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T65.822A ICD-10-CM Code: Toxic effect of harmful algae and algae toxins, intentional self-harm, initial encounter

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

7th character
Required — see the character table on this page
Tabular directives
1 Excludes1 · 4 use-additional codes
Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 58 · RxHCC V08 category 132

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

  • MS-DRG 917 — POISONING AND TOXIC EFFECTS OF DRUGS WITH MCC (MDC 21)
  • MS-DRG 918 — POISONING AND TOXIC EFFECTS OF DRUGS WITHOUT MCC (MDC 21)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 155 — Major Depression, Moderate or Severe, without Psychosis

Other models: CMS-HCC V22 HCC 58 · RxHCC V08 HCC 132

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for T65.822A in the official ICD-10-CM tabular list, quoted as published.

Notes without a marker are published on T65.822A itself; “inherited from” names the category or block whose note applies here.

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Source: inherited from T51-T65

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code(s):
  • for all associated manifestations of toxic effect, such as: respiratory conditions due to external agents (J60-J70)
  • personal history of foreign body fully removed (Z87.821)
  • to identify any retained foreign body, if applicable (Z18.-)

Source: inherited from T51-T65

7th Character Guide

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

  • A — initial encounter (this page’s code)
  • D — subsequent encounter
  • S — sequela

How the encounter character is assigned. “Initial encounter” means the patient is receiving active treatment for the condition — it is not limited to the first visit, and a different or new provider giving active treatment still assigns it. “Subsequent encounter” covers care during the healing or recovery phase after active treatment. “Sequela” is for complications or conditions that arise as a direct result of the original condition.

ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.19.a (paraphrased by MedCoder).

Variant codes in this family

T65.822A, T65.822D, T65.822S

Character meanings are CMS's official 7th-character extensions for this family, as carried in each variant code's official description; variant codes are registry rows. The explanation of how the encounter character is assigned is MedCoder editorial, distinct from the official content above it.

Coder workflow for T65.822A

MedCoder structured workflow — derived from this code’s own official record

Before you code T65.822A

  1. A 7th character is required in this family. Confirm the documented encounter: initial (active treatment), subsequent (healing or recovery phase), or sequela. This page’s code carries “A”. “Initial” means active treatment, not the first visit (Guidelines I.C.19.a).

    See the 7th Character Guide · Guide: 7th characters: initial, subsequent, sequela →

  2. Confirm whether the documentation describes a poisoning, an adverse effect of a correctly prescribed and administered drug, an underdosing, or a toxic effect, and the intent where the record states it: the Table of Drugs and Chemicals separates these by column, and the sequencing differs for each. Poisoning, adverse effect and underdosing guidelines (Guidelines I.C.19.e).

    See the Table of Drugs and Chemicals entries · Guide: Poisoning vs adverse effect vs underdosing →

  3. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with T65.822A. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the documentation support a condition named in T65.822A’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewZ77

  2. Is the encounter phase documented — active treatment, healing or recovery, or a sequela?
    Yes → Assign the matching 7th character; the variant codes are in the 7th Character Guide.
    No → The code is invalid without its 7th character — query for the missing element.

Consider T65.822A. Then work the Use Additional Code note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
Encounter type
Active treatment, healing or recovery phase, or sequela — the basis of the 7th character (Guidelines I.C.19.a).
The conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.
External cause, place and activity
For the external cause codes reported with the injury or poisoning, where documented (Guidelines I.C.20.a).

Official instructions as workflow

  • Excludes1 — check before selecting T65.822A(1 note)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with T65.822A: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareZ77

    See the official tabular notes · Guidelines I.A.12.a

  • Use Additional Code — after identifying T65.822A(4 notes)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with T65.822A when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    ReviewZ87.821, Z18

    See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: Both the condition T65.822A describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewZ77

Documentation: The patient returns during the healing or recovery phase after active treatment of the same condition.

Coding question: Which 7th character applies?

Path: Review the official 7th-character definitions for this family in the 7th Character Guide.

Reason: “Initial encounter” means active treatment, not the first visit; care during recovery takes “subsequent encounter”, and a complication arising from the original condition takes “sequela” (Guidelines I.C.19.a).

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with T65.822A?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

ReviewZ87.821, Z18

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Code Overview

Toxic effect of harmful algae and algae toxins, intentional self-harm, initial encounter is a billable ICD-10-CM diagnosis code (T65.822A).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Associated Substances (1)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Substances from the official ICD-10-CM Table of Drugs and Chemicals that map to this code.

  • Algae (harmful) (toxin)

Official Coding Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Verbatim excerpts from the ICD-10-CM Official Guidelines for Coding and Reporting (CMS/NCHS) that govern this code.

Chapter 19: Injury, poisoning, and certain other consequences of external causes (S00-T88)

e. Adverse Effects, Poisoning, Underdosing and Toxic Effects Codes in categories T36-T65 are combination codes that include the substance that was taken as well as the intent. No additional external cause code is required for poisonings, toxic effects, adverse effects and underdosing codes.

Chapter 19: Injury, poisoning, and certain other consequences of external causes (S00-T88)

(d) Toxic Effects W hen a harmful substance is ingested or comes in contact with a person, this is classified as a toxic effect. The toxic effect codes are in categories T51-T65. When coding a toxic effect, assign the toxic effect code first, followed by codes for all associated manifestations of the toxic effect.

Decision Points

The directives on this code's own record, as a pre-claim checklist.

  1. A 7th character applies in this family. Confirm the documented encounter matches the character assigned. See the official 7th-character definitions and this code’s variants
  2. 4 Use Additional Code instructions — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
  3. 1 Excludes1 entry — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

Verify Before Coding

  • No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name T65.822A or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: T61 — Toxic effect of noxious substances eaten as seafood (via T65.82.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 11 Excludes2 notes across 2 chapters: T80 — Complications following infusion, transfusion and therapeutic injection (via T65.-), T80-T88 — Complications of surgical and medical care, not elsewhere classified (T80-T88) (via T65.-), T81 — Complications of procedures, not elsewhere classified (via T65.-), T82 — Complications of cardiac and vascular prosthetic devices, implants and grafts (via T65.-), T83 — Complications of genitourinary prosthetic devices, implants and grafts (via T65.-), T84 — Complications of internal orthopedic prosthetic devices, implants and grafts (via T65.-), T85 — Complications of other internal prosthetic devices, implants and grafts (via T65.-), T86 — Complications of transplanted organs and tissue (via T65.-), T87 — Complications peculiar to reattachment and amputation (via T65.-), T88 — Other complications of surgical and medical care, not elsewhere classified (via T65.-), Z77 — Other contact with and (suspected) exposures hazardous to health (via T65.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Referenced by 68 Code First instructions across 14 chapters: D61.2 — Aplastic anemia due to other external agents (via T65.-), D64.2 — Secondary sideroblastic anemia due to drugs and toxins (via T65.-), E03.2 — Hypothyroidism due to medicaments and other exogenous substances (via T65.-), E09 — Drug or chemical induced diabetes mellitus (via T65.-), F02 — Dementia in other diseases classified elsewhere (via T65.-), G21.2 — Secondary parkinsonism due to other external agents (via T65.-), G62.2 — Polyneuropathy due to other toxic agents (via T65.-), G70.1 — Toxic myoneural disorders (via T65.-), G72.2 — Myopathy due to other toxic agents (via T65.-), G92.8 — Other toxic encephalopathy (via T65.-), G92.9 — Unspecified toxic encephalopathy (via T65.-), H10.21 — Acute toxic conjunctivitis (via T65.-), H35.38 — Toxic maculopathy (via T65.-), H46.3 — Toxic optic neuropathy (via T65.-), H91.0 — Ototoxic hearing loss (via T65.-), I42.7 — Cardiomyopathy due to drug and external agent (via T65.-), J68 — Respiratory conditions due to inhalation of chemicals, gases, fumes and vapors (via T65.-), J69.1 — Pneumonitis due to inhalation of oils and essences (via T65.-), J69.8 — Pneumonitis due to inhalation of other solids and liquids (via T65.-), J70.8 — Respiratory conditions due to other specified external agents (via T65.-), +48 more.

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

Not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity.

Named in the grouper logic of 2 MS-DRGs: DRG 917 (MDC 21), DRG 918 (MDC 21).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):MBD012 — Suicidal ideation/attempt/intentional self-harm (default); EXT011 — External cause codes: natural/environment; initial encounter; EXT021 — External cause codes: intent of injury, self-harm; INJ023 — Toxic effects, initial encounter.

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same injury, other encounter phase

Same injury, coded at a different phase of treatment via the 7th character.

T65.822D — Toxic effect of harmful algae and algae toxins, intentional self-harm, subsequent encounterCompare T65.822A vs T65.822D →, T65.822S — Toxic effect of harmful algae and algae toxins, intentional self-harm, sequelaCompare T65.822A vs T65.822S →

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Major Depression, Moderate or Severe, without Psychosis) for risk-adjusted payment.

T65.0X2A — Toxic effect of cyanides, intentional self-harm, initial encounter, T65.1X2A — Toxic effect of strychnine and its salts, intentional self-harm, initial encounter, T65.212A — Toxic effect of chewing tobacco, intentional self-harm, initial encounter, T65.222A — Toxic effect of tobacco cigarettes, intentional self-harm, initial encounter, T65.292A — Toxic effect of other tobacco and nicotine, intentional self-harm, initial encounter, T65.3X2A — Toxic effect of nitroderivatives and aminoderivatives of benzene and its homologues, intentional self-harm, initial encounter, T65.4X2A — Toxic effect of carbon disulfide, intentional self-harm, initial encounter, T65.5X2A — Toxic effect of nitroglycerin and other nitric acids and esters, intentional self-harm, initial encounter, T65.6X2A — Toxic effect of paints and dyes, not elsewhere classified, intentional self-harm, initial encounter, T65.812A — Toxic effect of latex, intentional self-harm, initial encounter, T65.832A — Toxic effect of fiberglass, intentional self-harm, initial encounter, T65.842A — Toxic effect of xylazine, intentional self-harm, initial encounter, T65.892A — Toxic effect of other specified substances, intentional self-harm, initial encounter, T65.92XA — Toxic effect of unspecified substance, intentional self-harm, initial encounter, T71.112A — Asphyxiation due to smothering under pillow, intentional self-harm, initial encounter, T71.122A — Asphyxiation due to plastic bag, intentional self-harm, initial encounter, T71.132A — Asphyxiation due to being trapped in bed linens, intentional self-harm, initial encounter, T71.152A — Asphyxiation due to smothering in furniture, intentional self-harm, initial encounter, T71.162A — Asphyxiation due to hanging, intentional self-harm, initial encounter, T71.192A — Asphyxiation due to mechanical threat to breathing due to other causes, intentional self-harm, initial encounter, +350 more

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Schizophrenia, Psychosis, Except Schizophrenia, Personality Disorders; Anorexia/Bulimia Nervosa, Bipolar Disorders without Psychosis

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical categories (Suicidal ideation/attempt/intentional self-harm, External cause codes: natural/environment; initial encounter, External cause codes: intent of injury, self-harm, Toxic effects, initial encounter).

T63.711A — Toxic effect of contact with venomous marine plant, accidental (unintentional), initial encounter, T63.712A — Toxic effect of contact with venomous marine plant, intentional self-harm, initial encounter, T63.713A — Toxic effect of contact with venomous marine plant, assault, initial encounter, T63.714A — Toxic effect of contact with venomous marine plant, undetermined, initial encounter, T63.791A — Toxic effect of contact with other venomous plant, accidental (unintentional), initial encounter, T63.792A — Toxic effect of contact with other venomous plant, intentional self-harm, initial encounter, T63.793A — Toxic effect of contact with other venomous plant, assault, initial encounter, T63.794A — Toxic effect of contact with other venomous plant, undetermined, initial encounter, T65.821A — Toxic effect of harmful algae and algae toxins, accidental (unintentional), initial encounter, T65.823A — Toxic effect of harmful algae and algae toxins, assault, initial encounter, T65.824A — Toxic effect of harmful algae and algae toxins, undetermined, initial encounter, T73.0XXA — Starvation, initial encounter, T73.1XXA — Deprivation of water, initial encounter, T73.2XXA — Exhaustion due to exposure, initial encounter, T73.8XXA — Other effects of deprivation, initial encounter, T73.9XXA — Effect of deprivation, unspecified, initial encounter, T75.00XA — Unspecified effects of lightning, initial encounter, T75.01XA — Shock due to being struck by lightning, initial encounter, T75.09XA — Other effects of lightning, initial encounter, T75.20XA — Unspecified effects of vibration, initial encounter, +884 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Poisoning”; these codes share that main term but sit in a different category of the Tabular List.

A02.0 — Salmonella enteritis (food NEC, due to, salmonella, with, gastroenteritis), A02.1 — Salmonella sepsis (food NEC, due to, salmonella, with, sepsis), A02.9 — Salmonella infection, unspecified (Bacillus B), A05.0 — Foodborne staphylococcal intoxication (Staphylococcus, food), A05.1 — Botulism food poisoning (botulism), A05.2 — Foodborne Clostridium perfringens [Clostridium welchii] intoxication (food NEC, due to, Clostridium), A05.3 — Foodborne Vibrio parahaemolyticus intoxication (food NEC, due to, Vibrio, parahaemolyticus), A05.5 — Foodborne Vibrio vulnificus intoxication (food NEC, due to, Vibrio, vulnificus), A05.9 — Bacterial foodborne intoxication, unspecified (food NEC), D55.0 — Anemia due to glucose-6-phosphate dehydrogenase [G6PD] deficiency (fava bean), E87.79 — Other fluid overload (water), J70.0 — Acute pulmonary manifestations due to radiation (radiation), T56.0 — Toxic effects of lead and its compounds (lead), T61.0 — Ciguatera fish poisoning (ciguatera fish), T61.1 — Scombroid fish poisoning (scombroid fish), T61.77 — Other fish poisoning (fish, specified type NEC), T61.78 — Other shellfish poisoning (shellfish), T61.9 — Toxic effect of unspecified seafood (fish), T62.9 — Toxic effect of unspecified noxious substance eaten as food (food NEC, noxious or naturally toxic)

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Gamma-glutamyl Transferase (GGT) Test, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of T65.822A in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run T65.822A with these 17 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Excludes2 notes (11)

Referenced by Code First instructions (68)

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 155 — Major Depression, Moderate or Severe, without Psychosis [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

MDC crossing

  • MDC 21 — Injuries, Poisonings and Toxic Effects of Drugs[MDC crossing]: “Injuries, Poisonings and Toxic Effects of Drugs — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 32,029 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Drugs & chemicals

  • Algae (harmful) (toxin) — Algae (harmful) (toxin) — Poisoning, Intentional self-harm [Drug table]: “Algae (harmful) (toxin) (Poisoning, Intentional self-harm)”— CMS Table of Drugs and Chemicals · icd10cm-fy2026

Nearest codes (40)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Common coding questions

Does T65.822A require a 7th character?

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

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Coding guidelines Official source data
ICD-10-CM Official Guidelines for Coding and Reporting (FY2026), quoted by section Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Toxic effect of harmful algae and algae toxins, intentional self-harm, initial encounter

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to T65.822A in its code family, with their registry titles.

View all codes in the T65 family