ICD-10 Code G47.429 – Narcolepsy in conditions classified elsewhere without cataplexy (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G47.429 – Narcolepsy in conditions classified elsewhere without cataplexy
What it is
This code identifies narcolepsy that occurs as a result of another medical condition, without cataplexy. Use it when the record shows narcoleptic sleep attacks or excessive daytime sleepiness tied to an underlying disorder.
Clinical signs
Clinical features vary; refer to documentation. Common findings include irresistible daytime sleepiness and sudden sleep episodes, while cataplexy is not present.
When to use this code
Use G47.429 when the provider documents narcolepsy secondary to another condition and specifically notes no cataplexy. This is appropriate when the chart links the sleep disorder to an underlying disease, injury, or other classified condition. Check documentation if the cause is not clearly stated.
Do not use for
Do not use this code for narcolepsy with cataplexy or when narcolepsy is not documented as due to another condition. If the record does not support the secondary cause, check documentation.
Coding tip
Verify both the absence of cataplexy and the documented underlying condition before assigning G47.429.