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Pilonidal sinus


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An infected pilonidal sinus is painful and swollen and may bleed or leak pus.

If your pilonidal sinus is not infected, you do not need treatment. Keep the area between your buttocks clean.

An infected pilonidal sinus usually needs to be cut and the pus drained. In some cases, you may need antibiotics or surgery.

It's not clear what causes a pilonidal sinus. A skin problem, pressure or friction may cause hair between the buttocks to be pushed inwards.

A pilonidal sinus is a small hole at the top of your bottom, between your buttocks. Treatment is usually only needed if it becomes infected.

Page last reviewed: 16/11/2023
Next review due: 16/11/2026