Pilonidal sinus

Overview

A pilonidal sinus is a small tunnel or pocket that forms in the skin, usually near the tailbone (the bottom of your spine). It often contains hair and debris and can become infected, causing pain and swelling.

Yes, pilonidal sinus is a fairly common condition, particularly in young people who sit for long periods.

It mostly affects young men, but anyone can develop it. People who are overweight, have a lot of body hair, or sit for long hours at work are more at risk.

Symptoms

Common symptoms

• Pain or tenderness near the tailbone
• Swelling and redness around the area
• A small hole or dimple in the skin that may leak pus or blood
• An unpleasant smell from the discharge
• Fever if the sinus becomes infected

Symptoms in children

• Children may have the same symptoms as adults, but they might find it harder to describe the pain. Look for signs like sitting uncomfortably or complaining of a 'sore bottom'.

Symptoms in older adults

• Older adults may have milder symptoms, but the sinus can still become infected. Any new lump or pain in the tailbone area should be checked by a doctor.

Causes

Main causes

• Hair follicles in the skin become blocked, causing a small infection that turns into a sinus.
• Friction from sitting for long periods or from tight clothing can irritate the area.
• Ingrown hairs can push the infection deeper into the skin.

Risk factors

• Being a young adult (teens to 30s)
• Being male
• Having a lot of body hair
• Being overweight
• Sitting for long hours (for example, driving, desk work)
• Family history of pilonidal sinus

When to see a doctor

See a doctor urgently if:

• If you have signs of a severe infection (fever, spreading redness, severe pain)
• If the lump suddenly becomes very painful and swollen
• If you feel very unwell or have chills

Book a routine appointment if:

• If you notice a small lump or dimple near your tailbone
• If you have occasional pain or discharge from that area
• If the problem keeps coming back after treatment

Diagnosis

Doctors can usually diagnose a pilonidal sinus by looking at and feeling the area. They will ask about your symptoms and medical history.

Tests that may be done

• Usually no tests are needed – a physical exam is enough.
• If the sinus is deep or the infection is severe, your doctor may order an ultrasound or MRI scan to see how far it goes.
• Sometimes a sample of the fluid is sent to a lab to check for infection.

What to expect at your appointment

The doctor will examine the area near your tailbone. They may gently press on the lump to see if fluid comes out. The exam is not usually painful, but it may be a little uncomfortable. If you need imaging, it's painless and takes about 30 minutes.

Treatment

Treatment for pilonidal sinus depends on whether it's infected and how often it comes back. Mild cases can be managed with home care, while more serious or recurring cases may need a procedure or surgery.

Self-care at home

• Keep the area clean and dry – wash gently with mild soap and water daily.
• Apply a warm compress (a clean cloth soaked in warm water) for 10–15 minutes a few times a day to help drain the sinus.
• Avoid sitting for long periods – get up and walk around every 30 minutes.
• Wear loose, breathable underwear and avoid tight clothing.

Medical treatments

If the sinus is infected, your doctor may prescribe antibiotics (medicine to fight infection) or drain the abscess by making a small cut. For sinuses that keep coming back, surgery is often recommended to remove the sinus completely. There are different types of surgery, and your doctor will explain which is best for you.

When is surgery considered?

Surgery is usually recommended if the sinus keeps coming back, if the infection is severe, or if home care and antibiotics haven't helped. A surgeon will remove the sinus and any damaged tissue. Recovery time varies but often takes a few weeks.

Living with this condition

Living with a pilonidal sinus means paying attention to hygiene and avoiding activities that irritate the area. Most people can manage well with simple habits like keeping the area clean and taking breaks from sitting.

Lifestyle tips

• Maintain a healthy weight to reduce pressure on your tailbone.
• Avoid sitting for long stretches – stand up, stretch, or walk around regularly.
• Use a cushion or donut pillow if you have to sit for long periods.

Diet and exercise

A balanced diet with plenty of fruits, vegetables, and fiber helps you maintain a healthy weight. Regular exercise, especially activities that don't involve sitting for long, can reduce the risk of recurrence.

Mental health and emotional wellbeing

Having a pilonidal sinus can be embarrassing or frustrating, especially if it comes back. It's normal to feel worried or down. If you feel overwhelmed, talk to your doctor or a mental health professional. You can also call a crisis helpline in your area for support.

Prevention

While you can't always prevent a pilonidal sinus, you can lower your risk by keeping the area clean, avoiding long periods of sitting, and maintaining a healthy weight. Shaving the area may help some people, but it's best to talk to your doctor about what's right for you.

Vaccines

There is no vaccine for pilonidal sinus.

Screening programmes

There is no routine screening for pilonidal sinus. It is usually found when symptoms appear.

Complications

If left untreated

• The sinus may keep getting infected, leading to a painful abscess (a collection of pus).
• Infection can sometimes spread to deeper tissues or the bloodstream (very rare).
• In very rare cases, an untreated pilonidal sinus can turn into a type of skin cancer after many years.

Long-term outlook

With proper treatment, most people recover fully. Even if the sinus comes back, treatment is usually effective. The outlook is good, and most people return to their normal activities after recovery.

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