X31
Exposure to excessive natural cold
X31 is a non-billable ICD-10-CM code category for exposure to excessive natural cold. Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. A 7th character is required to complete the code. Its coding notes include 3 Excludes1 entries.
7th character
Category X31 requires a 7th character. X31 has only 3 characters, so a placeholder X fills the empty positions.
Guidelines tip
From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.
An external cause code is never a principal or first-listed diagnosis. Its 7th character is assigned for each encounter and should match the injury or condition code.
Excludes1
Not coded here. The listed conditions generally should not be reported together.
Inclusion terms
Conditions classified to this code.
- Excessive cold as the cause of chilblains NOS
- Excessive cold as the cause of immersion foot or hand
- Exposure to cold NOS
- Exposure to weather conditions
Notes
Also from chapter/block level (1 note)
- This chapter permits the classification of environmental events and circumstances as the cause of injury, and other adverse effects. Where a code from this section is applicable, it is intended that it shall be used secondary to a code from another chapter of the Classification indicating the nature of the condition. Most often, the condition will be classifiable to Chapter 19, Injury, poisoning and certain other consequences of external causes (S00-T88). Other conditions that may be stated to be due to external causes are classified in Chapters I to XVIII. For these conditions, codes from Chapter 20 should be used to provide additional information as to the cause of the condition.