--- title: "Pillow between your knees hurts your hips? Why, and the fix" url: https://thesidesleeper.com/knee-pillows/hurts-hips/ published: 2026-10-05 updated: 2026-10-09 --- [Knee pillow guides](https://thesidesleeper.com/knee-pillows/) # Pillow between your knees hurts your hips? Why, and the fix **Nell, the Side Sleeper** Updated October 9, 2026 · Data collected October 5, 2026 · [How we research](https://thesidesleeper.com/how-we-research/) **Usually the pillow is the wrong height for you.** If it's too thick, it props your top leg up. If it's too thin, or squashed flat by 3 a.m., your top knee drops anyway. A third cause is a short pillow that holds your knees while your foot sags. Before any of that, check which hip hurts. If it's the one you're lying _on_, the knee pillow probably isn't the problem. ![Someone lying face down across a white bed, arms over their head.](https://thesidesleeper.com/_astro/face-down-on-bed.BB-TgOIl_1IOh1h.jpg) Photo: [rawpixel](https://www.rawpixel.com/image/5922647/girl-lying-bed-free-public-domain-cc0-image) ## First: which hip hurts? - **The hip on top** (the one facing the ceiling). This is the hip a knee pillow affects, because it sets the angle of your top leg. Read on. - **The hip underneath** (the one pressed into the mattress). That's pressure from the mattress, and nothing between your knees changes it. NHS advice for outer-hip pain is to avoid lying on the painful side: sleep on the other side with a pillow between your legs, or on your back with a pillow under your knees. - **Both, or you can't tell.** Work through the height checks below anyway. They're free, and they rule things out. ## What the right height looks like A knee pillow is there to keep your top leg in line with your hip. The NHS describes it as keeping your legs "in line with your hip joints". Seen from the foot of the bed, your top thigh should run level with the mattress. It goes wrong in two directions: **✗ Too thin** Top knee drops, thigh slopes down **✓ About right** Top thigh level with the hip **✗ Too thick** Top knee pushed up above the hip Seen from the foot of the bed, lying on your side with knees bent. The dashed line is the height of your top hip. A pillow is the right thickness when the top thigh follows it. Schematic, not to scale. ## Cause 1: the pillow is too thick A pillow taller than your knee gap pushes your top knee _above_ your hip and holds the leg open all night. That tips your pelvis the opposite way to the one the pillow was meant to stop. Depending on the person, it can show up as an ache in the outer hip, the groin or inner thigh, or the lower back. It's more likely if you're slim-hipped and bought a tall pillow. Compact knee pillows with a clearly stated thickness run from 5 to 7.2 inches, and the tallest fixed ones are the heart shapes at 7.2″. That's a big gap for narrow hips. **The fix:** find your own gap with the [towel test](https://thesidesleeper.com/knee-pillows/thickness/), then compare it with your pillow's listed height. If yours is taller, you can go thinner, or pick something you can adjust. The Coop Home Goods Adjustable Knee Pillow uses removable inserts to run from 5″ to 8″. A softer filling helps too: [shredded foam and fibre](https://thesidesleeper.com/knee-pillows/fillings/) squash further than solid foam. ## Cause 2: too thin, or thin by morning If the pillow is too thin, the top knee still drops toward the mattress and your top leg ends up angled across your body. That's close to the position of sitting with your legs crossed, which the NHS lists among the things that aggravate pain on the outside of the hip. A pillow can also start the night at the right height and lose it. [Memory foam](https://thesidesleeper.com/knee-pillows/fillings/) softens with body heat, and shredded fill shifts and packs down, so the 6.5″ listed for the HOMBYS Shredded Memory Foam Knee Pillow 6.5" is the height before your leg is on it. If the ache only turns up in the early hours, suspect this. **The fix:** slip a folded towel on top of your pillow for a night or two. If that helps, you need a thicker pillow. The [comparison table](https://thesidesleeper.com/knee-pillows/compared/) lists every best seller's thickness, where the listing actually gives one. ## Cause 3: your knees are held, but your foot isn't A compact pillow only fills the space between your knees. With nothing between your lower legs, your top foot can sag toward the mattress, and that turns your top thigh inward at the hip. Not everyone notices it, but if you wake with your top foot dangling below your knee, this may be your cause. **The fix:** you can tuck a second, small pillow between your ankles. Or look at the full-leg pillows, which run 26 to 29 inches from knee or hip down to the ankle. There are 3 in the [comparison table](https://thesidesleeper.com/knee-pillows/compared/). They tend to be thinner than compact pillows, because the whole leg rests on them. ## Cause 4: it's new Any change in sleeping position feels odd for a while. One listing, for the TULARIS Heart Knee Pillow with Adjustable Strap, says to allow 3–7 nights to get used to the pillow. That's the seller talking, but a few nights' patience is fair. If it's the same ache in the same place after a week, though, that tells you something, and the causes above are where to look. ## The fix, in order 1. **Work out which hip hurts.** If it's the one you lie on, the mattress or your position needs attention, not the knee pillow. 2. **Do the [towel test](https://thesidesleeper.com/knee-pillows/thickness/)** to find the knee gap you need. 3. **Compare it with your pillow.** Use the listed height, and remember that contoured shapes hold your knees a little closer than their listed height. 4. **Too tall?** Go thinner, or pick an adjustable or shredded-fill pillow. **Too short, or flat by morning?** Test with a towel on top, then size up. 5. **Foot sagging?** Add support between your ankles, or try a full-leg pillow. ## When it isn't the pillow Hip pain that comes on lying on your side is common, especially for women from their 40s onward. One of the most frequent causes, greater trochanteric pain syndrome, has an [NHS page in plain English](https://www.nhsinform.scot/illnesses-and-conditions/muscle-bone-and-joints/leg-and-foot-problems-and-conditions/greater-trochanteric-pain-syndrome/). It suggests talking to a healthcare professional if things haven't improved within 6 weeks or are getting worse. If the pain wakes you most nights whatever you put between your knees, don't wait the six weeks. ## Quick answers ### Can a pillow between your knees cause hip pain? Yes, when it’s the wrong height. A pillow that’s too thick holds your top knee above your hip; one that’s too thin, or flat by morning, lets the knee drop across your body. Either can leave the top hip aching. If it’s the hip you lie on that hurts, the knee pillow probably isn’t the cause. ### Which hip should a knee pillow help? The top one, facing the ceiling. A knee pillow sets the angle of your top leg, so it affects that hip. An ache in the hip pressed into the mattress comes from pressure, and nothing between your knees changes it. ### Should I stop using a knee pillow if my hip hurts? Check the height before giving up. Find your knee gap with a towel test and compare it with the pillow. If yours is taller, go thinner or adjustable; if it’s flat by morning, try a folded towel on top. If the same ache is still there after a week, or the pain wakes you most nights whatever you use, see a doctor or physiotherapist. ## Sources - Sleeping positions and outer-hip pain: [Greater trochanteric pain syndrome, NHS inform](https://www.nhsinform.scot/illnesses-and-conditions/muscle-bone-and-joints/leg-and-foot-problems-and-conditions/greater-trochanteric-pain-syndrome/). - Background: [Greater Trochanteric Pain Syndrome, StatPearls (NCBI)](https://www.ncbi.nlm.nih.gov/books/NBK557433/). - Pillow heights and listing claims: Amazon US listings and manufacturer pages, collected October 5, 2026. See [knee pillows compared](https://thesidesleeper.com/knee-pillows/compared/). ## Keep reading [### Why sleep with a pillow between your knees?](https://thesidesleeper.com/knee-pillows/benefits/)[### How thick should a knee pillow be?](https://thesidesleeper.com/knee-pillows/thickness/)[### How to use a knee pillow](https://thesidesleeper.com/knee-pillows/how-to-use/)[### Knee pillow vs body pillow vs a regular pillow](https://thesidesleeper.com/knee-pillows/vs-body-pillow/)[### Knee pillow shapes, explained](https://thesidesleeper.com/knee-pillows/shapes/)[### Knee pillow fillings, explained](https://thesidesleeper.com/knee-pillows/fillings/)[### Knee pillow listings, by the numbers](https://thesidesleeper.com/knee-pillows/findings/)[### Knee pillows compared](https://thesidesleeper.com/knee-pillows/compared/)