Sacroiliitis is a painful condition where either one or both of the sacroiliac joints become inflamed. The sacroiliac joints are found where the spine meets the pelvis.

Often misdiagnosed as lower back pain, sacroiliitis is related to diseases that cause inflammatory arthritis in the spine.

Sacroiliitis may cause pain in the buttocks, lower back, and down one or both legs. This article looks at the causes, symptoms, and treatments for sacroiliitis.

Causes of sacroiliitis

Doctor pointing to sacroiliac joints in model of pelvic bones.
Sacroiliitis is the inflammation of the sacroiliac joints, which connect the pelvis to the spine.

There are several potential causes for inflammation in the sacroiliac joints. These include:

  • Ankylosing spondylitis: This is a progressive type of inflammatory arthritis that affects the spine and hips. As this 2005 report explains, sacroiliitis is an early sign of this condition. Not all people who experience sacroiliitis have ankylosing spondylitis.
  • Osteoarthritis: This can cause inflammation in the sacroiliac joints and is another underlying cause of sacroiliitis.
  • Trauma: A sudden traumatic injury may damage the sacroiliac joints and cause inflammation, leading to sacroiliitis.
  • Pregnancy: When a woman is pregnant, her sacroiliac joints stretch to make room for the growing baby. This may put stress on the joints and cause sacroiliitis.
  • Infection: If the sacroiliac joint becomes infected it can become inflamed.

In addition, the following conditions may make it more likely for a person to develop sacroiliitis:

Sacroiliitis symptoms

Lower back and pelvis pain, in person sitting down holding their hips.
Common symptoms of sacroiliitis include stiffness and pain in the lower back and buttocks.

The main symptoms of sacroiliitis include:

  • pain in the buttocks, lower back, and back of one or both legs
  • slight fever
  • stiffness in the hips and lower back

Sometimes sacroiliitis can cause pain in the hips and feet too, although this is less common.

The following activities can aggravate sacroiliitis pain:

  • sitting or standing for long periods
  • standing with the weight on one leg
  • climbing the stairs
  • taking long strides when walking
  • running
  • turning over in bed


Sacroiliitis may be hard to diagnose, as it can be mistaken for lower back pain caused by a different condition, such as sciatica.

A doctor may press on the hip and buttock or move a person’s legs to examine the sacroiliac joints.

To determine whether the pain is coming from the sacroiliac joint, the doctor may inject a numbing solution into the joint.

Further screening may be needed if the doctor is unsure of the diagnosis. A 2013 report highlighted the importance of MRI tests as a diagnostic tool for sacroiliitis.

Research conducted in 2013 found a type of screening called computed tomography may also be useful in diagnosing sacroiliitis.


There are a variety of treatments available for sacroiliitis. These include medications, exercises, and surgical procedures.


Bottle of pain killer medication, with pile of pills in the foreground.
Over-the-counter pain relievers may help to treat mild symptoms of sacroiliitis.

The following medications can help to treat sacroiliitis:

  • Pain relievers: Over-the-counter pain medications may provide some relief. The doctor may prescribe stronger medicines if over-the-counter options are not helping.
  • Muscle relaxants: Sacroiliitis can cause muscle spasms that may be painful. Muscle relaxants can help relieve these.
  • TNF inhibitors: This type of medication can help ease sacroiliitis if it is associated with ankylosing spondylitis. A 2016 study showed that TNF inhibitors could significantly improve both activity and joint function.

Home remedies and exercise

As well as prescribed medications, the following home remedies and exercises can help relieve sacroiliitis pain:

  • Rest: Avoiding the movements that aggravate sacroiliitis pain can help to reduce inflammation.
  • Ice and heat: Alternating placing ice and heat packs on the affected area may help relieve sacroiliitis pain. A person should always cover ice and heat packs with a towel to prevent burns and damage to the skin.
  • Hip flexion exercises: This exercise involves laying on the back with the legs supported by a box or pillows. Cross one leg over the other, squeeze the legs together and then release. Repeat this on both sides. Try a variation of this exercise by laying on the back, lifting the legs, and then squeezing them together with a pillow in between.

Surgery and other procedures

In severe cases where medication and exercise do not relieve sacroiliitis pain, the doctor may recommend one of the following surgeries or procedures:

  • Electrical stimulation: An electrical stimulator can be implanted into the sacrum, which may help to reduce the pain.
  • Joint injections: Injected corticosteroids into the sacroiliac joint can help to reduce inflammation and pain. Having too many injections may cause other problems, so they are usually limited to 2 to 4 per year.
  • Radiofrequency denervation: This type of treatment works on the nerve tissue that may be causing sacroiliac pain.
  • Joint fusion: In severe cases, fusing the two bones together with a metal plate or other fusion devices may help relieve sacroiliitis pain.


There is a range of treatments available for sacroiliitis that can relieve the pain associated with the condition.

Long-term improvement will depend on the cause of the condition. Joint damage and degenerative forms of arthritis will need ongoing treatment to manage symptoms.

A doctor can recommend the best way to manage sacroiliitis symptoms and relieve pain associated with the condition.