When Should You Get a Scan for Lower Back Pain?
Low back pain affects many Australians — whether you're into sport, working long hours, or managing everyday life. While it can feel worrying not knowing the cause of your pain, it is important to know when getting a scan is helpful - but also when it isn’t. Early or unnecessary imaging can cause extra cost, worry, radiation exposure, and treatments that might slow down, rather than speed up recovery.
The big picture
Most low back pain improves on its own within about 4–6 weeks.
Early scans don’t usually help with recovery.
Health professionals use a clinical assessment to screen for “red flags” that might require a scan - this is less than 5% of people.
If symptoms don’t improve or worsen after 6–12 weeks, and certain symptoms are present, a scan may become appropriate.
If imaging is done, the type matters, and more is not always better.
“🔍 A red flag is a warning sign that suggests your back pain might have a more serious cause. They don’t always mean something is wrong, but they increase caution, and might result in further investigations like a scan.”
What kind of scan should I have?
Here’s a simple breakdown of scan types and when they may be used:
X-ray
X-rays show bone structure, alignment, and major bony changes. They are best used for suspected fractures and spine alignment issues. They are low cost and quick, but give little detail about nerves/discs and other soft tissues, and may show “age-related” changes that are irrelevant.
MRI
MRIs show bones, discs, nerves, soft tissues, infection, and tumours. They are best used for when serious pathology or nerve compression is suspected. There is no radiation, but they cost more, and may reveal “incidental” changes that confuse rather than clarify.
CT Scan
CT scans show very detailed bone and spinal canal structure. They are best used when MRI isn’t possible (e.g. implants) or when detailed bone work is needed. They have a higher radiation, show less clarity for soft tissues like discs, and should not be the first choice for most cases of common back pain.
When should I have a scan?
1. Acute phase (first 0–4 weeks)
If you have no red flags or serious neurological problems, no routine imaging is recommended.
Focus on getting moving, gentle activity, staying out of bed rest, and simple pain relief.
2. Sub-acute phase (4–12 weeks)
If your back pain hasn’t settled, or you develop leg pain, tingling, or weakness, then imaging may be considered. You should be regularly reviewed by your healthcare provider.
If things are improving or stable, continue conservative care.
3. Chronic phase (3 months or more)
If symptoms persist or worsen despite good initial care, especially with nerve signs or specialist discussion, imaging becomes more justifiable — but only when it’s likely to change what happens next (for example, surgery or specialist referral).
“🔍 Tip to ask your clinician: “Will this scan change what we will do next?”If the answer is no, it’s usually better to wait and continue conservative care.”
Key Takeaways
✅ For most people with non-specific low back pain (i.e., no red flags, no nerve deficit), routine imaging early on does not improve outcomes, and may actually lead to worse results (RACGP guide; ACSQHC Clinical Care Standard).
✅ Imaging should be reserved for when serious pathology is suspected or when results are likely to change management. (Safety and Quality Commission)
✅ Most low back pain will improve with time and active care, without scans.
✅ Always ask: “Will this scan change what we will do next?”
✅ If you’re unsure, chat with your GP, physio or sport/musculoskeletal specialist — they’ll help you make decisions aligned with your goals and situation.