This is the most important one on the list. Any change in your bladder or bowels alongside back pain needs taking seriously straight away. That means not being able to pass urine when you need to, leaking and being unable to control it, or losing control of your bowels.

Closely linked is numbness or pins and needles around the saddle area — the area that would touch a saddle if you sat on a bike, so the inner thighs, the groin and the back passage. If that area is going numb, tingly or feels different, especially alongside any of those bladder or bowel changes, that’s an emergency.

Together, these can be a sign that the nerves at the very bottom of the spine are being compressed. If this is happening, you go to A&E now — not tomorrow, now.

The next red flag is weakness or numbness spreading into both legs. Pain down one leg is common, and usually not an emergency. But both legs getting weak, heavy, numb, or giving way is a different picture. If your legs are genuinely losing strength or going numb together, that needs urgent assessment — get seen straight away.

Another is back pain after significant trauma — a fall from height, a car accident, a heavy direct blow to the back. If your back pain has come on straight after something like that, don’t just move around and tough it out; get it properly checked to rule out a fracture. This matters even more if you’re older, or you’ve been told you’ve got thinner bones (osteoporosis), because the bone can break far more easily.

The next red flag is back pain alongside feeling unwell in yourself. A fever, hot and cold sweats (especially at night), or feeling generally ill with it. The same goes for pain that’s constant, there all the time, and doesn’t ease at all when you rest — or pain that’s much worse at night and wakes you from sleep. Together, these can be a sign of an infection or something else going on, and they need checking out properly.

The final one is back pain with unexplained weight loss, or new persistent back pain when you’ve got a history of cancer. If the weight is dropping off you and you don’t know why, or you’ve had cancer in the past and you’ve developed new, persistent back pain, that’s a combination that should always be checked. Not to frighten you — but because it’s important not to miss.

So let me pull the back pain red flags together. Bladder or bowel changes. Numbness around the saddle area. Weakness or numbness in both legs. Pain after a serious accident. Feeling unwell, feverish, or pain that’s constant and worse at night. And unexplained weight loss, or a history of cancer.

If you’ve got any of those, this is not a wait-and-see situation. The bladder, bowel and saddle numbness ones especially mean straight to A&E. This article is for general education and isn’t a substitute for medical advice — if you’re worried any of these apply to you, contact your GP, call NHS 111, or go to A&E, and in an emergency call 999.

But I want to end where I started. If you’ve read all this and you’ve got none of these, that’s genuinely reassuring. It means your back pain, as grim as it feels, is very likely the ordinary kind — the kind that settles, and the kind we can help. So know the red flags and act on them if you see them. But if they’re not there, don’t panic — you’re very likely going to be just fine.

Joe Sharp
BSc (Hons) Physiotherapy