2027 ICD-10-CM Diagnosis Code T65.91XAToxic effect of unspecified substance, accidental (unintentional), initial encounter
T65.91XA is a billable ICD-10-CM diagnosis code for toxic effect of unspecified substance, accidental (unintentional), initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 917 through 918. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under External cause codes: intent of injury, accidental/unintentional; External cause codes: poisoning by non-drug; and Toxic effects, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Accidental bismuth compound poisoning
- Accidental ingestion of toxic substance
- Accidental poisoning by household agents
- Acne of external chemical origin
- Acquired bronchiectasis
- Acute chemical bronchitis
- Acute conjunctivitis caused by chemical
- Acute conjunctivitis of bilateral eyes caused by chemical substance
- Acute conjunctivitis of left eye caused by chemical substance
- Acute conjunctivitis of right eye caused by chemical substance
- Acute exogenous lipoid pneumonitis
- Acute intoxication
- Acute phototoxic reaction
- Acute renal cortical necrosis
- Acute toxic cicatrizing conjunctivitis
- Acute toxic conjunctivitis
- Acute toxic tracheobronchitis
- Acute tracheitis
- Acute tracheobronchitis
- Acute tubular necrosis
- Adverse effect of exposure to industrial hazardous material
- Aerosol air freshener causing toxic effect
- Air freshener causing toxic effect
- Allergic reaction to chemical
- Anagen effluvium
- Bilateral acute conjunctivitis
- Bismuth compound poisoning
- Bronchiectasis due to aspiration of toxic substance
- Bronchiectasis due to inhalation of toxic substance
- Bronchitis caused by chemical
- Burn and corrosion of hip and lower limb, except ankle and foot
- Burn erythema of chest wall
- Burn of abdominal wall
- Burn of ankle and foot
- Burn of breast
- Burn of buttock
- Burn of chin
- Burn of conjunctival sac
- Burn of conjunctival sac of left eye
- Burn of conjunctival sac of right eye
- Burn of cornea of left eye
- Burn of cornea of right eye
- Burn of dorsum of left hand
- Burn of dorsum of right hand
- Burn of esophagus
- Burn of forehead
- Burn of inguinal region
- Burn of larynx
- Burn of larynx and/or trachea
- Burn of left ankle
- Burn of left axillary region
- Burn of left elbow region
- Burn of left eye proper
- Burn of left eyelid
- Burn of left forearm
- Burn of left knee region
- Burn of left lower leg
- Burn of left ocular adnexa
- Burn of left palm
- Burn of left shoulder
- Burn of left thigh
- Burn of left thumb
- Burn of left upper arm
- Burn of left wrist
- Burn of lower back
- Burn of male genitalia
- Burn of nose
- Burn of right ankle
- Burn of right axillary region
- Burn of right elbow region
- Burn of right eye proper
- Burn of right eyelid
- Burn of right forearm
- Burn of right knee region
- Burn of right lower leg
- Burn of right ocular adnexa
- Burn of right palm
- Burn of right shoulder
- Burn of right thigh
- Burn of right thumb
- Burn of right upper arm
- Burn of right wrist
- Burn of scalp
- Burn of throat
- Burn of toe of left foot
- Burn of toe of right foot
- Burn of vagina
- Burning caused by caustic organic chemical
- Carcinogen effect
- Cerebellar ataxia caused by chemical
- Chemical burn injury to conjunctiva
- Chemical burn of abdominal wall
- Chemical burn of axilla
- Chemical burn of back of left hand
- Chemical burn of back of right hand
- Chemical burn of breast
- Chemical burn of buttock
- Chemical burn of cheek
- Chemical burn of elbow
- Chemical burn of esophagus
- Chemical burn of eyelid
- Chemical burn of face
- Chemical burn of female genitalia
- Chemical burn of forehead
- Chemical burn of gastrointestinal tract
- Chemical burn of hand
- Chemical burn of head
- Chemical burn of inguinal region
- Chemical burn of internal organ
- Chemical burn of larynx
- Chemical burn of left ankle
- Chemical burn of left axilla
- Chemical burn of left conjunctival sac
- Chemical burn of left cornea
- Chemical burn of left elbow
- Chemical burn of left eye
- Chemical burn of left eyelid
- Chemical burn of left foot
- Chemical burn of left forearm
- Chemical burn of left hand
- Chemical burn of left knee
- Chemical burn of left lower leg
- Chemical burn of left palm
- Chemical burn of left shoulder
- Chemical burn of left thigh
- Chemical burn of left thumb
- Chemical burn of left toe
- Chemical burn of left upper arm
- Chemical burn of left wrist
- Chemical burn of lip
- Chemical burn of lower back
- Chemical burn of male genitalia
- Chemical burn of mouth
- Chemical burn of neck
- Chemical burn of nose
- Chemical burn of pharynx
- Chemical burn of respiratory tract
- Chemical burn of right ankle
- Chemical burn of right axilla
- Chemical burn of right conjunctival sac
- Chemical burn of right cornea
- Chemical burn of right elbow
- Chemical burn of right eye
- Chemical burn of right eyelid
- Chemical burn of right foot
- Chemical burn of right forearm
- Chemical burn of right hand
- Chemical burn of right knee
- Chemical burn of right lower leg
- Chemical burn of right palm
- Chemical burn of right shoulder
- Chemical burn of right thigh
- Chemical burn of right thumb
- Chemical burn of right toe
- Chemical burn of right upper arm
- Chemical burn of right wrist
- Chemical burn of scalp
- Chemical burn of shoulder
- Chemical burn of skin
- Chemical burn of thumb
- Chemical burn of toe
- Chemical burn of vagina
- Chemical burn of wrist
- Chemical colitis
- Chemical cranial nerve injury
- Chemical esophagitis
- Chemical hematuria
- Chemical injury to cornea
- Chemical keratitis
- Chemical meningitis
- Chemical-aggravated angioedema-urticaria
- Chemical-induced asthma
- Chemical-induced dermatological disorder
- Chemically-induced hypomelanosis
- Chemically-induced malabsorption
- Chemically-induced proctitis
- Chronic chemical respiratory disease
- Chronic exogenous lipoid pneumonitis
- Chronic follicular conjunctivitis
- Chronic myocardial disorder caused by chemical or external agent
- Chronic poisoning
- Chronic toxic cicatrizing conjunctivitis
- Chronic toxic follicular conjunctivitis
- Chronic toxic interstitial nephritis
- Cicatrizing conjunctivitis
- Cognitive impairment due to toxicity of substance
- Correction fluid causing toxic effect
- Corrosion of 2nd degree of hip and lower limb, except ankle and foot
- Corrosion of ankle and foot
- Corrosion of esophagus
- Corrosion of first degree of ankle and foot
- Corrosion of first degree of head and neck
- Corrosion of first degree of hip and lower limb,except ankle and foot
- Corrosion of first degree of trunk
- Corrosion of first degree of wrist and hand
- Corrosion of head and neck
- Corrosion of larynx and/or trachea
- Corrosion of second degree of ankle and foot
- Corrosion of second degree of head and neck
- Corrosion of second degree of shoulder and upper limb, except wrist and hand
- Corrosion of second degree of trunk
- Corrosion of second degree of wrist and hand
- Corrosion of third degree of ankle and foot
- Corrosion of third degree of head and neck
- Corrosion of third degree of hip and lower limb, except ankle and foot
- Corrosion of wrist and hand
- Crayon causing toxic effect
- Dabbing
- Damp-proof liquid causing toxic effect
- Diarrhea caused by ingestion of unabsorbable substances
- Drug ototoxicity - deafness
- Duodenitis caused by chemical
- Environmental toxin-induced male infertility
- Epidermal burn of back
- Epidermal burn of breast
- Epidermal burn of chin
- Epidermal burn of ear
- Epidermal burn of neck
- Epidermal burn of nose
- Epidermal burn of scalp
- Epidermal burn of wrist
- Epidermal burn of wrist and hand
- Exogenous lipoid pneumonitis
- Fetal disorder caused by substance transmitted via placenta
- Fire extinguisher material causing toxic effect
- Fire retardant causing toxic effect
- Firelighter causing toxic effect
- Focal segmental glomerulosclerosis
- Focal segmental glomerulosclerosis caused by substance
- Full thickness burn of forearm
- Full thickness burn of head and neck
- Full thickness burn of left forearm
- Full thickness burn of neck
- Full thickness burn of right forearm
- Full thickness chemical burn of forearm
- Full thickness chemical burn of left forearm
- Full thickness chemical burn of right forearm
- Gardening product causing toxic effect
- Gastric ulcer caused by chemical
- Hair shaft damage by chemical
- Idiopathic lipoid pneumonia
- Inflammatory and toxic neuropathy
- Ingestion of foreign material
- Ingestion of toxic substance
- Inhalation injury
- Inhalation injury due to chemical
- Inhalation of substance
- Injury due to chemical exposure
- Injury of conjunctiva of left eye
- Injury of conjunctiva of right eye
- Injury to respiratory system due to inhalation of particulate matter
- Intoxication
- Keratitis due to trauma
- Local toxic nerve damage
- Lung disease due to external agents
- Movement disorder due to toxicity of substance
- Myelopathy due to toxicity of substance
- Myocarditis due to chemical agent
- Nail changes associated with systemic disease
- Nail damage caused by chemical agents
- Nail damage from external agent
- Nail dystrophy caused by chemical
- Neuropathy caused by chemical substance
- Neuropathy caused by organic substance
- Neurotoxicity
- Non-infective diarrhea
- Non-melanin pigmentation caused by exogenous substance
- Occupational acne
- Occupational phototoxic reaction to skin contact with exogenous photoactive agent
- Occupational toxicoderma
- Oil acne
- Onycholysis
- Onycholysis caused by chemical
- Osmotic diarrhea
- Ototoxic degeneration of cochlea
- Ototoxicity
- Ototoxicity - deafness
- Ototoxicity - labyrinthine
- Partial thickness burn of left foot
- Partial thickness burn of right foot
- Partial thickness burn of shoulder
- Partial thickness burn of wrist
- Pericarditis caused by toxin
- Peripheral neuropathy caused by toxin
- Peripheral neuropathy of upper limb caused by toxin
- Pet animal-care product causing toxic effect
- Photographic material causing toxic effect
- Phototoxic reaction to topical chemical
- Pigment nephropathy
- Plaster of Paris injury to skin
- Pneumonitis caused by inhaled substance
- Pneumonitis caused by solids
- Pneumonitis due to inhaled liquid
- Poisoning
- Porphyria caused by toxic effect of substance
- Pulmonary arterial hypertension induced by toxin
- Rust remover causing toxic effect
- Sealant causing toxic effect
- Second degree chemical burn of foot
- Second degree chemical burn of left foot
- Second degree chemical burn of right foot
- Secondary porphyria
- Self-administered accidental poisoning
- Shoe care product causing toxic effect
- Silo-fillers' disease
- Skin reaction to vesicant poison
- Small vessel pulmonary hypertension
- Solitary pulmonary hypertension
- Substance-induced ataxia
- Sulfite-induced asthma
- Superficial corrosion of back
- Superficial corrosion of breast
- Superficial corrosion of cheek
- Superficial corrosion of chest wall
- Superficial corrosion of chin
- Superficial corrosion of ear
- Superficial corrosion of lip
- Superficial corrosion of neck
- Superficial corrosion of nose
- Superficial corrosion of scalp
- Superficial injury of chin
- Toxic acute tubular necrosis
- Toxic amblyopia
- Toxic anagen effluvium
- Toxic cardiomyopathy
- Toxic chorea
- Toxic confusional state
- Toxic deafness
- Toxic dementia
- Toxic dilatation of intestine
- Toxic dilated cardiomyopathy
- Toxic disorder of refraction AND/OR accommodation
- Toxic dystonia
- Toxic emphysema
- Toxic enteritis of small intestine
- Toxic gastritis
- Toxic keratoconjunctivitis
- Toxic leukoencephalopathy
- Toxic optic neuropathy
- Toxic polyneuropathy
- Toxic radiculopathy
- Toxic retinopathy
- Toxic tremor
- Toxicoderma
- Toxin-induced bronchiectasis
- Toxin-induced parkinsonism
- Ulcer of duodenum caused by chemical
- Ulcer of esophagus caused by ingestion of corrosive chemical
- Vulvitis caused by chemical
- Wallpaper stripper causing toxic effect
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Toxic effect of other and unspecified substances (T65). Use the following options for the applicable episode of care:
- A - initial encounter
- D - subsequent encounter
- S - sequela
Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027, published by CMS and the National Center for Health Statistics.
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to T65.91XA: its own notes plus those printed at T65, block T51-T65, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- contact with and (suspected) exposure to toxic substances (Z77.-)
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code to identify any retained foreign body, if applicable (Z18.-)
Notes
General instructions on how these codes are used.
- 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.
7th Character
Every code in the category takes a 7th character from the listed values, with the placeholder X filling any empty positions before it.
- The appropriate 7th character is to be added to each code from category T65
- Ainitial encounter this code
- Dsubsequent encounter
- Ssequela
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Table of Drugs and ChemicalsClinical
Substances in the Table of Drugs and Chemicals that reference this code family. Always confirm in the Tabular List before coding.
| Substance | Accidental | Self-harm | Assault | Undetermined | Adverse Effect | Underdosing |
|---|---|---|---|---|---|---|
| Aerosol spray NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Agricultural agent NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Air contaminant (s), source/type NOS | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Antifreeze | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Bismuth salts::nonmedicinal (compounds) NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Chemical substance NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Horticulture agent NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Ingested substance NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Liquid::substance | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Poison NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Solid substance | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Spray (aerosol) | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
Patient EducationClinical
Poisoning
A poison is any substance that is harmful to your body. You might swallow it, inhale it, inject it, or absorb it through your skin. Any substance can be poisonous if too much is taken. Poisons can include:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T65.91XA to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T65.91XAOverview
Is T65.91XA a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report toxic effect of unspecified substance, accidental (unintentional), initial encounter on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What does the 7th character A in T65.91XA mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for toxic effect of unspecified substance, accidental (unintentional), such as an emergency visit or first evaluation.
What MS-DRG does T65.91XA group to?
When toxic effect of unspecified substance, accidental (unintentional), initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 918, 917, with relative weights from 0.8716 to 1.5698 depending on complications. Higher weights mean higher Medicare reimbursement.
Can T65.91XA be reported with a code from Z77?
Not as a rule. The Excludes1 note at block T51-T65, which applies to T65.91XA, lists "contact with and (suspected) exposure to toxic substances (Z77.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What is the ICD-9 equivalent of T65.91XA?
Under the General Equivalence Mappings, toxic effect of unspecified substance, accidental (unintentional), initial encounter converts to ICD-9-CM 989.9 (tox eff nonmed subst NOS) and E866.8 (acc pois-solid/liq NEC). The mapping is approximate, so confirm the match fits the documentation.
