Acute low back pain (lumbago): causes, course and what you can do

Lumbago is used about acute pain in the lower back [1][2]. Low back pain is divided by duration. NHI regards pain lasting under four weeks as acute, while the Lægehåndbogen uses six weeks as the limit [2][3].

The most common form is called non-specific low back pain and accounts for 80 to 90 percent of cases [2][3]. Non-specific means that the examination does not point to a particular injury or disease as the explanation. It does not mean the pain is imagined, and it can be very unpleasant.

Back pain is common. NHI states that an estimated 60 to 80 percent of the population has troublesome back pain at some point in life [1][2]. You can read more on the page about back kinks and the page about low back pain.

The pain often comes suddenly. Muscle tension is common, and the pain can radiate to the buttock or be diffuse in the thigh. It is often better at rest [1][2]. Examination typically shows reduced mobility of the back and tension in the muscles along the spine [3].

The cause is often unclear. NHI mentions heavy lifting, twisting, one-sided work, poor fitness and inactivity, well-being at work and at home, and heredity as possible contributing factors. The associations are usually weak, and several factors often work together [1].

Pain radiating below the knee, with numbness or tingling, can indicate that a nerve root is involved. This applies to roughly 5 to 10 percent, and the condition is referred to as sciatica [1][2][3]. Serious underlying causes are rare, and NHI states that they account for less than one percent of cases of acute back pain [2].

The diagnosis is made from the history and a clinical examination [3]. The clinician asks, among other things, about the intensity and spread of the pain, what eases and worsens it, earlier back problems, strength and sensation in the legs, and whether there are problems passing urine or stool [2]. If a nerve root may be involved, walking, mobility, strength, sensation and reflexes are also examined [2][3].

The aim is to distinguish ordinary back pain from the few cases that need prompt assessment by a doctor, and the sources use the term red flags for such warning signs [3]. Examples are known cancer, fever, weight loss, increasing constant pain and reduced strength [2][3].

Imaging is not routine in acute back pain. Both NHI and the Lægehåndbogen advise against routine MRI and X-ray when there is no suspicion of serious disease [1][3]. MRI is considered if the pain is largely unchanged after four to six weeks [1][2]. Degenerative findings also correlate poorly with symptoms [3].

The most important advice is to keep moving. NHI recommends being as active as possible and resuming everyday activities and work quickly, and states that pain during activity is not dangerous [1]. The Lægehåndbogen describes continued normal activity as the most important treatment [3].

Bed rest is not recommended. The Lægehåndbogen says it does not improve recovery and should be limited to a maximum of two days, only when the person cannot stay up. NHI says that a short time at rest can be necessary with severe nerve root pain [1][3]. Over-the-counter pain relief can help [1][3].

Manual treatment can be considered. NHI mentions it if you have not improved after one to two weeks, and says it is provided by a chiropractor or physiotherapist specialised in manual therapy [1]. The Lægehåndbogen writes that manual joint mobilisation or manipulation can be considered for recent-onset pain, as an addition to usual care [3].

Exercises have no clear effect in the acute phase itself, but physical activity over time can prevent recurrences [3]. NHI says that an exercise programme with a physiotherapist can be relevant after four to six weeks [1]. Traction, ultrasound and TENS are not recommended, nor are corsets or back supports [3].

Most people are well or considerably better within a few weeks [1]. NHI writes that the vast majority recover within one to two weeks [2]. The Lægehåndbogen states that around 90 percent are regarded as recovered within six weeks, but that the figures rest on traditional estimates and that mild pain and reduced function can last longer [3].

Recurrences are common. The Lægehåndbogen states that about 75 percent have at least one recurrence within twelve months, and that chronic development after a first episode is rare [3]. NHI writes that many have episodic pain that is not dangerous [1]. Nerve root pain can last for several months [1]. If there is no improvement after six to eight weeks, further assessment may be relevant [2].

Contact a doctor or emergency service straight away if you have problems passing urine or become numb in the groin. NHI writes that this can be caused by a large disc herniation that in some cases must be operated on within 24 hours [1][2]. The same applies to reduced muscle strength in the legs [1].

Also seek help if the pain is severe and eased too little by offloading and pain relief, if you are unsure what is causing it, or if you develop fever, unintentional weight loss or feel generally unwell [1][2]. The same applies to pain that is constant or increasing, to known cancer, or after an injury [2]. Pain that does not improve quickly should also be assessed [1].

A chiropractor can examine your back, assess whether there are signs that call for further evaluation by a doctor, and plan with you how to get back to activity. You can read more about chiropractic care at Dr.Dropin. If you have pain radiating down the leg, you can read about disc herniation.

What is a witch's shot (hekseskudd)?

Hekseskudd is a common Norwegian term for sudden pain in the lower back, medically called acute lumbago. The cause is often unclear [1][2].

How long does lumbago last?

Most people are well or considerably better within a few weeks [1]. Recurrences are nevertheless common [3].

Should I rest in bed with lumbago?

The sources do not recommend bed rest. Stay active as far as the pain allows, and resume daily life and work as soon as you can [1][3].

Do I need an MRI for acute back pain?

Usually not. The guidelines advise against routine imaging when there is no suspicion of serious disease [1][3].

When is back pain an emergency?

Problems passing urine, numbness in the groin and reduced strength in the legs require prompt assessment by a doctor or emergency service [1][2].

The page about disc herniation describes pain from the back that radiates down the leg. The article on sciatica covers the same topic from another starting point. You can find more articles in the overview of articles.

This article was written by Dr.Dropin Fysikalske and is based on the sources listed below. It gives general information and does not replace an examination by a healthcare professional.

The websites were accessed and read on 22 October 2026.

1. Akutte ryggplager (korsryggsmerter) (Acute back problems, low back pain). NHI.no (Norsk Helseinformatikk), published by Nasjonalt ryggnett. Last updated 10 November 2021. Link

2. Vondt i korsryggen? Årsaker til smerter og legehjelp (Low back pain? Causes and when to seek help). NHI.no (Norsk Helseinformatikk). Last updated 5 October 2020. Link

3. Kold S. Lændesmerter - lave rygsmerter (Low back pain). Lægehåndbogen, sundhed.dk (Danish College of General Practitioners). Professional update 15 January 2024. Link