An anal abscess, also known as a perianal or rectal abscess, occurs when a cavity in the anus becomes filled with pus. Symptoms may include pain, constipation, or fever. Treatment may include drainage of the abscess or surgery.

A perianal abscess occurs when a cavity in the anus becomes filled with pus. The terms “anal abscess” and “rectal abscess” can also be used to describe this same condition.

Anal abscesses can cause:

In some cases, they can result in painful anal fistulas. This occurs when the abscess breaks open on the surface of the skin. If an anal abscess isn’t drained, it can cause a lot of pain and may require surgery.

A rectal abscess can happen when a tear in that area becomes infected or an anal gland becomes blocked. A sexually transmitted infection (STI) can also cause anal abscesses.

Toddlers or children that have a history of anal fissures (tears in the anal sphincter) are also at a higher risk for developing anal abscesses later on. Such anal fissures might occur in children who have a history of constipation.

Anal abscesses are twice as likely in males compared with females.

Some other risk factors include:

This condition is likely underdiagnosed, as many people may not seek medical attention because they believe they may be experiencing hemorrhoids. It’s important to make an appointment with a doctor if you believe you have a perianal abscess.

If left untreated, anal abscesses can lead to severe complications, such as:

  • an anal fistula, an atypical opening in the skin near the anus
  • sepsis, a life threatening condition due to your body’s response to an infection
  • Fournier’s gangrene, a rare but potentially life threatening infection

Throbbing and constant pain in the anal area can be one of the most common and immediately noticeable symptoms of an anal abscess. The pain is usually accompanied by swelling in the anal area and greater pain during bowel movements.

Common signs of an anal abscess include:

  • constant pain that can be dull, sharp, throbbing, or aching
  • constipation
  • rectal discharge or bleeding
  • swelling or tenderness of the skin surrounding the anus
  • fatigue
  • fever
  • chills

Some people may be able to feel a nodule or lump that’s red, swollen, and tender at the rim of the anus. Fever and chills can result from the infection. You may also have rectal bleeding or urinary symptoms, such as difficulty urinating.

Anal abscesses may also occur deeper in the rectum, most often in those who have inflammatory bowel diseases. This can result in some pain or discomfort in the abdominal area.

In toddlers, there typically aren’t many symptoms other than signs of discomfort or pain, which may cause a child to become irritable. A lump or nodule may also be visible or felt around the anal area.

Anal abscesses are most often diagnosed through a physical exam where a doctor checks the area for characteristic nodules. The doctor may also check for pain, redness, and swelling in the anal area and rule out other conditions.

In some people, there may not be any visible signs of the abscess on the surface of the skin around their anus. The doctor will instead use an instrument called an anoscope to look inside the anal canal and lower rectum.

Sometimes, the abscess may be deeper than a physical exam can find. The doctor may order imaging tests, such as a CT scan, MRI, or ultrasound, to get a better look.

Further tests may be necessary to make sure Crohn’s disease isn’t a contributing factor.

In these cases, blood and stool tests, imaging, and a colonoscopy may be needed. A colonoscopy is an outpatient procedure in which a doctor uses a flexible scope with a light to examine the colon and large intestine.

Anal abscesses rarely go away without treatment from a doctor. Treatment may include drainage or surgery.

The most common and simple treatment is for a doctor to drain the pus from the infected area.

This can usually be done in the doctor’s office. The doctor will use medication to numb the area. Any uncomfortable pressure should be relieved, allowing the tissue to begin healing properly.

If there’s an extremely large anal abscess, surgery with anesthesia may be required. In some cases, a catheter may be used to make sure the abscess drains completely. Abscesses that have been drained are typically left open and don’t require stitches.

If you have diabetes or a weakened immune system, your doctor may ask you to stay in the hospital for a few days to watch for any infection.

Treatment following drainage may include:

  • Medication. The doctor may prescribe antibiotics if you have a weakened immune system or if the infection has spread. Antibiotics are not considered sufficient to treat the infection on their own but may be prescribed after draining the abscess.
  • Laxatives or fiber supplements. As you heal after draining the abscess, your doctor may recommend laxatives or fiber supplements to avoid constipation.
  • Warm baths. After this procedure, the doctor may provide guidance on how to keep the area clean and may recommend a sitz bath. It’s recommended you take warm (not hot) baths. Sitting in warm water may help reduce swelling.
  • Follow-up appointments. Because there is a chance for anal abscesses to recur or fistulas to develop, it’s important to attend all follow-up appointments. A 2019 study found that having a higher body mass index (BMI) may be correlated with abscesses recurring.

The recovery period for a drained rectal abscess is about 3 to 4 weeks.

If anal abscesses are left untreated, they can turn into painful anal fistulas that may require more surgical treatment.

According to the American Society of Colon and Rectal Surgeons, about 50 percent of people who have an anal abscess will eventually develop an anal fistula. A fistula generally requires surgery.

There isn’t much known about how to prevent an anal abscess. But there are some steps you can take, including:

  • taking measures to protect yourself from STIs and seeking prompt treatment
  • using condoms or other barrier methods, especially during anal sex, to help prevent STIs that may cause anal abscesses
  • practicing good hygiene and cleanliness in the anal area
  • treating conditions like Crohn’s disease that may cause anal abscesses

Anal abscesses can cause complications, but they’re treatable. It’s important to understand the risk factors and closely monitor and manage any health conditions that may increase risk.

If you notice anal problems, contact a doctor to get treatment and to prevent them from becoming worse.