ICD-10 Code G35.C – Secondary progressive multiple sclerosis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G35.C – Secondary progressive multiple sclerosis
What it is
Use this code for multiple sclerosis that has entered a secondary progressive phase after an earlier relapsing course. It indicates ongoing neurologic worsening, with or without relapses.
Clinical signs
Clinical features vary; refer to documentation. Commonly, you may see steadily increasing disability, gait decline, weakness, spasticity, or worsening coordination over time.
When to use this code
Use G35.C when the provider documents secondary progressive multiple sclerosis explicitly. It may also apply when the record clearly states progressive worsening following a prior relapsing-remitting course. If the MS type is not specified, check documentation before coding.
Do not use for
Do not use this code for relapsing-remitting, primary progressive, or unspecified multiple sclerosis. If the chart only says “multiple sclerosis” without the subtype, do not assume secondary progressive disease.
Coding tip
Code the documented MS subtype exactly as stated, and query the provider if the course is unclear.