Lower Left Back Pain: Causes, Red Flags & When to See a Doctor

📅 2026-05-11✎ The Vesey Clinical Team⏱ 6 min read

This guide provides clinician-verified information about lower left back pain — its most common causes, the symptoms that require urgent assessment, and when to seek private medical review at The Vesey, Sutton Coldfield, Birmingham.

What Causes Lower Left Back Pain?

Lower left back pain has a broad range of causes, spanning musculoskeletal, renal, gastrointestinal, and — in women — gynaecological origins. The vast majority of cases are musculoskeletal in nature and resolve with appropriate conservative management. However, distinguishing musculoskeletal pain from visceral causes (pain from internal organs) is clinically important and sometimes requires investigation.

Musculoskeletal Causes (Most Common)

The most frequent cause of lower left back pain is a problem with the muscles, ligaments, joints, or intervertebral discs of the lumbar spine.

• Muscle strain or ligament sprain — the most common cause overall, often related to overuse, sudden movement, or poor lifting technique. Pain is typically worse with movement and eases with rest.
• Lumbar disc herniation — when disc material presses on a nerve root (sciatica), pain can radiate from the lower left back down the left leg. Associated numbness or tingling suggests nerve involvement.
• Lumbar facet joint arthropathy — degeneration of the small joints of the lumbar spine, causing localised back pain that is often worse in the morning and with sustained positions.
• Sacroiliac (SI) joint dysfunction — the joint between the sacrum and pelvis can be a source of left-sided lower back and buttock pain, particularly in women during and after pregnancy.

What Organ Is on the Left Side of Your Back?

Several organs can cause pain perceived in the lower left back area:

• Left kidney — sits at the back of the abdominal cavity at the level of the lower ribs. Kidney stones, kidney infections (pyelonephritis), and cysts can all cause flank pain — felt in the back at roughly the kidney's level — that radiates downward toward the groin.
• Left ureter — as a kidney stone passes, pain follows the ureter's path from the flank down toward the groin and genitals.
• Descending and sigmoid colon — diverticulitis (inflammation of pouches in the colon wall) most commonly affects the sigmoid colon on the left and can cause lower left abdominal and back pain, often with fever.
• Left ovary and fallopian tube (women) — ovarian cysts, endometriosis, and pelvic inflammatory disease can all cause left-sided lower abdominal and back pain.
• Abdominal aorta — in older patients with vascular risk factors, an aortic aneurysm should be considered in any new lower back pain presentation.

Renal Causes of Left Back Pain

Kidney-related pain (renal colic) typically presents in the costovertebral angle — the area between the lower ribs and the spine — and radiates downward. It is often colicky (coming in waves), severe, and accompanied by urinary symptoms such as blood in the urine, frequency, or burning urination. A high temperature with back pain suggests a kidney infection (pyelonephritis) and requires urgent medical attention.

Distinguishing kidney pain from musculoskeletal back pain is important: kidney pain is typically not affected by movement or position, whereas musculoskeletal pain usually worsens with movement and is relieved by rest.

Left-Sided Back Pain in Women

Women have additional potential causes of lower left back pain that should be considered when no clear musculoskeletal cause is identified. Endometriosis — in which endometrial tissue grows outside the uterus — commonly affects the left pelvis and can cause cyclical lower back and pelvic pain. Ovarian cysts can cause sudden, sharp left-sided pain if they rupture or undergo torsion (twisting), which constitutes a gynaecological emergency. Pelvic inflammatory disease (PID) causes chronic bilateral or unilateral pelvic and back pain and should prompt STI screening.

When Back Pain Does Not Improve

Acute lower back pain typically improves within 4 to 6 weeks with conservative management including analgesia, gentle movement, and physiotherapy. Pain that persists beyond 6 weeks, is progressively worsening, or is associated with any of the red flags above warrants formal medical review. A private GP appointment at The Vesey can organise investigation — including blood tests, urinalysis, and imaging if appropriate — and refer to the appropriate specialist without NHS waiting times.

Private Back Pain Assessment at The Vesey

The Vesey Private Hospital in Sutton Coldfield offers private GP consultations, specialist orthopaedic and musculoskeletal assessments, blood testing, and imaging referrals for patients with lower back pain. Our clinicians can assess, investigate, and refer appropriately — including to our orthopaedic surgery and gastroenterology teams. No GP referral is required. Book a private GP appointment online or call 0121 387 3727.

Frequently Asked Questions

What causes lower left back pain?

The most common causes are musculoskeletal — muscle strain, facet joint irritation, or a lumbar disc problem. Other causes include kidney conditions (kidney stones, kidney infection), gastrointestinal issues (diverticulitis), and in women, gynaecological conditions such as endometriosis or ovarian cysts.

What organ is on the left side of your back?

The left kidney sits at the back of the abdominal cavity at roughly the level of the lower ribs. The descending and sigmoid colon are also on the left side. In women, the left ovary and fallopian tube are on the left. All of these can cause left-sided back or flank pain when affected.

When should I worry about lower left back pain?

Seek urgent attention if pain is severe and sudden, accompanied by fever, associated with blood in the urine, comes with leg numbness or weakness, or involves loss of bladder or bowel control. Pain that does not improve within 4 to 6 weeks also warrants formal medical review.

Can lower left back pain be related to the kidney?

Yes — kidney stones, kidney infections, and other renal conditions can cause pain felt in the lower left back or flank. Kidney pain is typically felt higher up (under the ribs at the back) and may be accompanied by urinary symptoms, fever, or blood in the urine.

How is lower left back pain treated?

Treatment depends on the cause. Musculoskeletal back pain is typically managed with analgesia, gentle activity, and physiotherapy. Kidney stones may require urological intervention. Specific conditions such as endometriosis or diverticulitis require specialist management. A private GP assessment can identify the cause and direct the right treatment pathway.