SI joint belt: a low, snug band for sacroiliac pain
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- Narrow sacroiliac belt with elastic and non-elastic layers. Best for: Adults with diagnosed SI joint pain whose therapist suggests a belt. See options on Amazon
- SI belt with removable compression pads. Best for: People who want added pressure over the back of the pelvis. See options on Amazon
- Pelvic support belt for pregnancy. Best for: Pregnant people with pelvic girdle pain whose physiotherapist suggests a belt. See options on Amazon
- Knee pillow for side sleeping. Best for: SI or pelvic pain that flares when turning in bed. See options on Amazon
What the SI joints are and why they hurt
The sacroiliac (SI) joints sit where the base of the spine meets the pelvis, one on each side. Mayo Clinic says pain from these joints is usually felt in the buttocks and lower back and can spread to the legs, groin or feet. Standing or sitting for a long time, or climbing stairs, can make it worse.
Causes Mayo Clinic and Cleveland Clinic list include:
- Pregnancy. The joints loosen and stretch for childbirth, and extra weight and a changed walking pattern add stress.
- Injury, such as a fall or a car accident.
- Arthritis, including wear-and-tear osteoarthritis and inflammatory types such as ankylosing spondylitis and psoriatic arthritis.
Cleveland Clinic says some studies estimate that around one quarter of people with low back pain have sacroiliitis. Low back pain is very common, and many people feel pain near the SI joint, so a provider needs to confirm the cause before you buy anything.
How an SI belt differs from a back brace
A lumbar back brace wraps the waist and lower back. An SI belt is narrower and sits lower, across the top of the hips and the back of the pelvis. Serola, which makes a sacroiliac belt, says on its product page that its belt is worn around the hips, not the waist.
| Support | Where it sits | Usual purpose |
|---|---|---|
| SI joint belt | Low, around the hips | Hug the pelvis to steady the SI joints |
| Lumbar back brace | Waist and lower back | Support the lower spine; see our back brace guide |
| Maternity belly band or pelvic support belt | Under the bump and around the hips | Pregnancy support; see our maternity belly band guide |
Sizing and fit
Because the belt sits on the hips, you measure the hips, not your waist or pant size. Serola describes finding the spot by standing, lifting one leg and feeling where the crease forms near the hip, then measuring around the body there. Its sizes run by hip measurement:
- Small: 30 to 33 inches
- Medium: 34 to 39 inches
- Large: 40 to 45 inches
- X-Large: 46 to 52 inches
Other makers size differently, so always use the chart for the belt you are buying.
On tightness, Serola says the right tension is about what you would use to tie a shoe, and that too much or too little tension can cause muscle spasm. It also says the belt should not cause discomfort and should be stopped if it does. Tighter is not better.
Where a belt fits in treatment
Cleveland Clinic names physical therapy as the most common treatment, with exercises that strengthen the muscles around the SI joints and improve range of motion. Other options it lists include anti-inflammatory medicines, muscle relaxers, steroid injections and, less often, radiofrequency ablation or surgery. It advises not taking NSAIDs for more than 10 days in a row without talking to your provider.
A belt is a support, not a fix. In pregnancy, the NHS says a physiotherapist may recommend a pelvic support belt to help ease pelvic girdle pain. Outside pregnancy, ask your physical therapist whether a belt fits your plan and how long to wear it each day.
Simple habits help too. For pregnancy-related pelvic pain, the NHS suggests sleeping with a pillow between your legs, avoiding long periods of sitting or standing, and avoiding heavy lifting.
Common mistakes
- Wearing it at the waist. An SI belt that rides up onto the waist is no longer around the pelvis.
- Cranking it tight. A shoe-lace level of snugness is the maker's guide; numbness, tingling or pain means loosen it or stop.
- Skipping the diagnosis. Pain near the SI joint is common with many kinds of low back pain, and Cleveland Clinic lists inflammatory causes such as ankylosing spondylitis that need a provider's care.
- Using it instead of exercise. Strengthening work from a therapist is the main treatment Cleveland Clinic describes.
What to look for when you buy
Narrow sacroiliac belt with elastic and non-elastic layers
Best for: Adults with diagnosed SI joint pain whose therapist suggests a belt
Serola describes its belt as having a non-elastic layer that gives a stop point at the end of normal motion and an elastic layer for compression. This narrow, hip-level design matches the job of hugging the pelvis rather than the waist.
Watch out: Sized by hip measurement, not waist. Hand wash only, per the maker, and stop if it causes discomfort.
See options on AmazonSI belt with removable compression pads
Best for: People who want added pressure over the back of the pelvis
Pads sit over the SI area on each side and add local pressure on top of the band. Removable pads let you test the belt with and without them.
Watch out: Pads can press too hard if the belt is over-tightened. Check your skin after the first few wears.
See options on AmazonPelvic support belt for pregnancy
Best for: Pregnant people with pelvic girdle pain whose physiotherapist suggests a belt
The NHS says a physiotherapist may recommend a pelvic support belt to help ease pelvic girdle pain in pregnancy. Look for one that sits low around the hips rather than over the bump.
Watch out: Get pelvic pain checked by your midwife or doctor first. A belt does not replace physiotherapy.
See options on AmazonKnee pillow for side sleeping
Best for: SI or pelvic pain that flares when turning in bed
For pregnancy pelvic pain, the NHS suggests a pillow between your legs for extra support in bed. A shaped knee pillow stays in place more easily than a bed pillow.
Watch out: It eases position, it does not support the joint during the day.
See options on AmazonQuestions people ask
- Where should an SI belt be worn?
- Low around the hips, not the waist. Serola says its belt is worn around the hips and that the area to measure is where the crease forms when you lift your leg.
- How tight should an SI joint belt be?
- Snug, not crushing. Serola compares the right tension to tying a shoe and says too much or too little can cause muscle spasm. Loosen it if you feel numbness or pain.
- Do SI belts really work?
- The medical sources here do not report a study of belts for SI pain. The NHS says a physiotherapist may suggest a pelvic support belt in pregnancy, and Cleveland Clinic names physical therapy as the most common treatment, so think of a belt as support during that work, not the treatment itself.
- Can I wear a sacroiliac belt while pregnant?
- The NHS says a physiotherapist may recommend a pelvic support belt for pelvic girdle pain in pregnancy. Ask your midwife or physiotherapist which type and fit is right for you.
- When should I see a doctor for SI joint pain?
- Cleveland Clinic advises seeing a provider for new or worsening low back pain, pain that does not get better on its own in a week, or treatments that stop working.
Sources
- Sacroiliitis: Causes, Symptoms & Treatment Options (my.clevelandclinic.org), Cleveland Clinic
- Sacroiliitis: Symptoms and causes (mayoclinic.org), Mayo Clinic
- Pelvic pain in pregnancy (nhs.uk), NHS
- Serola Sacroiliac Belt (serola.net), Serola Biomechanics