Pilonidal sinus

Also called Pilonidal cyst or Pilonidal abscess

A pilonidal sinus is a small hole or tunnel in the skin at the top of the cleft between the buttocks. It often contains hair and does not always cause symptoms. It is more common in young men, people with a lot of body hair and people who sit for long periods.

Last updated Nov 9, 2026

What it is

It only needs treatment if it becomes infected and painful. An infection may need antibiotics or draining of an abscess.

If it keeps coming back, surgery can remove it. Keeping the area clean and hair-free may help prevent problems.

Common signs

  • Pain and swelling at the top of the buttocks
  • Red, sore skin
  • Pus or blood leaking from a hole
  • A bad smell
  • High temperature

How it is usually diagnosed

  • Examination of the area

Records worth keeping

Keeping these together makes each appointment easier, especially when you see a new doctor:

  • GP notes
  • Surgery notes
  • Wound care plans

Questions to ask your doctor

  • Does it need treatment now?
  • What type of surgery would you recommend?
  • How long will the wound take to heal?

When to get help right away

Call 112 or go to the nearest emergency department if you have:

  • A very painful, spreading swelling with a high temperature: get urgent help the same day

This page is general information. It is not a diagnosis and does not replace a doctor who knows your history. Medfold keeps your records organised; it does not interpret them.

Sources