ICD-10 Code G35.B1 – Active primary progressive multiple sclerosis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G35.B1 – Active primary progressive multiple sclerosis
What it is
This code identifies primary progressive multiple sclerosis with active disease. Use it when the record shows a progressive MS course and current inflammatory activity or relapses.
Clinical signs
Clinical features vary; refer to documentation. Typical findings include steadily worsening neurologic impairment, such as gait difficulty, weakness, spasticity, sensory change, or balance problems.
When to use this code
Use G35.B1 when the provider documents active primary progressive multiple sclerosis, active PPMS, or progressive MS with current activity. The chart should support both the primary progressive course and the active status. If the note only says multiple sclerosis or progressive disease without activity, check documentation.
Do not use for
Do not use this code for relapsing-remitting MS, secondary progressive MS, or inactive primary progressive MS. If the subtype or activity is unclear, do not assume G35.B1.
Coding tip
Confirm both elements in the assessment: primary progressive subtype and active disease status.