Ankylosing spondylitis (AS) is a type of autoimmune disease. This means that the immune system attacks healthy cells in the body. In the case of AS, the immune system attacks the joints, which leads to pain and other symptoms. It also may cause joint damage.

AS is a form of inflammatory, chronic arthritis. It most commonly affects a person’s spine and the sacroiliac joints, which connect the lower spine to the hip bones. The condition can cause stiffness, inflammation, and pain in the affected joints.

Although there is no cure for AS, treatments and lifestyle changes can reduce the severity of the symptoms and slow the progression of the disease, helping avoid joint damage.

This article explains what causes pain in people with AS and how it feels. It also discusses some common treatment options for people living with the condition.

AS causes symptoms that can vary from person to person. The most common symptoms of AS include pain and stiffness in the lower back and hips.

People often notice that their symptoms worsen after periods of inactivity, such as sleeping. Getting up in the morning after lying prone for hours may be uncomfortable.

The pain associated with AS can feel like a general ache across a person’s body rather than a localized pain in the joints. It can also affect one side of the body or alternate between the sides.

According to the Global Healthy Living Foundation, people often describe the pain as a dull, persistent pain that feels as though it originates from deep inside the buttocks or lower back. Additionally, they may experience:

  • symptoms that worsen and then get better at regular intervals
  • morning stiffness
  • waking in the middle of the night in pain
  • fatigue
  • limited mobility in the spine
  • mild fever
  • loss of appetite

In some cases, AS can make it more difficult for a person to breathe if chest expansion results in significant discomfort.

In addition, a person may experience other complications and symptoms. These can include:

  • inflammatory bowel disease (IBD)
  • issues with the eyes that can affect vision
  • depression
  • anxiety

Researchers do not currently know what causes AS. It may be related to genetic factors, but it does not pass directly from parent to child. It is also not contagious.

A common cause of worsening AS symptoms is rest or inactivity. Many people report stiffness and pain in the morning upon waking up. Pain and stiffness often go away on their own after a person has started moving.

AS is similar to another condition called rheumatoid arthritis. As a result, some of the triggers of RA may affect a person living with AS. According to the Arthritis Foundation, some potential triggers of worsening symptoms due to inflammation include:

  • infection
  • poor sleep
  • stress
  • overexertion

Researchers advise that individualized treatment for AS is the best approach. Treatment typically focuses on:

  • slowing the progression of the disease
  • preventing joint damage and further complications
  • alleviating stiffness, pain, and discomfort

Some common treatments may include one or more of the following therapies:

  • Nonsteroidal anti-inflammatory drugs (NSAIDs): NSAIDs, such as ibuprofen and aspirin, can help reduce inflammation and pain associated with AS. A doctor may prescribe stronger versions of these medications.
  • Disease-modifying antirheumatic drugs (DMARDs): DMARDs are prescription medications that reduce inflammation. By doing so, they can help prevent joint damage and reduce symptom severity.
  • Biologics: Biologics are not suitable for everyone, but they can help with reducing inflammation.
  • Physical therapies: Physical therapy, occupational therapy, and other therapies can help restore movement and keep a person safely active.
  • Steroids: Doctors may recommend the use of steroids for the short-term treatment of flares. They are available in the form of ointments for the eyes, oral pills, or an injection.
  • Surgery: Although many people living with AS will not need surgery, a doctor may recommend it to restore range of motion to a joint or fix damaged joints.

In addition to medical treatments, a person can take steps at home to help reduce symptom severity. Some lifestyle adjustments that may help include:

  • Staying active: Maintaining a regular exercise routine — whether it involves playing sports, doing physical therapy, or engaging in other activities that require movement — may help control symptoms. A person should talk with a doctor about what exercises are safe and how to go about beginning a new exercise routine to prevent injury.
  • Eating a balanced diet: Along with exercise, a nutritious diet can help prevent the symptoms of AS that result from inflammation. Some suggestions include avoiding processed meats and foods while eating a variety of fruits and vegetables and plenty of fiber, whole grains, lean protein, and healthy fats.
  • Maintaining a moderate weight: Being overweight or underweight can lead to various health issues, which can affect overall health as well as AS symptoms. A person should talk with their doctor about their ideal weight and ways to stay within the recommended range.
  • Avoiding alcohol: Alcohol intake, particularly heavy consumption, can worsen symptoms.
  • Increase calcium intake: A sufficient intake of calcium and vitamin D is important for maintaining bone health. A doctor can offer an individual advice on whether taking supplements, making dietary changes, or doing both is the best course of action.

Ankylosing spondylitis often causes a dull ache that originates from the lower back or buttocks. As well as causing pain, the condition can lead to a range of complications, including eye problems and IBD.

A person can often manage their AS symptoms with a combination of lifestyle adjustments, medications, and therapies. A person should work with a doctor to find a treatment plan that works for them.