What are boils?
Boils (also called furuncles) are a deep bacterial infection of hair follicles.
What are the clinical features of boils?
Boils present as one or more tender red spots, lumps or pustules. Careful inspection reveals that the boil is centred on a hair follicle. A boil is a deep form of bacterial folliculitis; superficial folliculitis is sometimes present at the same time. Staphylococcus aureus can be cultured from the skin lesions.
If there are multiple heads, the lesion is called a "carbuncle". Large boils form abscesses, defined as an accumulation of pus within a cavity. Cellulitis may also occur, i.e. infection of the surrounding tissues, and this may cause fever and illness.
Abscess in diabetic
Image supplied by Dr Shahbaz A Janjua
Why do boils occur?
Most people with boils are otherwise healthy and have good personal hygiene. They do however carry Staphylococcus aureus on the surface of their skins (staphylococcal carrier state). Why this occurs is usually not known, but it is estimated that 10–20% of the population are staphylococcal carriers.
Staphylococcus aureus is most commonly carried in the nostrils, armpits, between the legs and in the cleft between the buttocks. It may be transferred to other sites from the nostrils via the finger nails.
Tiny nicks or grazes or something rubbing against the skin can innoculate the bacteria into the wall of a hair follicle which is a weak point in the skin's defences. Once innoculated, the bacteria cause a boil which goes on to run its usual course of about 10 days.
Although most people with boils are otherwise healthy, boils are sometimes related to immune deficiency, anaemia, diabetes, smoking or iron deficiency.
What is the treatment for boils?
Medical treatment of boils
Treatment of boils depends on their severity. Your doctor may give you specific advice and medical treatment, some are listed below:
- Antiseptic or antibacterial soap in your daily bath or shower for a week then twice weekly for several weeks. The cleanser may cause a little dryness.
- Use a hand sanitiser regularly to reduce the chance of reinfecting yourself or others with contaminated hands.
- Antiseptic or antibiotic ointment or gel to apply to the inside of the nostrils.
- Wipe the entire skin surface daily for a week with 70% isopropyl alcohol in water (this will make the skin dry).
- Apply a topical antiseptic such as povidone iodine or chlorhexidine cream to the boils and cover with a square of gauze.
- Your doctor may prescribe an oral antibiotic (usually the penicillin antibiotic flucloxacillin), sometimes for several weeks.
- Other members of the family with boils should also follow a skin cleansing regime. Your doctor may also advise the family to apply topical antibiotic to their nostrils in case they are Staphylococcus aureus carriers as well.
- If the boils fail to clear up, a swab should be taken for microbiological culture, in case of methicillin (meticillin) resistant staphylococci.
- Sometimes, special antibiotics may be prescribed on the recommendation of a specialist, including fusidic acid, clindamycin, rifampicin and cephalosporins.
General measures to prevent boils
- Consult your doctor about your general health.
- If you are overweight, try to reduce your weight; take regular exercise.
- Follow a balanced healthy diet with meat, plenty of fruit and vegetables.
- Avoid smoking.
- Wash your whole body once a day with soap or cleanser and water. Wash your hands several times daily or use antiseptic hand rubs.
- Don't share your flannel or towel with other family members.
- Maintain a clean handkerchief and don't pick your nose!
- Change your underclothes and night attire regularly.
- Consider modifying leisure activities that cause sweating and friction from clothing, such as squash and jogging.
- If you are iron deficient, a course of iron tablets may help reduce infection.
- 1000 mg of vitamin C each day has also been advocated to improve deficient neutrophil function.
- Shallcross LJ, Hayward AC, Johnson AM, Petersen I. Incidence and recurrence of boils and abscesses within the first year: a cohort study in UK primary care. Br J Gen Pract. 2015 Oct;65(639):e668-76. doi: 10.3399/bjgp15X686929. PubMed PMID: 26412844; PubMed Central PMCID: PMC4582880.
On DermNet NZ:
- Bacterial folliculitis
- Staphylococcal infections
- Impetigo – emedicinehealth
- Bacterial infections online course for health professionals
- Boils – Kidshealth.org.nz
- Boils – WebMD
- Boils – emedicinehealth
- Folliculitis – Medscape Reference
- Boils – British Association of Dermatologists
- Patient information: Boil (The Basics) – UpToDate (for subscribers)
Books about skin diseases:
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