Sacroiliitis vs. Lower Back Pain: How to Tell the Difference
February 18, 2026
Lower back pain is a common complaint, but not all back pain is the same. Two conditions often confused with one another are general lower back pain and sacroiliitis, an inflammation of the sacroiliac (SI) joints. Understanding the differences between them can help you get the right diagnosis and treatment.
What Is Sacroiliitis?
Sacroiliitis occurs when one or both of the sacroiliac joints—located where the lower spine meets the pelvis—become inflamed. These joints are critical for stabilizing the pelvis and transferring weight between the upper body and legs. Inflammation in this area can cause pain, stiffness, and difficulty with movement.
Common causes include:
- Arthritis (such as ankylosing spondylitis)
- Injury or trauma to the lower back or pelvis
- Pregnancy, which puts extra stress on the SI joints
- Infection or inflammatory conditions
Symptoms of Sacroiliitis vs. General Lower Back Pain
| Symptom | Sacroiliitis | General Lower Back Pain |
|---|---|---|
| Pain location | Often in the buttocks, lower back, or radiating into the legs | Central lower back, sometimes spreading to hips |
| Pain type | Sharp, stabbing, or deep aching | Dull, aching, or sore |
| Aggravating activities | Standing up from sitting, climbing stairs, running | Lifting, bending, prolonged sitting |
| Relief | Rest, certain stretches, anti-inflammatory treatments | Rest, heat, general physical therapy |
How Doctors Diagnose the Difference
Diagnosing sacroiliitis versus general lower back pain usually involves a combination of:
- Medical history and physical exam – Doctors will assess pain patterns and movements that worsen symptoms.
- Imaging tests – X-rays, MRI, or CT scans can show inflammation or structural changes in the SI joints.
- Diagnostic injections – In some cases, a doctor may inject a local anesthetic into the SI joint to see if it relieves pain, confirming the source.
Treatment Options
Treatment depends on the underlying cause but may include:
- Non-surgical approaches: Physical therapy, anti-inflammatory medications, activity modification
- Interventional procedures: Corticosteroid injections, radiofrequency ablation for pain relief
- Surgery: Rarely needed, usually reserved for severe, persistent cases
Key Takeaways
- Sacroiliitis is inflammation of the SI joints and can mimic general lower back pain.
- Location, type, and triggers of pain often help distinguish the two.
- Early diagnosis can prevent chronic pain and improve mobility.
If you’re experiencing lower back pain, particularly pain radiating to your buttocks or legs, consult a healthcare provider for an accurate diagnosis. Proper treatment can make a significant difference in your quality of life.