---
title: "ICD-10-CM G47.421: Narcolepsy in conditions classified… | BillingBrief"
description: "ICD-10-CM code G47.421: Narcolepsy in conditions classified elsewhere with cataplexy. Category, related codes, and the official source, in plain English."
canonical: "https://billingbrief.com/icd10/g47.421/"
language: "en"
---

# G47.421 Narcolepsy in conditions classified elsewhere with cataplexy

ICD-10-CM · [CMS code reference](#source)

**Official ICD-10-CM description:** Narcolepsy in conditions classified elsewhere with cataplexy

## Coding notes

From the ICD-10-CM FY2027 (effective October 1, 2026) tabular list. Notes on a parent code or category apply here too.

### Excludes2

Not part of this code, but both can be coded when both are documented.

-   nightmares ([F51.5](https://billingbrief.com/icd10/f51.5/))
-   nonorganic sleep disorders (F51.-)
-   sleep terrors ([F51.4](https://billingbrief.com/icd10/f51.4/))
-   sleepwalking ([F51.3](https://billingbrief.com/icd10/f51.3/))

### Code first

Code the underlying condition first, then this code.

-   underlying condition

## Related codes

-   [`G47.37` Central sleep apnea in conditions classified elsewhere ICD-10-CM](https://billingbrief.com/icd10/g47.37/)
-   [`G47.39` Other sleep apnea ICD-10-CM](https://billingbrief.com/icd10/g47.39/)
-   [`G47.411` Narcolepsy with cataplexy ICD-10-CM](https://billingbrief.com/icd10/g47.411/)
-   [`G47.419` Narcolepsy without cataplexy ICD-10-CM](https://billingbrief.com/icd10/g47.419/)
-   [`G47.429` Narcolepsy in conditions classified elsewhere without cataplexy ICD-10-CM](https://billingbrief.com/icd10/g47.429/)
-   [`G47.50` Parasomnia, unspecified ICD-10-CM](https://billingbrief.com/icd10/g47.50/)
-   [`G47.51` Confusional arousals ICD-10-CM](https://billingbrief.com/icd10/g47.51/)
-   [`G47.52` REM sleep behavior disorder ICD-10-CM](https://billingbrief.com/icd10/g47.52/)

## Common questions

### Is G47.421 a billable code?

Yes. G47.421 is a billable ICD-10-CM code in the ICD-10-CM FY2027 (effective October 1, 2026) code set.

## From the source

Official description from [CMS](https://www.cms.gov/medicare/coding-billing/icd-10-codes).
ICD-10-CM FY2027 (effective October 1, 2026).

Code set

ICD-10-CM

Category

G47 Sleep disorders

Chapter

Diseases of the nervous system

Billable

Yes

Educational reference only. Not medical, legal, or billing advice. Always check the current official code set and payer policy before you bill. [About BillingBrief and our sources](https://billingbrief.com/about/).