Potentially symptom of diabetes, chronic granulomatous disease, Hyper IgE syndrome – but more usually just an individual thing, or a nasty strain of staphlycoccus aureus.

GOS says if otherwise well (no other abscesses, no colitis, no weird organisms eg Serratia) then consider eradication with:

• Naseptin – a medication taken four times a day for a period of 10 day.s
• Chlorhexidine shower or bath and hairwash every day for a period of 14 days.
• Keep a separate towel for each member of the family, change for a clean towel every two days and wash the dirty towels on a hot wash cycle.

[http://www.gosh.nhs.uk/medical-information-0/search-medical-conditions/recurrent-boils]