A pilonidal cyst is a fluid-filled sac. It forms beneath the skin near your tailbone, at the top of the crease of your buttocks. A pilonidal cyst that is not large or infected may not cause symptoms or problems.

If the cyst becomes irritated or infected, it may fill with pus. This causes pain and swelling (pilonidal abscess). An infected cyst may need to be treated with medicine, drained, or removed.




What are the causes?

The cause of a pilonidal cyst is not known. One cause may be a hair that grows into your skin (ingrown hair).

What increases the risk?

Pilonidal cysts are more common in boys and men. Risk factors include:

What are the signs or symptoms?

Signs and symptoms of a pilonidal cyst may include:

How is this diagnosed?

Your health care provider may diagnose a pilonidal cyst based on your symptoms and a physical exam. The health care provider may do a blood test to check for infection. If your cyst is draining pus, your health care provider may take a sample of the drainage to be tested at a laboratory.

How is this treated?

Surgery is the usual treatment for an infected pilonidal cyst. You may also have to take medicines before surgery. The type of surgery you have depends on the size and severity of the infected cyst. The different kinds of surgery include:

Follow these instructions at home:

Contact a health care provider if: