Pilonidal Disease

What is Pilonidal Disease?

Pilonidal Disease is a chronic skin infection caused by hairs becoming embedded in the skin just above the crease in the buttocks. In the vast majority of cases, Pilonidal Disease affects younger people (15 – 30s), and occurs after puberty when the pilosebaceous gland causes changes in body hair.

It is about twice as common in men as women, those who are obese and people with particularly thick body hair, and can be associated with poor personal hygiene or injuries in the area.

The disease happens because the hair follicle under the skin breaks and lets in infective bacteria which can lead to inflammation, draining sinuses, fistulae, or abscesses.


Pilonidal Disease can occur suddenly or exist as a low-grade infection over several years.  Symptoms vary from a small dimple at the site to a large and painful mass under the skin. Fluid may seep from the area: it can be clear, cloudy, or bloody. If infected the area will become red and tender and any discharge will have a bad smell. It may cause fever, nausea (feeling sick), or a feeling of being generally under-the-weather.


A physical examination of the area by a GP is usually all that is needed.


Treatment options vary depending on the extent of the infection. An abscess may be incised and drained under a local anaesthetic  which will relieve the inflammation and pain. A chronic sinus may need to be treated surgically.

If Pilonidal disease is complex or recurring a surgical option will be necessary and may include either an unroofing, where the topmost layers of infected material are taken, or an excision, where all of the inflamed tissue will be taken away. The resulting wound can be left open or closed with flaps. If open it will be packed and changed regularly. Healing will take several weeks with an open wound and will require a lot of care, but as the wound will heal from the bottom up thereby reducing the chances of a subsequent infection, this is usually a more successful option.