Sciatica on One Side? Why Your Hip Flexor May Be Involved

Sciatica usually picks a side. The pain runs down one leg or sits in one side of the low back while the other side feels normal. Sometimes the source is the spine. But much of what gets called sciatica starts in the muscles, which can pull the pelvis out of alignment and irritate the sciatic nerve.

Why does sciatica only hurt on one side?

Sciatica usually hurts on one side because the problem behind it is often one-sided. A bulging disc tends to press toward one side, and muscles rarely hold the same tension on both sides. The side holding more is often the one that hurts. Habits and history decide which side. A dominant stance leg, an old ankle sprain, a repetitive sport, the way you sit at a desk, or the foot you drive with can all load one side more than the other.

The piriformis is one of the muscles most often involved in sciatica, because the sciatic nerve runs right beneath it, and in some people, straight through it. It's a small stabilizer deep in the hip. When it's overworked and holding tension, it's usually compensating. Most often it's covering for a glute max that isn't doing its share of steadying the hip and pelvis with each step.

So why isn't the glute doing its job, and what's holding it back?

How can a tight hip flexor lead to sciatica?

A tight hip flexor, the iliacus in particular, is often what's holding the glute back. The iliacus lines the inside of the pelvis and attaches to the top of the thigh bone. When one side holds more tension, it rotates that half of the pelvis forward.¹

That tilt keeps the front of the hip slightly shortened. The hip flexors and the glute max sit on opposite sides of the hip, and when one side stays switched on, the nervous system turns the other side down. That's called reciprocal inhibition. The glute can't fully extend the hip, so it feels weak. Your glute isn't dead. Your iliacus is just holding it hostage.

With the glute turned down, the piriformis keeps picking up the slack, and that's where the sciatic nerve can get irritated. The glute minimus, another small stabilizer nearby, often overworks too. Its referred pain runs down the back and side of the leg in a pattern that closely mimics sciatica.³

Meanwhile, the same tilt adds load through the SI joint and low back on that side. That's how the pain can run up into the back and down the leg at the same time.

How can you tell if sciatica is coming from your spine or your muscles?

Only an exam can confirm it, but the pattern of your symptoms gives you good clues.

The columns overlap more than a table suggests. A tense piriformis can irritate the sciatic nerve directly, so numbness or tingling doesn't rule out the muscles. A disc problem can also come with muscle tension on top of it.

If your symptoms have been blamed on the spine and aren't improving, it's worth looking at the hip flexor side too. In one case series, six patients with leg symptoms attributed to the lumbar spine improved after trigger point dry needling and stretching of the iliopsoas.²

READ MORE: 3 Places the Sciatic Nerve Gets Pinched

How do you release the muscles causing sciatica?

Work in order: release, realign, reactivate. Release the iliacus before the piriformis. The piriformis is often overworking because the iliacus is holding the glute back, so releasing the iliacus first takes away the reason it's working so hard.

Release. Hold prolonged pressure for about 90 seconds per side on the psoas, then the iliacus, then the piriformis. Start light. More pressure isn't more effective.

Realign. Once the piriformis has released, stretch it. Lie on your back, cross one ankle over the opposite knee, and gently pull the uncrossed leg toward your chest for 60 seconds per side. Stretching works better when the muscle isn't holding tension.

Reactivate. Do bridges to switch the glute back on after reciprocal inhibition has kept it turned down. Then do clamshells to train the other hip rotators to share the work the piriformis has been doing. Do 2 sets of 10 of each.

I designed the Hip Hook to reach both the psoas, and more importantly, the iliacus, a deep hip flexor most tools can't reach. The Orbit is softer and wider, a gentle way to release the psoas and piriformis. This full low back, hip & sciatica routine walks through the releases, stretches, and exercises that were mentioned above in more detail.

When should you see a doctor for sciatica?

Muscle release is a reasonable place to start when your symptoms match the muscle pattern above. See a medical professional if you notice any of these:

• Numbness or weakness that keeps getting worse, rather than coming and going with activity
• A foot that drags or slaps when you walk (foot drop)
• Symptoms in both legs
• Pain that started after a fall, accident, or other injury
• Fever, unexplained weight loss, or a history of cancer
• Constant pain that doesn't change with position or movement
• No improvement after several weeks

Get emergency care right away for numbness in the groin or inner thighs, or any new change in bladder or bowel control.

Frequently asked questions

Why is my sciatica worse after sitting?

Sitting puts extra pressure on the structures around the sciatic nerve. It increases the load on the discs in your low back, especially when you slouch. It presses your weight directly onto the glute, where the sciatic nerve runs beneath a small muscle called the piriformis. And it keeps your hip flexors shortened for hours, which can leave the pelvis tilted when you stand up. Getting up and changing positions often helps take some of that load off.

Can sciatica affect both legs?

Yes, though it's less common than sciatica on one side. When both legs are affected, the cause is usually in the spine, such as a disc pressing straight back into the spinal canal or a narrowing of the canal called spinal stenosis. Sciatica that comes from muscle tension in the hip or glute tends to stay on one side.

Why does my sciatica leg feel weak?

Often it's because the muscles on that side are holding tension, not because they've lost strength. Tight muscles don't activate well, so the leg can feel unstable or tire quickly. Weakness that keeps getting worse can mean the nerve itself is involved, though, and needs a medical exam.

Should I stretch or strengthen the painful leg first?

Start by releasing muscle tension, then stretch, then strengthen. Holding steady pressure on a tight muscle for about 90 seconds helps it relax. A muscle that isn't holding tension stretches more easily and activates better when you strengthen it. If stretching sends pain shooting down your leg, back off, since that can mean the nerve is irritated.

How long does sciatica take to go away?

Sciatica often improves within four to six weeks, though some cases last longer. When muscle tension is part of the cause, many people in my clinic notice the ache down the leg ease within a few sessions of releasing the tight muscles, with the low back settling more slowly. If your symptoms aren't improving after several weeks, see a medical professional.

References

1. Smoll NR. Variations of the piriformis and sciatic nerve with clinical consequence: a review. Clin Anat. 2010;23(1):8-17. https://doi.org/10.1002/ca.20893
2. Neumann DA. Kinesiology of the hip: a focus on muscular actions. J Orthop Sports Phys Ther. 2010;40(2):82-94. https://doi.org/10.2519/jospt.2010.3025
3. Aali S, Rezazadeh F, Ardigò LP, Badicu G. Altered lower extremity muscle activity patterns due to iliopsoas tightness during single-leg landing. Sci Rep. 2025;15:9477. https://doi.org/10.1038/s41598-025-93905-6
4. Skorupska E, Dybek T, Rychlik M, et al. Amplified vasodilatation within the referred pain zone of trigger points is characteristic of gluteal syndrome: a type of nociplastic pain mimicking sciatica. J Clin Med. 2021;10(21):5146. https://doi.org/10.3390/jcm10215146
5. Ingber RS. Iliopsoas trigger point dry needling and therapeutic stretching in the treatment of a series of six consecutive patients presenting with acute lumbar radiculitis and foot drop. J Bodyw Mov Ther. 2023;36:1-4. https://doi.org/10.1016/j.jbmt.2023.04.073
6. van Tulder M, Peul W, Koes B. Sciatica: what the rheumatologist needs to know. Nat Rev Rheumatol. 2010;6:139-145. https://doi.org/10.1038/nrrheum.2010.3