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What is Pilonidal Disease and What Causes It?

Pilonidal disease is a chronic infection of the skin in the region of the buttock crease. The condition results from a reaction to hairs embedded in the skin, commonly occurring in the cleft between the buttocks. The disease is more common in men than women and frequently occurs between puberty and age 40. It is also common in obese people and those with thick, stiff body hair.

What are the Symptoms?

Symptoms vary from a small dimple to a large painful mass. Often the area will drain fluid that may be clear, cloudy or bloody. With infection, the area becomes red, tender, and the drainage (pus) will have a foul odor. The infection may also cause fever, malaise, or nausea.

There are several common patterns of this disease. Nearly all patients have an episode of an acute abscess (the area is swollen, tender, and may drain pus). After the abscess resolves, either by itself or with medical assistance, many patients develop a pilonidal sinus. The sinus is a cavity below the skin surface that connects to the surface with one or more small openings or tracts. Although a few of these sinus tracts may resolve without therapy, most patients need a small operation to eliminate them.

A small number of patients develop recurrent infections and inflammation of these sinus tracts. The chronic disease causes episodes of swelling, pain, and drainage. Surgery is almost always required to resolve this condition.

How is Pilonidal Disease Treated?

The treatment depends on the disease pattern. An acute abscess is managed with an incision and drained to release the pus, and reduce the inflammation and pain. This procedure usually can be performed in the office with local anesthesia. A chronic sinus or recurrent abscesses typically require surgery.

What Care is Required after Surgery?

If the wound is left open, dressings or packing will be needed to help remove secretions and to allow the wound to heal from the bottom up. If the wound is closed, it will need to be kept clean and dry until the skin is completely healed.

After healing, the skin in the buttocks crease must be kept clean and free of hair. This is accomplished by shaving or using a hair removal agent every two or three weeks until age 30. After age 30, the hair shaft thins, becomes softer and the buttock cleft becomes less deep.

Frequently Asked Questions

Why did I get a cyst on the bottom of my spine?

As explained above, this is a frequent developmental problem that is very common in young people, quite debilitating, but easily managed surgically.

Is this cyst connected to my spine?

No, it is just a cyst in the skin, with accumulation of greasy cyst material, hair, and bacteria. Usually, it’s associated with a pin-hole opening.

Is it dangerous?

Not usually. A fairly simple surgical procedure can be done to clear up the problem.

What options do I have, and do I always need surgery?

One option is to take antibiotics, hope to clear the infection and wait to see if it recurs. Sometimes, a drainage of the abscess is necessary along with the antibiotics, to clear the infection. The underlying cyst, though, will still be there, and is prone to re-infection

Surgical options?

One option is to just have the infected cyst drained. The second option is to have a two-stage procedure, requiring that the abscess be drained, then surgically removed at a later date

Call UHS if any of the following happens:

  • Worsening Symptoms
  • Temperature over 102 F
  • Onset of chills about 24 hours after treatment has started
  • Nausea, vomiting or diarrhea
  • Drowsiness or lethargy
  • Recurrence of symptoms
  • Lack of improvement.


In an emergency go to Mount Nittany Medical Center or call 911 for an ambulance.

Test Results and Advice Nurse

Send a secure message to the advice nurse via myUHS or call 814-865-4UHS (4847) (Press 3). 


Schedule an appointment online or by calling the UHS.  

This content is reviewed periodically and is subject to change as new health information becomes available. This information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis, or treatment by a healthcare professional. 3/23/20

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