Pilonidal Disease


Pilonidal disease (sometimes also referred to as 'pilonidal sinus disease' or 'PNS') is a chronic skin condition that develops on the lower back, just where the buttocks meet (the 'natal cleft'), where sinuses (small holes) appear in the skin. This becomes a problem when one of these sinuses becomes infected and either a cyst or an abscess forms. If this occurs, it is referred to as 'acute pilonidal disease'. The ongoing formation of sinuses in the natal cleft can also lead to 'chronic pilonidal disease'.

Although it can affect both sexes, it is more common in the younger male population.


The main symptoms of pilonidal disease are pain in the affected area, and in some cases a discharge of pus from sinuses (which may smell quite bad). Very rarely some people also develop a fever. Pilonidal disease normally develops over time, but it can also develop quite rapidly.


It is not clear exactly why pilonidal disease develops. The word 'pilonidal' literally means 'hair nest' in Latin and the presence of hair in the natal cleft is thought to be responsible for the development of the condition, either due to the collection of back hair or hair from the buttock which irritates the skin causing a discharging sinus or an abscess.

Some people are more prone to developing the condition than others, particularly:

  • Men (although not unknown in women).
  • People aged 15-40 (possibly linked to hormonal changes in puberty).
  • People who are overweight / obese.
  • Where there is a pre-existing skin condition.
  • People with more body hair or coarser body hair.
  • People with a deeper natal cleft.
  • People who habitually sit for long periods (for example truck drivers or keen horse riders).

Tests & Diagnosis

Visual examination is generally sufficient to diagnose the condition. If a pilonidal cyst has developed this will appear as a lump or swelling in the natal cleft. Where there is severe infection, the swelling may be very painful, large and red.


Treatment will depend on the severity of the condition – in some cases a course of antibiotics or a lancing of any abscess will be adequate. Where the condition is recurring or where there are multiple sinuses, pilonidal sinus treatment may be recommended. Keeping the area void of any hairs permanently, e.g. via laser hair removal, is also important.

Related Information

Pilonidal Sinus Treatment