceptible to bed sores, which can lead to infection and boils.
- Open wounds. Wounds suffered from trauma or other causes provide staph bacteria with an entry point into the body.
- Exposure to harsh chemicals. These can irritate the skin, creating entry points for infection.
In many cases, boils can be treated with home-based care. Boils will rupture on their own after a certain period of time. While waiting for the boil to rupture, patients should gently wash the boil twice a day and apply an over-the-counter antibiotic (used to combat bacteria) before covering it with a bandage. Warm washcloths or compresses can also be applied to the boil to help it drain more quickly. Adding one teaspoon of salt to a quart of boiling water can create a saltwater solution. Once the water cools, soak the cloth or compress in the saltwater before applying it to the boil. Saltwater will help the boil rupture more quickly.
After rupturing, boils usually take about two weeks to heal. Small boils usually do not leave a scar, but larger boils may leave a mark. Patients should not try to lance or squeeze their own boils, as this can cause other areas of skin to become infected. Patients should always wash their hands after touching the boil, and clothing, compresses and towels that have touched the affected area should be laundered in very hot water.
Patients should contact a physician if their boil lasts longer than two weeks, or if they develop more than one boil, including clusters of boils (carbuncles). Children (especially infants) and the elderly should also seek medical attention whenever boils appear. Other conditions that may require medical attention include:
- Boils accompanied by fever
- Frequent appearance of new boils
- Great pain at the site of the boil or rapid worsening of the boil
- Presence of an immune-suppressing condition, such as an HIV or an organ transplant
- Red lines that radiate from the boil (may indicate infection in the bloodstream)
- Boils around or within the nose, or within the external ear canal
A physician will diagnose a boil through a physical examination. In some cases, additional testing may be performed to determine the nature of the bacteria in the boil, or to search for underlying diseases – such as diabetes – that may be responsible for the boil.
Antibiotics or surgical drainage (via a small incision at the tip of the boil) may be used to help get rid of the infection. Making a surgical incision in a boil (lancing) relieves pain, speeds recovery and reduces the risk of scarring. A physician may lance boils that are especially large. If the infection is deep and cannot be completely cleared through this technique, the boil may be covered with sterile gauze while the pus drains.
In recent years, a strain of staph known as methicillin-resistant Staphylococcus aureus (MRSA) has begun to affect more people. This form of staph – which used to be largely confined to hospitals – is highly contagious and is often spread through shared athletic equipment or towels. Patients whose boils are infected with this form of bacteria require treatment with antibiotics that can prevent the condition from becoming fatal. However, MSRA is resistant to penicillin.
Boils cannot always be prevented. However, people can take several steps to reduce the risk of becoming infected with the staph bacteria responsible for causing boils. For example, people who suffer cuts or scrapes should wash them thoroughly with soap and water before applying an over-the-counter antibiotic ointment (used to combat bacteria) and keep the wound covered with a bandage until it is fully healed. It is also beneficial to avoid contact with other people’s wounds or bandages.
In addition, a healthy diet can keep the immune system in top condition. Healthy foods include grains, fresh fruits and vegetables and modest amounts of lean protein.
Wearing the right clothes during exercise and everyday activities can prevent chafing, which occurs when skin rubs together and becomes irritated. Chafing can open the skin, making it vulnerable to staph infection. It is recommended that individuals wear loose-fitting clothing to avoid chafing.
It is also recommended that Staphylococcus infection in the nose or in other parts of the body be treated promptly with antibiotics, which helps prevent these infections from causing boils.
Other steps to minimize the risk of skin boils include exercising proper hygiene to reduce the buildup of bacteria on the skin (e.g., frequently and thoroughly washing hands with soap and water), and properly managing diseases such as AIDS and diabetes that may weaken the immune system. Patients should also avoid sharing personal items (e.g., towels, razors) with other people.
Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctors the following questions related to skin boils:
- Do my symptoms indicate that I have skin boils?
- What may have caused me to develop skin boils?
- Do my boils require medical treatment? If so, what are my treatment options?
- Are boils potentially dangerous to my health?
- How long will it take my boils to heal?
- Is it safe to drain the boil myself?
- Will I likely develop skin boils again in the future?
- How can I prevent boils from forming?
- How can I prevent my boils from becoming infected?
- How will I know if my boils become infected?
- Under what circumstances should I seek medical attention for a skin boil?
Decrease activity until the boil heals. Avoid sweating and avoid contact sports (such as wrestling) while lesions are present.
- You or a family member has a boil.
- The following occur during treatment:
- Symptoms don't improve in 3 to 4 days, despite treatment.
- New boils appear.
- Other family members develop boils.
- New, unexplained symptoms develop. Drugs used in treatment may produce side effects.