Back pain is one of the most common reasons people seek medical advice in the UK.
In fact, most of us will experience it at some point in our lives.
When back pain strikes, it’s natural to want answers. Many people wonder whether they should get an MRI scan to find out exactly what’s causing the problem.
The answer, however, isn’t always straightforward.
As a GP, one of the most important things I tell patients is that most back pain does not require a scan.
That might sound surprising, but understanding why can help you make better decisions about your care.
The truth about most back pain
The vast majority of back pain is what doctors call “non-specific back pain.”
That doesn’t mean the pain isn’t real.
It simply means there isn’t a single serious underlying condition causing it.
Instead, symptoms are often related to muscles, ligaments, joints, discs, posture, activity levels, or a combination of factors.
The good news is that most episodes improve with time, movement, and appropriate rehabilitation.
For many people, staying active, performing targeted exercises, and gradually returning to normal activities is more helpful than extensive investigations.
Why an MRI isn’t always the answer
Many people assume that a scan will immediately reveal the cause of their pain.
The reality is more complicated.
As we get older, it’s common to develop changes in the spine that can be seen on MRI scans, even when we have no pain at all.
For example, an MRI may show:
- Disc bulges
- Wear and tear in the joints of the spine
- Degenerative disc changes
- Minor narrowing around nerves
While these findings sound worrying, they are often a normal part of ageing.
In many cases, they are not actually responsible for a person’s symptoms.
This is one reason doctors are careful about ordering MRI scans too early. Sometimes the scan identifies abnormalities that look significant but are unrelated to the pain itself.
When an MRI can be genuinely useful
Although most back pain doesn’t need imaging, there are situations where an MRI can provide important information.
Pain that isn’t improving
Most back pain gradually settles over a period of weeks.
If symptoms remain severe or unchanged despite appropriate treatment, further investigation may be appropriate.
Pain travelling down the leg
Pain that shoots down the leg, often called sciatica, can occur when a nerve becomes irritated or compressed.
An MRI can help identify whether a slipped disc or another spinal problem may be affecting the nerve.
Numbness, tingling, or weakness
Symptoms affecting the legs or feet can sometimes indicate nerve involvement.
In these situations, imaging may help guide treatment decisions.
Persistent pain affecting daily life
If back pain continues to interfere with work, exercise, sleep, or everyday activities despite rehabilitation, a scan may provide useful information.
When specialist treatment is being considered
If treatments such as injections, specialist pain management, or surgery are being discussed, MRI imaging is often needed to help plan the next steps.
When back pain may need urgent assessment
While serious causes of back pain are uncommon, there are certain symptoms that should never be ignored.
Seek urgent medical advice if back pain is associated with:
- Difficulty controlling your bladder or bowels
- Numbness around the buttocks or genitals
- Significant weakness in the legs
- Unexplained weight loss
- Fever or feeling unwell
- A history of cancer
- Severe pain following a significant injury
These symptoms don’t necessarily mean something serious is wrong, but they require prompt assessment.
What an MRI can show
MRI scans provide detailed images of the spine and surrounding tissues.
They can help identify:
- Slipped or prolapsed discs
- Pressure on spinal nerves
- Spinal narrowing that may affect nerves
- Stress injuries affecting the spine
- Signs of inflammation
- Certain infections
- Rarely, tumours or other serious conditions
Importantly, MRI can also help rule out these conditions, which can be reassuring for many people.
The question patients often ask
One of the most common questions I hear is:
“If I have back pain, wouldn’t it be better to just get scanned?”
Sometimes yes.
Often no.
A scan is most useful when the results are likely to change what happens next.
If the treatment would remain exactly the same regardless of the findings, an MRI may offer little benefit.
If the results could influence diagnosis, treatment, rehabilitation, or referral decisions, imaging becomes much more valuable.
The bottom line
Back pain is common, frustrating, and sometimes difficult to understand.
The good news is that most episodes improve without the need for scans, injections, or surgery.
However, there are situations where MRI imaging can provide important answers, particularly when symptoms persist, nerve involvement is suspected, or treatment decisions depend on having a clearer diagnosis.
The key is not to scan everyone with back pain.
It’s to identify the people for whom imaging is genuinely likely to make a difference.
Written by: Dr. Sachin Shah, GP, Dr.Online UK
Last reviewed: June 26