ICD-10-CM T66: Radiation sickness, unspecified

ICD-10-CM Diagnosis Code (2025)

Official Description for T66

Radiation sickness, unspecified

Coding Notes & Guidelines for T66

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.-)
7th Character Guidance

The appropriate 7th character is to be added to code T66

7th Character Definitions
  • A: initial encounter
  • D: subsequent encounter
  • S: sequela

About ICD-10-CM Code T66 (Radiation sickness)

ICD-10-CM code T66 is a billable or specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes. The 2025 edition of ICD-10-CM T66 became effective on October 1, 2024.

This page provides detailed information about T66 - Radiation sickness, unspecified. It includes common terminology, coding guidelines such as "Includes," "Excludes1," and "Excludes2" notes, and information on required 7th characters. Utilizing this information correctly is essential for accurate medical coding and claims submission for conditions like Radiation sickness related to unspecified.