Symptoms of an AS flare-up can include fatigue, back stiffness, fever, depression, and joint pain. To treat an AS flare-up, a person can try medication, gentle exercise, and heat or cold therapy. They can also use a transcutaneous electrical nerve stimulation (TENS) machine.

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A person living with AS may experience frequent flare-ups throughout their life. Research from 2017 states that people may experience three flare-ups in 3 months, each lasting for up to 2 weeks.

There are two main types of AS flare-ups: generalized and localized.

Generalized AS flare-ups tend to be worse than localized AS flare-ups. They may cause burning pain in several joints of the body. In addition, a person will likely experience additional flu-like symptoms, tenderness, and muscle spasms.

Localized AS flare-ups affect only one part of the body. The symptoms can include immobility, pain, and fatigue.

This article reviews the common symptoms associated with AS flare-ups. It also looks at the treatment options available and how a person can help prevent flare-ups from occurring.

People living with AS may experience different symptoms during a flare-up. Some common symptoms include the following:


Fatigue can be a sign of a flare-up and ongoing disease activity.

Some experts believe that fatigue occurs due to systemic inflammation. The body has to use energy to reduce the inflammation, which then leaves a person feeling drained and having low energy.

Other related causes of fatigue include pain, depression, and other factors that disrupt sleep.

Back stiffness and pain

AS flare-ups often come with an increase in back pain and stiffness. Pain can make resting and sleeping difficult or impossible for long periods of time.

Uncontrolled pain can lead to fatigue when a person is unable to get enough sleep each night.


According to Creaky Joints, fever can be a symptom of a flare-up or the result of an infection. A person who develops a fever should speak with a doctor.

People who take certain medications, such as biologics, have a higher risk of developing an infection. They should report any fever to a doctor so the doctor can check for the presence of an infection.


As many as 75% of people experience emotional symptoms during an AS flare-up, such as depression. This may be due to the physical and mental strain that pain and stiffness can put on a person.

In addition, a 2020 review found that people living with AS have an increased risk of developing depression or anxiety. They noted that people with AS should talk with a medical professional about monitoring and care for any psychiatric conditions.

Pain in other joints

During a flare-up, a person may experience pain in joints beyond their lower back and pelvic region. Some people may have enthesitis, which is inflammation and stiffness where tendons meet bones.

A person may experience pain in their:

  • ankles
  • knees
  • rib cage
  • neck

Many of the short-term symptoms of a flare-up can continue for a while after the flare-up. A person can also experience symptoms related to chronic inflammation from uncontrolled AS.

Long-term symptoms of a flare-up can include:

  • continuing back pain
  • stiffness and pain in other joints
  • difficulty moving and with flexibility
  • uveitis, which is the inflammation of the middle layer of the eye
  • gastrointestinal (GI) issues
  • difficulty breathing
  • fatigue
  • jaw pain and stiffness

Continuing back pain

Continuing or chronic lower back pain can come and go over time.

During a flare-up, the pain and stiffness can spike. After a flare-up, it may ease or go away entirely. However, it will eventually return.

Stiffness and pain in other joints

Though AS typically affects the spine in the lower back and the pelvic region, it can also affect other joints.

The pain often gets worse during periods of inactivity, such as overnight or during a long stretch of sitting.

Trouble moving and with flexibility

The chronic inflammation associated with AS can cause damage to joints throughout the body. This can limit a person’s ability to move and their overall flexibility.

Some people may also develop new bone growth in their spine that fuses portions together, further limiting their movement and flexibility.

Inflammation in the eyes

Up to 30% of people living with AS develop uveitis, a condition that affects the middle layer of the eye. The condition can cause pain, sensitivity to light, and redness in the eyes.

GI issues

About 10% of people living with AS develop inflammatory bowel disease (IBD). The two conditions share some genetic links.

However, even people who do not develop IBD have a chance of developing GI symptoms such as diarrhea, bloating, and other symptoms.

Trouble breathing

People living with AS may develop chest pain and trouble breathing.

The inflammation can affect the rib cage and make it stiffer. When this occurs, it can make breathing deeply painful or uncomfortable.


Inflammation can cause fatigue over time.

The body needs to use energy to manage excess inflammation. This means a person has less energy overall and will not feel regenerated even if they get the recommended hours of sleep each night.

Jaw pain and stiffness

About 15% of people living with AS develop inflammation in the mouth and jaw. When it affects the jaw, a person may have trouble fully opening their mouth during activities such as eating.

Just as symptoms a person experiences during an AS flare-up can differ, so can the time they last.

Some estimate that people living with AS experience approximately three flare-ups in 3 months. These can last up to 2 weeks at a time.

A person should work with a healthcare professional to determine the best treatment for them.

They should also consider contacting a doctor if they experience symptoms such as fever that could indicate an underlying illness.

Medications, including nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, are the first-line treatment. A doctor may prescribe biologics if NSAIDs do not work.

Other common treatment methods for a flare-up include:

TENS help to block nerves from transmitting pain signals to the brain.

Learn more about the effects of ankylosing spondylitis on the body and how to treat them.

Experts do not fully understand the exact causes of AS flare-ups.

Some anecdotal information suggests that possible causes could include stress, both physical and emotional, and overexertion. Excessive fatigue can also trigger AS flare-ups.

A person living with AS may not be able to prevent all flare-ups.

Some steps they can take to help prevent flare-ups, or to cope with them, include:

  • taking steps to manage mental health, such as anxiety and depression
  • making plans for how to cope with a flare-up when they arise
  • taking time to rest during daily routines
  • following all treatment recommendations
  • getting regular exercise and eating a balanced, nutritious diet

AS flare-ups can cause a variety of symptoms when they first occur. They can also persist for a period of time after.

Flare-ups can involve both physical symptoms, such as pain in the lower back and fatigue, as well as mental health symptoms, such as depression or anxiety.

Doctors may recommend a combination of medication and therapies to help a person treat a flare-up. A person may be able to reduce their chance of having a flare-up by taking steps to manage their condition, stress levels, and fatigue.