You bent to pick up a bag, twisted to grab something from the back seat or simply woke up and could not straighten. Now your back has seized, every movement is painful and you are wondering whether you have done something serious.

Acute low back pain is one of the most common reasons people come to see us, and one of the most likely to recover well. This article explains what is usually going on, what to do in the first days and weeks, what to avoid, and the few situations that need a doctor rather than a physio or chiro.

What is acute low back pain?

Acute means recent. Clinically, low back pain is called acute for the first six weeks, sub-acute from six to twelve weeks and persistent beyond that. Most episodes are over well before the first mark.

Around nine in ten cases are what is called non-specific low back pain. That means there is no single injured structure that can be identified as the cause, and no serious condition behind it. That sounds vague, but it is a reassuring diagnosis: it means the joints, discs, ligaments and muscles of the back have been strained or irritated, the same way an ankle is sprained, and they will settle.

The remaining minority is made up of nerve root problems such as sciatica, and a small number of specific causes such as fracture, infection or inflammatory disease. Picking those out is the main job of a first assessment.

Why does lower back pain hurt so much?

The intensity of acute back pain catches people out. A back that seized while you tied your shoelaces can hurt more than a broken bone, and that mismatch makes people fear the worst.

The lower back is densely supplied with nerves, and when the area is irritated the surrounding muscles clamp down to protect it. That protective spasm is often the biggest source of pain in the first few days. It also produces the classic picture of being stuck bent to one side or unable to stand upright. The muscle guarding feels like damage. In most cases it is a strong protective reaction to a fairly minor strain.

Pain intensity is a poor guide to how much tissue damage there is, and it is an even worse guide to how you will recover. Severe pain in the first week does not predict a bad outcome.

What usually causes lower back pain?

Sometimes there is an obvious event: a heavy or awkward lift, a fall, a tackle or a sudden twist. Just as often there is not. Bending to pick up a sock, sneezing, sitting up in bed or a long drive are all common triggers. When something trivial sets it off, it usually means the back was already primed by a combination of factors: a run of poor sleep, a stressful week, a spike in training or physical work, a long period of sitting, or general deconditioning.

Which structure is involved varies. It might be the small facet joints at the back of the spine, the disc, the ligaments or the muscles themselves. In practice we often cannot say with certainty, and it rarely matters for management in the first few weeks because the approach is the same.

How long does lower back pain take to recover?

Most people with acute low back pain improve substantially within two to four weeks and are largely recovered within six. Pooled studies show pain and disability dropping steeply in the first month, then continuing to improve more slowly.

Recurrences are common. Around a third of people have another episode within a year, which is why the back deserves some attention once the acute pain has settled, rather than being forgotten until next time.

A smaller group, roughly one in five, still has some pain at three months. The factors that predict that are less about the injury and more about how people respond to it: high levels of fear about movement, believing the back is damaged, avoiding activity, low mood, and job dissatisfaction or heavy work with no room to modify. Most of these can be changed, which is why good early advice matters.

What to do in the first 48 hours after hurting your back

• Keep moving. Bed rest is the single most reliable way to slow recovery. Lying down for short periods to ease pain is fine. Staying there for days is not. Get up, walk around the house, and change position every 20 to 30 minutes.
• Walk. Short, frequent walks are usually the best tolerated activity. Start with five to ten minutes and build.
• Use heat or ice for comfort. Neither speeds healing, but a heat pack often eases muscle spasm. Use whichever feels better.
• Find positions of ease. Lying on your back with knees bent and a pillow under them, or on your side with a pillow between the knees, is comfortable for most people. Sitting is often the hardest position early on, so keep sitting spells short.
• Consider simple pain relief. Check with your pharmacist or GP. Paracetamol has been shown to be no better than placebo for acute back pain, while anti-inflammatories give modest short term relief for some people. Medication is there to help you move, not to fix the back.
• Breathe. When pain is high, people brace and hold their breath, which increases muscle tension. Slow breathing out while you move helps.

What to do over the next few weeks

As the initial spasm eases, usually within a few days, the aim shifts to gradually restoring normal movement and getting back to your usual activities, including work and sport.

• Reintroduce activities progressively rather than waiting to be pain free. Do a little of each thing, notice how your back responds over the next day, and increase from there.
• Gentle movement in all directions. Bending forward, backward and side to side within a tolerable range helps the back stop guarding.
• Return to work early, with modifications if needed. People who return to work during recovery do better than those who wait until they are fully recovered.
• Start simple strength work once walking is comfortable. Bridges, sit to stand, step-ups and light carries are a reasonable starting point.
• Keep general activity up. Swimming, cycling and walking are all fine if they are comfortable.

What not to do

• Do not rest in bed for more than a day or two.
• Do not stop all activity until the pain is gone. Waiting for zero pain before moving usually means waiting a long time and getting stiffer.
• Do not brace or hold yourself rigid. A stiff, guarded back hurts more, not less.
• Do not wear a back brace for weeks. It has not been shown to help and it encourages reliance.
• Do not rush to get a scan.
• Do not treat every twinge as a re-injury. Flares in the first few weeks are normal.

Do you need a scan?

Almost never in the first six weeks unless there are warning signs. Australian and international guidelines are consistent on this. Early imaging does not improve outcomes and often makes them worse, because reports list disc bulges, degeneration and other findings that are common in people with no pain at all, and reading those words tends to make people move less and worry more.

An X-ray does not show discs, nerves or muscles, and an MRI in the first few weeks rarely changes what we do. Imaging is warranted after significant trauma, when there are nerve symptoms that are severe or progressive, when a serious cause is suspected, or when a good block of treatment has not produced improvement.

When to see a doctor rather than a physio for lower back pain

The vast majority of acute back pain is not dangerous. Seek prompt medical review if your back pain comes with any of the following:

• Numbness around the genitals, anus or inner thighs, new difficulty passing urine, or loss of bladder or bowel control. Go to an emergency department the same day.
• Weakness in one or both legs that is getting worse.
• A significant fall, car accident or heavy collision, particularly if you are over 65 or have osteoporosis.
• Fever, feeling unwell, or a recent infection.
• Unexplained weight loss or a history of cancer.
• Constant pain, including at night, that is not eased by any position.
• Pain that came on gradually before the age of 40 with morning stiffness lasting more than half an hour and improving with exercise, which can suggest an inflammatory condition.

We screen for all of these at the first appointment. If anything is not right, we will refer you the same day.

What if my back pain is causing sciatica?

If your pain travels down one leg below the knee, especially with pins and needles, numbness or weakness, a nerve root may be irritated, most often by a disc. The outlook is still good, with most people improving over a few months, but the management is a little different and it needs a proper neurological check. We have a separate article on sciatica that covers this in detail.

Pain that spreads into the buttock and back of the thigh without those nerve features is referred pain from the back itself, and it is managed as part of the back pain.

What treatment at VIBE looks like for lower back pain

Your first appointment starts with a detailed history and a screen for the warning signs above. We then examine how you move, test your nerves where needed, and work out which movements and positions ease your pain and which aggravate it. You will leave knowing what is going on in plain language, what the likely timeline is, and exactly what to do over the next week.

Hands-on treatment such as mobilisation, manipulation or soft tissue work is used early to reduce pain and muscle guarding and get you moving with more confidence. The evidence shows this helps in the short term, particularly when combined with activity. As the pain settles, the focus moves to restoring full movement, building strength and getting you back to work and training.

Most people with acute non-specific back pain need only a small number of sessions. If you are not tracking as expected, we will reassess rather than continue with the same plan.

Preventing the next episode of lower back pain

Once the acute pain is behind you, the best predictor of another episode is what you do with your back in between. The things with the best evidence:

• Regular exercise. Any type helps. General strength training, walking and specific back and hip strengthening all reduce recurrence.
• Keep bending and lifting. A back that is regularly exposed to bending and load tolerates it. One that is protected becomes sensitive.
• Manage the load spikes. Big jumps in training, work or gardening are common triggers.
• Sleep and stress. Both feed directly into how sensitive your back is.
• A short plan for next time. Knowing what to do in the first 48 hours turns a frightening episode into a manageable one.

Wrap-up

Acute low back pain is common, often frighteningly painful and usually not serious. The large majority of episodes settle within a few weeks, and the things that make the biggest difference are staying active, walking, finding positions that ease the pain and getting back to normal activities early rather than waiting to be pain free. Scans are rarely needed, bed rest and bracing slow recovery, and a small number of warning signs need medical attention.

If your back has gone and you want to know what is going on and what to do about it, book an assessment with one of our physiotherapists or chiropractors at VIBE Health & Performance in Homebush or Seven Hills. And if you have any of the urgent symptoms listed above, go straight to emergency.