A pilonidal sinus is a small tunnel that develops at the top of the crease in the buttocks. Trapped hair around the buttocks crease can lead to an abscess, and a pilonidal sinus may develop as a result.

If people have a pilonidal sinus, they may have discomfort and irritation around the tailbone area. In some cases, a pilonidal sinus may resolve by itself, but people may require treatment, such as abscess drainage or sinus removal.

In this article, we look at symptoms, causes, treatment options, recovery, and outlook for a pilonidal sinus.

young medical professional walking down hospital hallwayShare on Pinterest
Maskot/Getty Images

According to the American Society of Colon and Rectal Surgeons (ASCRS), the cause of pilonidal sinus is not clear.

It may be due to hair that grows in the crease of the buttocks, or natal cleft. Alternatively, trapped hair follicles may lead to hair and bacteria entering the skin. This can result in inflammation and pus forming in an abscess.

Once the abscess heals, either on its own or with treatment, a pilonidal sinus may develop. The sinus is like a pipe just under the skin with tiny openings to the surface of the skin. People with a pilonidal sinus need to take care of the area to prevent future abscesses and infections.

A pilonidal sinus affects the natal cleft, which is the top of the crease of the buttocks, just under the tailbone.

Symptoms can range from mild to severe, depending on the level of infection. If people have a pilonidal sinus, they may have the following symptoms:

  • small dimple in the skin
  • irritation or discomfort
  • painful mass, which may be an abscess
  • drainage from the area, which may be a clear, cloudy, or bloody fluid
  • red, tender area
  • foul-smelling pus
  • fever
  • nausea

Risk factors for pilonidal sinus include:

  • being male
  • having a family history of pilonidal disease
  • being overweight
  • experiencing trauma or irritation in the area
  • having a sedentary lifestyle or sitting down for long periods
  • having a lot of hair around the buttocks
  • practicing poor hygiene habits
  • being younger, as pilonidal sinus is more common in young adults

If people have no symptoms or signs of infection from a pilonidal sinus, they may not require treatment. If people do require treatment, it may include the following:

Hair removal

In minor cases, hair removal may be the first step in treating a pilonidal sinus, if infection is not present.

Hair removal options may include:

  • shaving
  • waxing
  • laser removal
  • epilation creams

Research suggests that regular hair removal and maintaining good hygiene of the area may result in reduced surgical procedures and being able to return to normal activities. However, in some cases, hair removal increased pilonidal recurrence.

People will need to take care with certain hair removal techniques, as some may cause irritation or rashes.

Abscess drainage

If people have an abscess, a doctor will need to drain it. People can usually have this procedure at their doctor’s office.

A doctor injects a local anesthetic before making an incision into the abscess. This allows pus to drain away and reduces inflammation.

Learn more about abscess drainage and treatment options.

Pit picking

Reducing the abscess can help make the pilonidal sinus more visible and easier to treat.

A few weeks after abscess drainage, people may have a procedure called pit picking. People will have a local anesthetic and a doctor will cut out the pit, or sinus.


Antibiotics may help reduce infection and treat severe inflammation of the skin.

People may have antibiotics to treat smaller abscesses, or in addition to other treatment.


Surgery is the most reliable method for treating and removing a pilonidal sinus, but it can come with possible complications, such as poor wound healing.

People will have a general anesthetic, and a surgeon will either cut out the sinus or open it up. Completely removing the sinus by cutting it out may lead to a better outcome in the long term, but the healing period may be longer. Surgeons may use either traditional surgery with a scalpel or endoscopic surgery to open the sinus.

Learn more about the uses of endoscopic surgery.

To open, or unroof, a pilonidal sinus, a surgeon will open up the abscess and sinus, and trim any edges of the skin. A surgeon may also remove any inflamed tissue surrounding the area.

A surgeon will then use healthy tissue to close the area. This method may carry a higher risk of infection, but it may be necessary in some cases.

Surgery may take around 30 minutes, depending on the procedure.

People can discuss surgical options with their doctor to find out which may be the best choice for them, and any possible risks or side effects.

In some cases, people will not require any treatment for a pilonidal sinus and it may resolve by itself, according to ASCRS.

If people have surgery, they will usually be able to return home the same day as their operation. Depending on how people respond to surgery, they may be able to return to work within 2–3 weeks.

People can talk with a doctor about when it is safe for them to return to exercise and regular activities again.

Following treatment, it is important that people keep any wound clean and dry, or use dressings for an open wound. It is also necessary to keep the buttocks crease and wound area free from hair. People may need to keep removing hair every 2–3 weeks until they reach the age of 30, in which hair may thin out and soften.

In severe cases, a pilonidal sinus may result in complications. People may have an infection that spreads, or they may have a secondary infection.

Surgery may also lead to complications, such as:

In rare cases, pilonidal sinus may have a link to osteomyelitis, swelling or inflammation of the bone, or skin cancer.

Overall, the outlook for pilonidal sinus is very good and rarely has any long-term harmful effects.

A pilonidal sinus can return after treatment, but maintaining good hygiene habits and removing hair from the area may help reduce the risk of it returning.

A pilonidal sinus is a small tunnel under the skin above the buttocks crease. It can develop when hairs or a hair follicle get trapped deep into the skin. Inflammation and abscess formation can be painful, but treatment is usually successful.

Treatment options include abscess drainage and surgical removal of the sinus, followed by frequent hair removal to help prevent future issues.