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ICD-10-CM 2027 diagnosis code

T65.82Toxic effect of harmful algae and algae toxins

Not billable — use a more specific codeRequires 7th character

T65.82 is a header code, so it can't be reported by itself. Choose one of the 4 more specific codes beneath it and add the required 7th character.

Looking up by condition? See ICD-10 code for Red tide.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About T65.82

T65.82 is the ICD-10-CM diagnosis code for toxic effect of harmful algae and algae toxins. It belongs to category T65 (toxic effect of other and unspecified substances), block T51-T65 (toxic effects of substances chiefly nonmedicinal as to source) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is a header code, so it can't be reported by itself; one of its 4 subcodes must be used instead.

Within T65.8 (toxic effect of other specified substances), T65.82 is specifically for toxic effect of harmful algae and algae toxins. Related codes cover latex (T65.81), fiberglass (T65.83), xylazine (T65.84), medetomidine (T65.85) and other specified substances (T65.89).

Codes in this range require a 7th character: A for initial encounter, D for subsequent encounter and S for sequela. Use placeholder "X" characters to fill any empty positions before the 7th character.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

7th character

The appropriate 7th character is to be added to each code from category T65

  • Ainitial encounter
  • Dsubsequent encounter
  • Ssequela

Coding notes

Applicable toConditions and synonyms classified to this code
  • Toxic effect of (harmful) algae bloom NOS
  • Toxic effect of blue-green algae bloom
  • Toxic effect of brown tide
  • Toxic effect of cyanobacteria bloom
  • Toxic effect of Florida red tide
  • Toxic effect of pfiesteria piscicida
  • Toxic effect of red tide

Notes that apply from higher levels

Instructions written at a parent level also apply to T65.82.

Broader instructions also apply from T51-T65 Toxic effects of substances chiefly nonmedicinal as to source and Chapter 19: Injury, poisoning and certain other consequences of external causes.

Alphabetic index entries

2 entries

Terms in the official ICD-10-CM index that lead to T65.82.

Codes whose notes reference T65.82

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about T65.82

Is T65.82 billable?

No. T65.82 is a header code. Report one of its more specific subcodes instead.