Low Back Pain: How to Spot Red Flags, When to Get Imaging, and What Exercises Actually Work

Most people will experience low back pain at some point in their life. It’s not rare-it’s normal. But when that pain sticks around, gets worse, or comes with strange symptoms, it’s easy to panic. Is it just a pulled muscle? Or could something serious be going on? The truth is, low back pain is almost always harmless. But knowing when it’s not-that’s what saves people from permanent damage and unnecessary scans.

Red Flags: What Actually Matters

Let’s cut through the noise. The real red flags-those that need immediate attention-are tied to four dangerous conditions: cancer, broken bones, infection, and cauda equina syndrome.

For cancer, the clearest warning signs are a history of cancer (especially breast, lung, or prostate) and unexplained weight loss-like dropping 10 pounds in a few months without trying. If you’ve had cancer before and now your back hurts, don’t wait. Same goes for someone on long-term steroids or with a weakened immune system. These aren’t just "maybe" signs-they’re strong indicators.

Fractures? Think trauma. A fall from height, a car crash, or even a simple stumble if you’re over 65 and have osteoporosis. If you’re on bone-thinning meds like prednisone and your back suddenly hurts after a minor bump, get checked. The sensitivity isn’t perfect, but the specificity is high. That means when it’s there, it’s usually real.

Now, the big one: cauda equina syndrome. This is rare-but devastating if missed. It happens when nerves at the bottom of your spine get crushed. The signs are unmistakable: you can’t control your bladder or bowels, you feel numbness in your saddle area (that’s the part that touches a bike seat), or you can’t feel your anal sphincter when the doctor checks. If you have urinary retention with more than 200cc left in your bladder after peeing, plus saddle numbness, your chance of having this is over 90%. This isn’t "wait and see" territory. You need an MRI within hours. Surgery within 48 hours gives you the best shot at avoiding permanent nerve damage.

And what about night pain? Or fever? These get thrown around a lot. Night pain can be a red flag, but it’s also common in people with just a stiff back. Fever? Sure, it could mean infection. But most people with low back pain and a low-grade fever have a virus-not spinal osteomyelitis. Don’t panic over these alone. They need to show up with other signs.

Imaging: When It Helps, When It Hurts

Why? Because scans show things that aren’t the problem. Bulging discs? Herniations? Degeneration? These are normal in people with zero pain. In fact, up to 40% of healthy 30-year-olds have disc bulges on MRI. Finding one doesn’t mean it’s causing your pain. But once you see it, your brain starts linking pain to that image-and suddenly, you’re scared to move, you avoid activity, and your recovery slows down.

Guidelines from the American College of Radiology, the Canadian Family Physicians Association, and the American Academy of Family Physicians all agree: if you have low back pain for less than 4 weeks and no red flags, don’t get imaging. Not an X-ray. Not an MRI. Nothing.

When is imaging appropriate? Only if red flags are present. For suspected cancer or nerve compression, MRI without contrast is the gold standard. For infection, a bone scan with SPECT/CT or a contrast-enhanced CT is better. X-rays? They’re almost useless unless you’ve had trauma or are over 70 with suspected fracture. Even then, they don’t show soft tissue damage. A negative X-ray doesn’t rule out a serious problem.

And here’s the kicker: a 2022 survey found that nearly half of primary care doctors still order X-rays for acute back pain without red flags. Why? Time pressure. Fear of missing something. Patient demand. But the cost isn’t just financial-it’s psychological. People who get early scans are more likely to develop chronic pain, take more opioids, and have more surgeries down the line.

Exercise Therapy: The Only Treatment That Works Long-Term

Exercise therapy isn’t just "good for you." It’s the most effective treatment for low back pain that we have. A Cochrane Review of 97 studies with nearly 20,000 people found that those who exercised had significantly less pain and better function than those who did nothing. The improvements lasted for months-even years.

Not all exercises are equal. Motor control exercises-like learning to engage your deep core muscles without gripping your glutes or holding your breath-have the strongest evidence. Graded activity, where you slowly increase your activity level even if you’re in pain, works well too. And combined programs-mixing strength, aerobic work, and flexibility-are the most practical for most people.

Here’s what a real exercise plan looks like:

1. Start with 2-3 supervised sessions per week for 4-6 weeks. A physiotherapist will teach you how to move safely.
2. Focus on control, not intensity. Don’t try to lift heavy right away. Learn to stabilize your spine first.
3. Progress gradually. After 4-6 weeks, increase strength work to 70-85% of your one-rep max. Add walking or cycling for 20-30 minutes, 3-5 days a week.
4. Transition to a home program. You don’t need a gym. Bodyweight squats, bridges, bird-dogs, and planks work just fine.

Adherence is everything. If you stop after two weeks, you get no benefit. Studies show that people who stick with exercise for 8-12 weeks cut their risk of future episodes by nearly 50%.

And here’s something most people don’t realize: you don’t need to be pain-free to start moving. In fact, moving while you’re sore is often the key to breaking the cycle. Pain doesn’t equal damage. It’s your nervous system being overly protective. Exercise retrains it.

What Doesn’t Work (And Why You Should Avoid It)

Braces? They make your muscles weaker. You become dependent on them. The evidence? Weak at best.

Chiropractic adjustments? They might feel good for a day or two. But they don’t reduce pain more than exercise or education. And if you have red flags, adjustments can be dangerous.

Spinal injections? Cortisone shots might temporarily reduce inflammation, but they don’t fix the root cause. And repeated shots can damage tissue over time.

And please, don’t rely on age as a red flag. Being over 50 or 55 doesn’t mean you have cancer or a fracture. That myth is still floating around clinics. A 2023 update to the UK’s NICE guidelines removed age over 55 as a red flag-because the data shows it doesn’t predict serious disease.

What You Can Do Today

• Stay active. Don’t rest. Walk. Move. Even if it’s slow.
• Look for red flags: unexplained weight loss, history of cancer, loss of bladder/bowel control, saddle numbness, or trauma. If any of these are present, go to urgent care or the ER.
• Don’t demand imaging. Ask your doctor: "Is there a red flag?" If not, ask: "Can I start moving?"
• Find a physiotherapist who specializes in back pain. Not one who pushes needles or machines. One who teaches you how to move better.
• Commit to 8-12 weeks of exercise. Even 15 minutes a day. Consistency beats intensity.

Low back pain is frustrating. It’s expensive. It’s misunderstood. But it doesn’t have to be a life sentence. Most people recover fully-not because of a scan, not because of a shot, but because they got moving, learned how to protect their back, and stopped fearing their own body.