A twinge deep in the buttock that shoots down the back of the leg gets called sciatica by well-meaning friends, search results and, occasionally, a hurried clinician. Often the label is close enough. Sometimes it sends you down the wrong treatment path for months, because sciatica and piriformis syndrome overlap in where they hurt but not in why they hurt. One begins in the spine; the other begins in a muscle. Here is how to tell which one you are dealing with — and when to stop guessing and see a GP.
The difference in one sentence
Sciatica is a symptom, not a diagnosis: it describes pain travelling along the sciatic nerve because something is irritating a nerve root in the lower back. Piriformis syndrome is a specific diagnosis — still debated among clinicians — in which the piriformis muscle deep in the buttock compresses or irritates the sciatic nerve after it has left the spine.
That single distinction explains most of the differences you will notice in your own symptoms.
Where sciatica begins
The sciatic nerve is formed by nerve roots leaving the lower lumbar and upper sacral spine, which merge before running down the leg. When one of those roots is compressed or inflamed — most often by a bulging or herniated disc, sometimes by spinal stenosis or a narrowing of the space the nerve travels through — pain follows the nerve's territory.
Because the problem sits at the root, sciatica usually starts in the lower back and tracks through the buttock and down the back of the thigh. Pain reaching the calf, ankle or foot is a strong pointer towards a nerve root cause. So is pain that worsens when you cough, sneeze, strain, sit for long periods or bend forward.
Where piriformis syndrome begins
The piriformis is a small, deep muscle running from the sacrum to the top of the thigh bone. The sciatic nerve passes underneath it or, in some people, straight through it. When the muscle becomes tight, overworked or in spasm, it can press on the nerve at that point — outside the spine.
This pattern tends to follow overuse or pressure rather than a disc injury: long hours of sitting, driving, a sudden increase in running or hill walking, a fall onto the buttock, or a change in how you walk because of a hip or knee problem. Pain is usually felt deep in the buttock, sometimes with an area of tenderness you can press with a finger.
Comparing the symptoms
Clues that point towards sciatica
- Pain begins in the lower back and radiates down one leg, often past the knee
- Numbness, pins and needles or tingling in a band-like pattern in the leg or foot
- Weakness — tripping, a foot that slaps down, difficulty standing on tiptoes or heels
- Pain worse with coughing, sneezing, straining or sitting
- Raising a straight leg while lying on your back reproduces the pain
Clues that point towards piriformis syndrome
- Pain is centred on the buttock, with little or no back pain
- Discomfort may spread to the back of the thigh but rarely reaches the foot
- Sitting, driving or crossing your legs makes it worse; standing and walking often ease it
- Tenderness deep in the buttock, sometimes with a feeling of tightness or a knot
- Turning the hip outwards against resistance, or stretching the muscle, provokes the pain
- No true weakness or reflex changes on examination
Neither list is a diagnosis, and the two problems can occur together — a tight piriformis sitting on top of an irritated nerve root is not unusual. If your symptoms fit both columns, that is a good reason to have someone examine you rather than self-treat.
Why the distinction changes what you do
Most cases of sciatica settle over a few weeks to a few months with time, staying reasonably active and pain relief. Bed rest beyond a day or two tends to leave you stiffer and sorer. Physiotherapy aimed at restoring movement and strength is the usual next step, with imaging or specialist referral reserved for cases that do not improve or that show worrying features.
Piriformis syndrome responds to a different emphasis: calming the muscle, changing the sitting and training habits that tightened it, and strengthening the glutes so the workload is shared. Stretching a tight buttock muscle is helpful here — but if the real problem is a disc pressing on a nerve root, the same stretch can flare things up. That is why the label matters.
If a stretch or exercise consistently makes your leg pain worse, especially if it shoots below the knee, stop and get it assessed rather than pushing through.
Red flags: seek urgent help
Some symptoms need same-day assessment rather than a routine appointment. Contact NHS 111 or go to your nearest emergency department if you have:
- Numbness around the groin, genitals, buttocks or inner thighs — the “saddle” area
- New difficulty passing urine, a feeling that you cannot empty your bladder, or loss of bowel control
- Weakness or numbness in both legs, or weakness that is rapidly getting worse
- A foot that drags or drops, or you are unable to walk
- Severe pain after a significant fall or accident, or pain alongside fever, unexplained weight loss or a history of cancer
- Constant night pain that wakes you and is not eased by changing position
These are uncommon, but they can point to a compressed bundle of nerves or another serious problem that needs prompt treatment. Do not wait weeks to see whether they settle.
When to see a GP
Book an appointment if your pain has not improved after a few weeks of sensible self-care, if it is getting worse, if it is disturbing your sleep or stopping you walking and working, or if you have numbness, tingling or weakness in the leg. Ask sooner if you are unsure, if you need stronger pain relief than you can buy, or if you have a condition that affects your nerves, such as diabetes.
Your GP will ask when the pain started, where it travels, what makes it better or worse, and whether you have noticed any weakness or changes in sensation. They may check your reflexes, muscle strength and sensation, and test straight leg raising. From there, the usual routes are physiotherapy, pain relief, or referral to a specialist if symptoms are severe or persistent. An MRI is generally used only when surgery or an injection is being considered, or when red flags are present.
Before you go, note down three things: where the pain starts and where it travels, what makes it worse, and anything that has changed in your walking, bladder or bowel habits. That short list gives a clinician far more to work with than “my leg hurts”.
This article is general information, not a substitute for personal medical advice. If you are worried about your symptoms, speak to your GP, a physiotherapist or NHS 111.
Photo: jarmoluk / Pixabay
