Red flags

Red flags are warning signs that back or neck pain might have a serious cause. When clinicians assess low back pain, NICE asks them to think about other diagnoses and rule out specific causes such as cancer, infection, injury or inflammatory disease (NICE). Red flags are the questions and findings that point towards those causes.

They matter because serious causes are rare and easy to miss. In 1,172 people seeing a primary care clinician in Sydney for new low back pain, 11 (0.9%) turned out to have a serious condition, most often a vertebral fracture, and clinicians identified only 5 of the 11 at the first consultation (Henschke et al., 2009). For almost everyone else the pain is not dangerous, even though its exact cause is often not obvious (NHS): see non-specific low back pain.

What are the red flags for back pain?

The NHS groups them by how quickly you need help (NHS).

Call 999 or go to A&E if back pain comes with

• pain, tingling, weakness or numbness in both legs
• loss of feeling around your genitals or anus
• changes in your bladder or bowels, such as difficulty peeing, or peeing or pooing yourself
• changes in how your penis or vagina feels during sex, or problems getting an erection or reaching orgasm
• chest pain
• pain that started after a serious accident, such as a car accident

Several of these are warning signs of cauda equina syndrome, a rare but serious spinal condition that can cause permanent damage or disability and needs to be seen by an emergency specialist spinal team (NHS Fife). Back pain with leg pain, numbness or weakness is common, and on its own it does not necessarily need emergency care (NHS Fife); see sciatica.

Ask for an urgent GP appointment or call 111 if

• you feel hot, cold, shivery or generally unwell
• the pain is severe and started suddenly, or is getting worse quickly

See a GP if

• the pain has not improved after a few weeks or stops you doing everyday things
• you have lost weight without trying
• there is a lump or swelling in your back, or its shape has changed
• the pain does not ease with rest or is worse at night
• it is worse when you sneeze, cough or poo
• it comes from the top of your back, between the shoulders

Red flags for neck pain

Ask for an urgent GP appointment or contact NHS 111 if neck pain comes with heaviness or weakness in your arms or legs, pins and needles in an arm, pain between the shoulder blades, or severe pain that starts suddenly. Call 999 for new problems walking, loss of bladder or bowel control, a sudden lack of co-ordination (such as trouble buttoning a shirt), or a face drooping on one side, arm weakness or slurred speech (NHS). A stiff neck with a high temperature, a very painful headache, confusion or eyes that cannot bear bright light also needs 999, as it can be meningitis (NHS). Neck pain without these signs is covered in neck pain from desk work.

How reliable are red flags?

Less reliable than the lists suggest, which is why they guide an assessment rather than replace it:

• In the Sydney study, 80.4% of people had at least one red flag, yet fewer than 1% had a serious cause. Only three of the recommended red flags for fracture were informative: long-term steroid use, age over 70 and significant trauma (Henschke et al., 2009).
• A BMJ review of 14 studies and 53 red flags found that many in guidelines barely changed the chance of a fracture or cancer. The most useful for fracture were older age, long-term steroids, severe trauma and a bruise or graze; several together raised the chance sharply. For cancer, the strongest was a past history of cancer (Downie et al., 2013).
• An international framework led by the federation of orthopaedic manipulative physiotherapists noted that most red flags lack high-quality evidence for their accuracy, and set out a reasoning process for clinicians instead of a checklist (Finucane et al., 2020).

One item from the GP list does not mean something serious is happening, but the pain deserves a proper assessment. The 999 signs are different and should never wait.

Red flags are about serious disease and are not the same as yellow flags. Bavelu is exercise guidance, not a diagnosis, so if any red flag applies, see a doctor first.