Coding and coverage · ICD-10-CM
T65.824 Toxic effect of harmful algae and algae toxins, undetermined
This code needs a 7th character (use X as a placeholder for missing characters).
7th character codes
Instructional notes
Chapter 19
Excludes2Not included here: the patient may have both; report both when both are present.
Use additional codeAdd a second code for the full picture.
- code to identify any retained foreign body, if applicable (Z18.-)
Notes
- Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
- The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.
T65
7th charactersThe appropriate 7th character is to be added to each code from category T65
- A initial encounter
- D subsequent encounter
- S sequela
T65.82
Inclusion terms
- 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
Chapter 19: Injury, poisoning and certain other consequences of external causes · T07-T88 Injury, poisoning and certain other consequences of external causes (T07-T88)
Source: ICD-10-CM FY 2027 code descriptions and tabular list (CMS and CDC National Center for Health Statistics), effective 2026-10-01 through 2027-09-30 · CMS ICD-10 files. HCC mapping: CMS-HCC V28, payment year 2027. As of 2026-11-04.
Coverage and payment depend on the claim details; confirm with the Medicare Administrative Contractor.