Sacroiliitis happens when something irritates the joint where your spine meets your pelvis. Arthritis is the most common cause, especially ankylosing spondylitis. Typical reatments are physical therapy and over-the-counter pain medication.


The sacrum, ilium and sacroiliac joints.
Inflammation of one or both of your sacroiliac joints.

What is sacroiliitis?

Sacroiliitis is painful inflammation in the joints where your spine connects to your pelvis (your sacroiliac joints). It causes pain in your lower back, butt (your buttock muscles) or legs.

A joint is a place in your body where two bones meet. Your sacroiliac joints are the connection between your spine and pelvis. Specifically, they’re the place where the sacrum (the triangle-shaped last section of your spine) meets the ilium (the top part of your pelvis).

The sacroiliac joints are some of the biggest joints in your body, and you use them every time you move or shift your hips. Sacroiliitis happens when something irritates or damages one or both of your sacroiliac joints. This irritation leads to inflammation, which causes pain that you’ll usually feel in your low back and butt.

Visit a healthcare provider if you’re experiencing low back pain. It’s a common symptom that can be caused by a lot of issues. The sooner a provider diagnoses what’s causing your discomfort, the faster you can treat it and reduce its impact on your daily routine.

Types of sacroiliitis

A healthcare provider might refer to sacroiliitis with different names depending on how many of your sacroiliac joints are affected. Unilateral sacroiliitis is sacroiliitis that affects one of your joints. Bilateral sacroiliitis is having sacroiliitis in both joints at the same time.

How common is sacroiliitis?

It’s hard for experts to estimate how many people have sacroiliitis every year because low back pain is such a common symptom and can be caused by so many conditions. Some studies estimate that around one-quarter of people with low back pain have sacroiliitis.


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Symptoms and Causes

What are sacroiliitis symptoms?

Pain in your lower back is the most common sacroiliitis symptom. The pain might:

  • Get worse after you’ve been sitting or standing in one position for a long time.
  • Get worse when you turn or rotate your hips.
  • Feel suddenly sharp and stabbing. You might also feel a more constant dull ache.
  • Radiate (spread) from your low back into your butt (your buttock muscles), hips or thighs.

People with sacroiliitis often feel stiff first thing in the morning. It’s common to have some stiffness after sleeping or sitting in one position, but the stiffness sacroiliitis causes usually lasts for more than an hour every time you wake up.

What causes sacroiliitis?

Anything that causes inflammation in your joints can affect your sacroiliitis joints and cause sacroiliitis. Arthritis is the main cause of sacroiliitis, including:

  • Ankylosing spondylitis: Ankylosing spondylitis is arthritis that affects the joints in your spine. Sacroiliitis is often an early symptom of ankylosing spondylitis.
  • Psoriatic arthritis: Psoriatic arthritis is a combination of psoriasis and arthritis. It causes arthritis symptoms in your joints and psoriasis (scaly, flaky patches) on your skin.

Other health conditions that cause inflammation can cause sacroiliitis too, including:

People sometimes experience sacroiliitis during pregnancy. Hormones that cause your body to change while you’re pregnant can make your sacroiliac joints widen and rotate.

A rare bacterial infection (Staphylococcus aureus) can cause sacroiliitis if the infection attacks your sacroiliac joints.


What are complications of sacroiliitis?

If it’s not treated soon enough, the pain from sacroiliitis can affect your ability to move. Untreated pain can also disrupt your sleep and lead to mental health conditions like depression.

Diagnosis and Tests

How is sacroiliitis diagnosed?

A healthcare provider will diagnose sacroiliitis with a physical exam and some imaging tests. They’ll examine your back, hips and legs. Tell your provider when you first noticed pain or other symptoms and if certain activities make the pain worse. Talk to your provider about other health conditions or issues you have. This can help them determine what’s causing the sacroiliitis.

Your provider might have you perform some physical movements to check your range of motion (how far you can move a part of your body without feeling pain). They might press on your sacroiliac joints or the area around them. Tell your provider if any position, movement or type of pressure makes the pain worse.

What tests will providers use to diagnose sacroiliitis?

Your provider might use imaging tests to take pictures of your sacroiliac joints, including:

Your provider might also use blood tests to rule out infections and other issues that cause inflammation in your body.


Management and Treatment

How is sacroiliitis treated?

Physical therapy is the most common treatment for sacroiliitis. A physical therapist will give you stretches and exercises to strengthen the muscles around your sacroiliac joints. This will take pressure off your joints and help keep them more stable. Doing exercises for sacroiliitis will also help you increase your range of motion in your sacroiliac joints.

Your healthcare provider might also suggest you manage pain with medications, including:

  • NSAIDs: Over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) are medications like aspirin, ibuprofen or naproxen. Don’t take NSAIDs for more than 10 days in a row without talking to your provider.
  • Muscle relaxers: Muscle relaxers (muscle relaxants) are prescription medications that treat muscle pain by preventing your nerves from sending pain signals to your brain.
  • Corticosteroids: Corticosteroids are prescription medications that relieve pain and inflammation. Your provider might inject a corticosteroid directly into your affected joint.

It’s less common, but your provider might suggest a radiofrequency ablation (RFA) to permanently block nerves in your joint from sending pain signals to your brain.

You might need to work with a rheumatologist, a specialist who treats inflammatory diseases.

Sacroiliitis surgery

It’s rare to need surgery for sacroiliitis. Your provider might recommend surgery if physical therapy and other treatments like RFA haven’t improved your pain.

Your surgeon might perform a joint fusion — permanently fastening the joint together with surgical screws. They’ll tell you which procedure you’ll need and what to expect while you’re recovering.


Can I prevent sacroiliitis?

There’s usually no way to prevent sacroiliitis.

You can lower your chances of developing arthritis by:

  • Avoiding tobacco products.
  • Doing low-impact exercise.
  • Following a diet and exercise plan that’s healthy for you.

Outlook / Prognosis

Is sacroiliitis permanent?

If you have inflammatory arthritis, the damage in your affected joints might be permanent. Pregnant people who experience sacroiliitis usually only have it while they’re pregnant.

Most people with sacroiliitis can treat the cause with medication and manage their symptoms with physical therapy. Talk to your provider if your symptoms come back (recur) or get worse.

Living With

When should I see my healthcare provider?

Visit a healthcare provider if you’re experiencing new or worsening pain in your low back. Talk to your provider if it feels like your pain is getting worse or your sacroiliitis treatments aren’t as effective as they used to be.

What questions should I ask my healthcare provider?

  • Do I have sacroiliitis, sacroiliac joint point or another cause of lower back pain?
  • Do I have arthritis? Which type?
  • Will I need physical therapy?
  • Which medications will I need?
  • Will I need surgery?

Additional Common Questions

Is sacroiliitis the same as sacroiliac joint pain?

It’s possible to have pain in or near your sacroiliac joint without having sacroiliitis. Low back pain is extremely common, and many people feel pain near their sacroiliac joint.

The difference is sacroiliitis is joint inflammation that a healthcare provider diagnoses. Visit a provider if you’re experiencing pain that doesn’t get better on its own in a week. They’ll help you understand what’s causing the pain and how you can avoid it in the future.

A note from Cleveland Clinic

Sacroiliitis is inflammation at the joint where your spine meets your pelvis, which causes low back pain. Any pain is annoying, especially when it makes it hard to move and use your body the way you usually can. The good news is that no matter what’s causing your pain, a healthcare provider will help you find ways to manage your symptoms, like physical therapy. And while physical therapy is hard work, don’t forget to celebrate your successes and take time to give yourself credit for the progress you’re making.

Medically Reviewed

Last reviewed on 08/23/2023.

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