Pain in the lower left back could indicate a problem with the muscles, joints, mid-back, or organs in the pelvic area. Common sources of pain include muscle injuries, kidney problems, and arthritis.

Back pain is a common occurrence and can have many possible causes. The exact location of the pain is a key indicator of its cause. Left-sided organ pain may originate from the kidneys, pancreas, colon, or uterus.

Lower left back pain, or left flank pain, refers to pain in the area above the hip or buttocks. People may feel a shooting pain under the skin or a dull ache inside the back, depending on the cause.

This article discusses some of the most common causes of pain in the lower left back area.

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In most cases, lower back pain comes from a tissue injury. This could involve the muscles, bones, and ligaments in the back, spine, and surrounding areas. Injuries in one area can radiate out to other areas of the back.

Tissue injury pain is usually central, but it can occur to the left or right of the spine.

According to the American Association of Neurological Surgeons, lower back strains are the most common cause of lower back pain.

A muscle strain in the lower left back occurs when the muscle fibers overstretch, leading to inflammation.

In addition to pain in the lower back, symptoms may include:

  • a limited range of motion
  • muscle spasms
  • stiffness
  • pain that may worsen when getting out of bed

Heavy lifting, twisting, or a fall can cause muscle strain. Poor posture or sitting in an awkward position for too long can also lead to pain in one side of the lower back.

A slipped disk, also called a herniated disk, can cause pain to radiate from the central spine to one side of the back.

Small disks cushion the bones in the spine. Each disk has a firm outside, called the annulus fibrosis, and soft material inside, called the nucleus pulposus. A slipped disk involves fragments of the nucleus pushing through a weakness or tear in the outside of the disk, which then presses on the nerves.

A slipped disk can result from a sudden injury or develop over time due to wear and tear.

Symptoms may include:

  • tingling down one leg
  • pain on one side of the body
  • worsening back pain when walking

A kidney infection can cause a dull, aching pain on one side of the lower back. Other symptoms of a kidney infection include:

Adults over 65 may not experience these symptoms, but they may experience problems such as:

Learn to tell the difference between kidney pain and back pain here.

Kidney stones are deposits of minerals and salts that have crystallized and formed in a kidney. A stone may cause one-sided lower back pain as it passes through the urinary tract.

Symptoms may include:

  • painful urination
  • nausea
  • fever
  • blood in the urine

Kidney stones do not always have a clear cause.

Pancreatitis is inflammation of the pancreas, which sits in the upper abdomen, behind the stomach. The pancreas makes insulin and aids digestion.

Pancreatitis may be acute and come on suddenly or develop gradually and become chronic.

Alcohol use disorder or abdominal surgery can cause this condition, and the inflammation can also be a side effect of certain medications.

Symptoms may include:

  • upper abdominal pain
  • abdominal pain that radiates to the back
  • fever
  • nausea

Back pain on the left side in females can result from endometriosis. This condition involves uterine tissues forming and collecting outside of the uterus. Doctors are still unsure of the exact cause.

The pain from endometriosis can be sporadic and occur in one side of the lower back. Additional symptoms include:

  • fatigue
  • abdominal pain
  • severe menstruation pain

According to the Arthritis Foundation, several forms of the disease can cause pain in the lower back. In some cases, the pain occurs on only one side.

Arthritis that affects the back may result from inflammation or deterioration of cartilage. Symptoms vary, depending on the type of arthritis, but may include:

  • back stiffness
  • swelling in the back
  • decreased range of motion

Treatment for lower left back pain varies widely, depending on the cause, so getting an accurate diagnosis is critical.

A doctor often performs a physical exam, takes a medical history, and reviews the person’s symptoms before reaching a diagnosis. Tests, including CT scans, X-rays, MRIs, and ultrasounds, are also helpful.

When back pain originates from an issue affecting an organ, treating the underlying cause can reduce the discomfort. Examples of these treatments include:

  • Pancreatitis: A surgeon may remove a bile duct obstruction or drain fluid from the pancreas.
  • Kidney stones: A doctor may recommend medication or shockwave therapy to break up the stones.
  • Endometriosis: A doctor may recommend medication or surgery to remove excess tissue.

When lower left back pain results from a musculoskeletal condition, try:

  • Rest: Although doctors rarely recommend complete bed rest, it helps to limit activities that cause lower back pain.
  • Ice: Applying an ice pack wrapped in a cloth to the area several times a day can decrease inflammation and discomfort.
  • Heat: Applying heat may also reduce lower back pain, especially if it results from muscle strain.
  • Medication: Over-the-counter anti-inflammatory medications can reduce inflammation and discomfort, as can prescription pain medications and muscle relaxants.
  • Light exercise: Depending on the cause of the pain, light exercise may reduce discomfort and stiffness in the long term and help improve the range of motion.

Anyone with back pain should consult a doctor before starting an exercise program.

Alternative treatments that may help ease lower left back pain include:

Lower left back pain varies in severity. It may be mild and ease within a few days, in which case home remedies can help. But in certain instances, it is important to see a doctor.

Consider seeing a doctor if the pain does not get better in 1–2 weeks or if it becomes worse. If additional symptoms are present, such as numbness, fatigue, and muscle weakness, see a healthcare provider to rule out serious conditions.

Less frequently, lower left back pain constitutes an emergency that requires prompt medical treatment. If the pain is severe or accompanied by any of the following symptoms, seek immediate medical care:

  • fever
  • trouble moving the legs
  • loss of bowel control
  • loss of feeling in the legs

Lower left back pain can stem from various issues, including internal organ problems and musculoskeletal injuries or conditions. Accompanying symptoms and the location of the pain can help a doctor diagnose the cause.

A person can take steps at home to ease the pain, and symptoms often reduce in a few days. When the pain is severe or other symptoms cause concern, it is best to see a doctor. Treatment varies, depending on the cause.