T66

Billable

ChapterS00–T88

Rankcategory

Official Description

Radiation sickness, unspecified

Metadata & Insights

•2026 ICD-10-CM Edition - Effective October 1, 2025.
•Billable/specific code (valid for reimbursement).
•Chapter 19: Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88).

CH19 Parent Instructions

Excludes2(Not included here)

birth trauma (P10-P15)
obstetric trauma (O70-O71)

Use Additional Code

code to identify any retained foreign body, if applicable (Z18.-)

T66-T78 Parent Instructions

Code Also

, if applicable, place of occurrence, such as:
highway rest stop (Y92.523)
school (private) (public) (state) as the place of occurrence of the external cause (Y92.21-)
service areas as the place of occurrence of the external cause (Y92.52-)
single-family non-institutional (private) house as the place of occurrence of the external cause (Y92.01-)
transport vehicle as the place of occurrence of the external cause (Y92.81-)

Instructional Notes

Excludes1(Not coded here)

specified adverse effects of radiation, such as:
burns (T20-T31)
leukemia (C91-C95)
radiation gastroenteritis and colitis (K52.0)
radiation pneumonitis (J70.0)
radiation related disorders of the skin and subcutaneous tissue (L55-L59)
sunburn (L55.-)

Clinical Hierarchy

CH19Injury, poisoning and certain other consequences of external causes (S00-T88)

T66-T78Other and unspecified effects of external causes (T66-T78)

T66Radiation sickness, unspecified

Applicable Ancestor Context

The following parent sections contain instructions or notes that apply to T66:

blockT66-T78

Other and unspecified effects of external causes (T66-T78)

View context instructions

chapterCH19

Injury, poisoning and certain other consequences of external causes (S00-T88)

View context instructions

Alphabetic Index Mentions

These are Diagnosis Index lookup paths that route to T66. Use them as entry terms for search, then confirm final coding instructions in the Tabular List and notes above.

7 raw paths

Effect, adverse3 unique routes

infrared (radiation) (rays) NOS→T66

radiation (diagnostic) (infrared) (natural source) (therapeutic) (ultraviolet) (X-ray) NOS→T66

ultraviolet (radiation) (rays) NOS→T66

Irradiation effects, adverse1 unique routes

Direct index entry→T66

Radiation2 unique routes

effects NOS→T66

sickness NOS→T66

Sickness1 unique routes

radiation→T66