T65.82
Toxic effect of harmful algae and algae toxins
T65.82 is a non-billable ICD-10-CM code header for toxic effect of harmful algae and algae toxins. Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. The more specific codes under it are T65.821 Toxic effect of harmful algae and algae toxins, accidental (unintentional); T65.822 Toxic effect of harmful algae and algae toxins, intentional self-harm; T65.823 Toxic effect of harmful algae and algae toxins, assault and T65.824 Toxic effect of harmful algae and algae toxins, undetermined. Its coding notes include a Use additional code instruction, 1 Excludes1 entry and 2 Excludes2 entries.
7th characters
Every code below needs one of these (defined at T65).
The appropriate 7th character is to be added to each code from category T65
- Ainitial encounter
- Dsubsequent encounter
- Ssequela
Guidelines tips
From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.
The 7th character depends on whether the patient is in active treatment, not on who sees the patient. An aftercare Z code is not used for injury aftercare.
T36-T65 codes already include the substance and the intent, so no additional external cause code is required. Do not code directly from the Table of Drugs and Chemicals.
Use additional code
Add the listed code as a secondary code, if known.
Also from chapter/block level (5 notes)
- code to identify any retained foreign body, if applicable (Z18.-)
Excludes1
Not coded here. The listed conditions generally should not be reported together.
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
Also from chapter/block level (2 notes)
- birth trauma (P10-P15)
- obstetric trauma (O70-O71)
Inclusion terms
Conditions 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
Also from chapter/block level (3 notes)
- When no intent is indicated code to accidental. Undetermined intent is only for use when there is specific documentation in the record that the intent of the toxic effect cannot be determined.
- 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.
Alphabetic Index terms
Terms the official Alphabetic Index lists for this code. 2 entries
More specific codes under T65.82 4
- T65.821Toxic effect of harmful algae and algae toxins, accidental (unintentional)7th char needed
- T65.822Toxic effect of harmful algae and algae toxins, intentional self-harm7th char needed
- T65.823Toxic effect of harmful algae and algae toxins, assault7th char needed
- T65.824Toxic effect of harmful algae and algae toxins, undetermined7th char needed