M54.42 – Lumbago with sciatica, left side

Learn about M54.42 ICD-10 code for lumbago with sciatica on the left side, including its billability, clinical features, and more.

By Audrey Liz Perez on Jul 16, 2025.

Fact Checked by Karina Jimenea.

Use Code

M54.42 diagnosis code: Lumbago with sciatica, left side

The ICD-10-CM code M54.42 denotes lumbago with sciatica affecting the left side. This condition involves low back pain (lumbago) accompanied by sciatic nerve pain that radiates down the left lower extremity, often following the path of the nerve from the lumbar spine through the buttock and into the leg.

Clinicians should evaluate the patient’s medical history, the presence of acute or chronic low back pain, and related symptoms like muscle weakness or numbness in the left leg. Accurate use of the M54.42 diagnosis code is important for physical therapy practice, rehab therapists, and other providers treating low back pain patients through non-surgical and surgical options.

Is M54.42 billable?

Yes, M54.42 is a billable code accepted for reimbursement purposes.

Clinical information

Lumbago with sciatica on the left side, classified under ICD-10-CM code M54.42, refers to low back pain radiating through the sciatic nerve into the left leg. This condition often stems from mechanical or structural problems in the lumbar spine, such as herniated discs, intervertebral disc degeneration, or spinal stenosis, which lead to nerve root compression, causing nerve root pain.

Patients typically report lower back pain, accompanied by numbness, tingling, or muscle weakness in the left lower extremity. Symptoms may appear suddenly like acute low back pain, or persist for weeks or months (chronic), depending on the severity and underlying cause.

Diagnosis includes a thorough patient history, physical examination, and imaging studies like MRI or CT scans to evaluate the lumbar region. Treatment options range from care at a physical therapy clinic and medications to surgical intervention in more severe or refractory cases.

Synonyms include

Left lumbago w sciatica
Low back pain co-occurrent and due to bilateral sciatica
Low back pain with bilateral sciatica
Low back pain with left sciatica
Lumbago with left sided sciatica
Lumbago with right sided sciatica

Other ICD-10 codes commonly used for back pain

M54.30: Sciatica, unspecified side
M51.360: Other intervertebral disc degeneration, lumbar region with discogenic back pain only
M51.362: Other intervertebral disc degeneration, lumbar region with discogenic back pain and lower extremity pain
M51.37: Other intervertebral disc degeneration, lumbosacral region
M54.41: Lumbago with sciatica, right side
M54.50: Low back pain, unspecified

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