Symptoms · Lower back
A painful lump or discharge above the buttocks, near the tailbone
The short answer
A painful, swollen lump in the crease above the buttocks, sometimes with pus or a bad-smelling discharge and a small hole in the skin, is most often a pilonidal abscess or sinus. It is linked to hair trapped under the skin, and it is not caused by poor hygiene. An abscess needs to be drained. A sinus tends to come back unless it is treated and the area is kept free of hair. See a doctor. Go to the emergency room if you have fever or the redness is spreading.
How patients describe it
- A boil above my buttocks
- Pain when I sit
- Pus from the crease of my buttocks
- A small hole at the tailbone
- A lump at the end of my spine
Go to the emergency room now if you have
- Fever or chills
- Redness spreading beyond the swelling
- Severe pain that stops you sitting or walking
- Diabetes or a weak immune system with this swelling
- Heavy bleeding
What can cause it
Pilonidal abscess
A hot, tender swelling in the crease above the buttocks, often with fever.
Next step: Examination and drainage of the pus.
Pilonidal sinus
A small hole or pits in the crease with repeated discharge, hair and soreness.
Next step: See a surgeon about treatment.
A boil or infected hair follicle
A single tender lump with a white head, not usually near the crease itself.
Next step: Examination; warm compresses, and drainage if needed.
Anal abscess or fistula
Pain and discharge close to the anus, not at the tailbone.
Next step: See a surgeon, because it needs different treatment.
What you can do now
- Sit in a warm bath 2–3 times a day to ease the pain
- Keep the area clean and dry, and avoid long periods of sitting
- Do not squeeze, cut or burst the lump yourself
- Ask your doctor about keeping the area free of hair, because it lowers the chance of the problem coming back
- Book a clinic visit if the lump keeps coming back or keeps leaking
Tests your doctor may order
- Examination is usually enough
- An ultrasound or MRI scan for a repeated or complex sinus
When is surgery needed?
- An abscess is drained by a small cut.
- A sinus that keeps coming back is treated by an operation. The options are open excision, excision with closure, or laser treatment.
- Keeping the area clean and free of hair after treatment lowers the chance of it coming back.
Related operation guides
Questions people ask
Is it caused by poor hygiene?
No. It comes from hair and friction in the crease above the buttocks, and it is common in people with thick body hair or who sit for long periods.
Will it come back after treatment?
It can. About 5–10 in 100 people have it again after open excision, 10–15 in 100 after closure, and 15–20 in 100 after laser treatment.
Can antibiotics cure it?
Antibiotics may calm an infection, but they do not remove the sinus, and an abscess needs to be drained.
How soon can I go back to work?
It depends on the operation: about 1 week after laser, 2–3 weeks after closure, and 4–6 weeks after open excision.
This page gives general information and does not replace the advice of your treating team. In an emergency, go to the nearest emergency room.