Lower Back Pain on the Side: 7 Possible Causes

Written by Nikita Mistry
Physiotherapist, Western Sydney University
Medically reviewed by Dr Gina Arena
Research Fellow, University of Western Australia
Reviewed on June 21, 2022

Man holding his lower back on the left side while sitting at a computer

Left lower back pain is experienced on the left side of the body. The symptoms can vary, from a severe sharp pain to a dull aching pain. Low back pain is common, and many people experience it at some point in their lifetime.[1]

Most left lower back pain is caused by minor soft tissue injuries or mechanical issues.[2] However, pain can also be caused by a medical condition, such as organ problems or an underlying disorder.

Treatment for left lower back pain depends on the cause and the severity of the problem. Some people may respond well to movement, where it may worsen the pain for others. A health practitioner can distinguish between the different causes of the lower back pain and commence the appropriate treatment based on the diagnosis.

What are the symptoms of left lower back pain?

The symptoms of left lower back pain include:

What causes left lower back pain?

There are many different causes of low back pain. Most commonly left lower back pain is caused by a soft tissue injury, including a muscle strain or ligament sprain in the spine. Pain may also be caused by an injury to the joints or intervertebral discs. Less commonly, left side lower back pain can indicate a serious medical issue, such as an organ problem or underlying disorder.

1. Soft tissue injury

There are a lot of small but important muscles and ligaments in the lower back. When these structures are abnormally stretched or loaded more than they are capable of handling, it can cause pain in the left side of the low back.

This can occur from a sudden injury, from a simple everyday activity, or it may develop gradually over time with age. Mechanical issues such as poor posture when sitting for long periods of time or when lifting heavy items can contribute to the risk of low back pain.

2. Joint injuries

The spine is a complex structure made up of articulating bones which are supported by ligaments and muscles. Left lower back pain can be caused by injury to these structures.

  • Herniated disc - Between each vertebrae (spine bone) in the back are fibrocartilaginous discs called intervertebral discs. A herniated disc occurs when there is damage to the disc, which can cause pain and sometimes result in the disc impinging on a nerve.

  • Osteoarthritis - Osteoarthritis can develop in the spine from old age or injury. The cartilage and joint space degrades over time, which can cause stiffness and pain on the left side of the back. This is common in the facet joints (small articulating joints between the vertebrae).

  • Sacroiliac joint dysfunction - The sacroiliac joint is a large joint where the spinal column meets the pelvis. Dysfunction of this joint can cause pain to occur in the left lower back.

Other causes of left lower back pain

In some instances, lower back pain on the left side can be caused by a problem with one or more internal organs, such as:

    1. Kidney stones
    1. Infection, such as a kidney infection
    1. Pancreatitis
    1. Gut disorders, such as ulcerative colitis
    1. Endometriosis or fibroids.

Pain may also be caused by other medical conditions such as a spinal fracture, trauma, or underlying condition such as ankylosing spondylitis or scoliosis.

When to see a doctor

Lower back pain can indicate a serious medical condition. Seek urgent medical attention for symptoms including:

  • Severe, persistent, unrelenting pain

  • Loss of bladder or bowel control

  • Tingling, weakness, or numbness in the legs

  • Nausea or vomiting

  • Shortness of breath

  • Dizziness, confusion, or loss of consciousness

  • Fever or chills

  • Unexplained weight loss

  • Painful urination or blood in the urine

  • Any other unexplained symptoms.

How is left lower back pain diagnosed?

A health practitioner will take a detailed history and perform a physical examination to determine the cause of the left lower back pain and rule out any serious underlying medical conditions.

Given there are many different causes for pain in the left lower back, it is important to get the correct diagnosis before commencing a treatment plan.

How is left lower back pain treated?

Treatment depends on the location, cause, and severity of the symptoms. Common treatment strategies include:


Low back pain often resolves on its own. However, even mild symptoms of low back pain can impact daily activities. Common self-care strategies to manage symptoms and facilitate healing include:

  • Resting - A short period of relative rest can help settle any symptoms. It is important to avoid complete bed rest, as this can lead to a loss of muscle strength and may increase the symptoms in the longer term.

  • Activity modification - It may be helpful to avoid any aggravating factors, such as strenuous activity or long periods of sitting. Avoiding these activities for a short period of time can reduce the triggering cause and help resolve the pain.

  • Over-the-counter medication - Some over-the-counter medications can help reduce discomfort, including anti-inflammatories. It is important to check with a doctor if there are any concerns.

  • Cold/heat therapy - When used appropriately, cold packs or heat packs can help relieve pain and symptoms in the short-term.


A physiotherapist can help prescribe exercises and other treatments to help alleviate the pain and symptoms. This may include a walking program or an exercise regime that consists of strengthening and stretching movements. A slow, incremental increase in activity can help improve the function of the spine without overloading it.

The physiotherapist will also likely discuss strategies to improve posture, especially when lifting, exercising, or sitting. Better posture can reduce the risk of recurrent low back pain.

Medical treatment

If the pain is persistent, or does not respond to other treatments, a doctor may recommend:

  • Prescription medication, such as muscle relaxants or opioids

  • Corticosteroid injections.


In rare cases where the pain has not responded to any conversative treatment, a doctor may recommend a review with a surgeon to discuss surgical options. This is generally only considered as a last resort. The surgeon may recommend wearing a brace after surgery for a period of time.

In cases where the pain is caused by injury or trauma, a serious medical issue, or a severe underlying disorder, emergency surgery may be required.

Holistic treatment

Alternative holistic treatments for left lower back pain include:

  • Acupuncture

  • Meditation

  • Yoga

  • Soft tissue massage.

Things to consider about left lower back pain

Low back pain can be a very frustrating experience as it impacts everyday activities, including walking or going to work. As a result, it is one of the leading reasons for absence in the workplace.

Pain on the left side of the lower back has many different causes. Depending on the cause, the pain may simply resolve with time, or with simple treatment options. If the pain continues to persist, a visit to the doctor may be helpful to review the symptoms and discuss other treatment options.

Written by Nikita Mistry
Physiotherapist, Western Sydney University
Published on June 21, 2022
Medically reviewed by Dr Gina Arena
Research Fellow, University of Western Australia
Reviewed on June 21, 2022
Medical reviewers
Last medically reviewed on June 21, 2022
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