X31Header code — not billable

Exposure to excessive natural cold

Chapter
20. External causes of morbidity
Category
X31
Effective date
October 1, 2026

Related codes in category X31

X31.XXXAExposure to excessive natural cold, initial encounterYesX31.XXXDExposure to excessive natural cold, subsequent encounterYesX31.XXXSExposure to excessive natural cold, sequelaYes

Frequently asked questions

What is ICD-10 code X31?

X31 is an ICD-10-CM diagnosis code for Exposure to excessive natural cold.

Is X31 a billable code?

No. X31 is a category/header code, not billable on its own — use one of its more specific child codes instead.

What ICD-10-CM chapter is X31 in?

X31 falls under Chapter 20: External causes of morbidity.

When did X31 become effective?

X31 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.

What other codes are related to X31?

X31 belongs to category X31, which includes 3 other codes — see the related codes list on this page.

ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.