Why Ankylosing Spondylitis Flares Happen, What Helps

Medically Reviewed by Michael W. Smith, MD on November 13, 2020

Ankylosing spondylitis (AS) flare-ups can be common. Researchers and doctors don’t have an official definition of what happens in an AS flare. But if you have a flare, you know it based on how you feel.

Your flare-up may feel different than someone else’s. One study looked at flares as generalized or localized, based on whether they affected the whole body or just one area. The most common symptoms were pain, extreme tiredness, not being able to move well, and emotional changes like depression. Some also had other symptoms, such as feeling like they had the flu, sweating, and a fever. People said their joints felt hot and burning. Muscle spasms and more sensitivity also happened.

More morning stiffness may be a sign that a flare-up is coming. Sometimes, you could have stiffness and fatigue throughout the day.

Why AS Flares Happen

There are many possible causes. More inflammation is partly to blame. Other things could play a role too.

You may feel worse because of conditions you might have in addition to AS. Or you might have an injury. A weather change could even be the cause. And a flare might mean that in some way, your treatment isn’t working well enough.


When you have a flare, you may need pain medication, or you may benefit from:

Once you know what works when your AS is more intense, you can create a list so you’re ready if it happens again.

Prevention and Preparation

AS flares tend to be unpredictable. You may be able to help prevent some of them by identifying triggers such as too much stress or activity. But flares can also happen for reasons outside of your control.

Your rheumatologist can help you make a plan in case a flare happens. For instance, they can weigh in on whether to adjust how much of your medication you take during a flare and what other medications might help if you need extra help managing symptoms. Be sure to ask about:

  • What dose you should take, including the maximum amount
  • How often and how long you can use it

Take notes on what your doctor says, and make sure you can find these instructions later. When you do use medication, write down when you take it and how much you have so you can stay within the guidelines given to you. And tell your doctor about everything you take, including over-the-counter medications.

When to Call Your Doctor

Reach out to your doctor if your flare:

  • Doesn’t improve with treatment after 7 days and you need help with it
  • Is more intense or different than normal. (For example, it causes particularly strong back pain.)

You should also track your flare-ups and tell your doctor if you start to have more of them or they last longer.

WebMD Medical Reference



Oxford University Hospitals NHS Foundation Trust: “FAQ About Managing a Flare of Inflammatory Arthritis.”

National Axial Spondyloarthritis Society: “Your Flares,” “Differentiating Inflammatory and Mechanical Back Pain.”

Arthritis Foundation: “How Long Does a Flare Last?” “Enthesitis and PsA,” “What is a Flare?”

The Journal of Rheumatology: “Definition of disease flare in ankylosing spondylitis: the patients' perspective,” “Axial Spondyloarthritis Flares -- Whatever They Are.”

Mayo Clinic: “Non-Hodgkin's lymphoma,” “Uveitis.”

Clinical Rheumatology: “Spinal non-Hodgkin’s lymphoma mimicking a flare of disease in a patient with ankylosing spondylitis treated with anti-TNF agents: case report and review of the literature.”

American Psychological Association: “About APA.”

Crohn’s & Colitis Foundation: “Fact Sheet: Arthritis and Joint Pain.”

Spondylitis Association of America: “Overview of Ankylosing Spondylitis.”

© 2020 WebMD, LLC. All rights reserved.
Click to view privacy policy and trust info