Lower Back Pain: Causes and When to See a Doctor

Lower back pain is most often caused by strain on the muscles, ligaments or joints, and it usually gets better within a few weeks if you keep moving. See a doctor if the pain runs down your leg, lasts more than six weeks, wakes you at night or comes with a fever. This guide is by Dr. Pedro Yelamo Vera, a GP licensed in Spain (Colegiado No. 484814280).

Why does my lower back hurt?

The most common cause is mechanical: a strain, poor posture for a long time, lifting something heavy too fast, or long hours sitting. Doctors call it non-specific lower back pain. It hurts, but it does not mean serious damage. MedlinePlus and the NHS agree that most cases get better on their own within a few weeks.

Lack of exercise, extra weight, stress, poor sleep and pregnancy also play a part. With age, discs and joints wear (arthritis). This often shows on an X-ray even when it causes no pain.

In Spain doctors call it lumbalgia or dolor lumbar.

Is it back pain or kidney pain?

Muscle pain changes when you move or change position. Kidney pain is usually higher and to one side. It does not change with movement, and it may come with fever, burning when you pass urine, or blood in the urine. We explain the difference in kidney pain vs back pain.

What are sciatica and a slipped disc?

Sciatica is pain along the sciatic nerve. It runs from the buttock down the back of the leg, often below the knee. It may come with tingling, numbness or weakness. The most common cause is a slipped (herniated) disc, when part of a disc between the bones of the spine presses on a nerve root.

The NHS says sciatica usually gets better in about four to six weeks, though it can last longer. Only a few people need an MRI scan or surgery, mainly if weakness gets worse or the pain does not settle. In Spain a slipped disc is a hernia de disco, and sciatica is ciática.

Could it be the psoas muscle?

The psoas is a deep muscle that joins the lower spine to the thigh. When it is overworked, for example in runners or cyclists, or after long hours sitting, it hurts low in the back or in the groin. It hurts more when you lift your leg or stand up. Gentle stretches and a slow return to activity usually help. If you also have a fever and feel unwell, see a doctor soon, because rarely it can be an infection.

When is back pain inflammatory?

Some lower back pain is not mechanical but inflammatory, as in axial spondyloarthritis (once called ankylosing spondylitis). Signs that point to it:

• It starts slowly, before age 45.
• It lasts more than three months.
• Your back is stiff for more than half an hour in the morning.
• It gets better with exercise, not with rest.
• It wakes you in the second half of the night.
• It may switch from one buttock to the other, or come with heel pain, a red eye or psoriasis.

If this sounds like you, see a doctor. You will need blood tests and often a joint specialist (rheumatologist).

What can I do at home for lower back pain?

• Keep moving and slowly go back to your normal activities. Bed rest slows recovery.
• Put heat on the sore area.
• For pain you can take paracetamol or an anti-inflammatory such as ibuprofen, as the leaflet says, if it is safe for you.
• Walk, swim or do gentle back exercises.
• If you sit at work, change position often.

The dose and how long to take any painkiller are set by the leaflet or your doctor. Ask your pharmacist if you take other medicines.

Do I need an X-ray or MRI scan?

Hardly ever at the start. For back pain with no warning signs, scans do not change the treatment. They can also show wear that does not explain the pain. They are used if there are warning signs, or if the pain lasts for weeks without getting better.

When to see a doctor

• The pain is not better after a few weeks, or it is getting worse.
• It runs down your leg, or you have tingling or weakness.
• It wakes you at night or does not ease with rest.
• You are over 50 and the pain is new.
• You have lost weight for no reason, have had cancer, have thin bones or take steroids.
• It started after a fall or a blow.

When to go to A&E or call 112

Go to A&E (urgencias) now, or call 112, if back pain comes with:

• Numbness around your genitals or bottom.
• Not being able to pass urine, or losing control of your bladder or bowels.
• Weakness in both legs or trouble walking.
• A high fever and feeling very unwell.
• A bad fall or a hard blow.

The first three can be signs of cauda equina syndrome, which needs urgent care.

Frequently asked questions about lower back pain

Getting a medical assessment

If you are in Spain and have back pain, you can book a video consultation with Dr. Pedro Yelamo Vera, a physician registered in Spain. You can also read about back pain treatment and naproxen. A prescription is never guaranteed: it is issued only where clinically appropriate after a genuine evaluation, as a private electronic prescription under Spanish law. This service is for urgent, non-emergency care. In an emergency, call 112.

This guide is general information. It does not replace the package leaflet or the advice of your doctor or pharmacist.