2026 ICD-10-CM Diagnosis Code T50.903APoisoning by unspecified drugs, medicaments and biological substances, assault, initial encounter
T50.903A is a billable ICD-10-CM diagnosis code for poisoning by unspecified drugs, medicaments and biological substances, assault, 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 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 917 through 918. Coders also document this condition as assault by poisoning. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under External cause codes: intent of injury, assault; External cause codes: poisoning by drug; and Poisoning by drugs, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Assault by poisoning
- Assault by poisoning by drugs or medicines
Coding GuidelinesGuidance
When coding a poisoning or reaction to the improper use of a medication (e.g., overdose, wrong substance given or taken in error, wrong route of administration), first assign the appropriate code from categories T36-T50. The poisoning codes have an associated intent as their 5th or 6th character (accidental, intentional self-harm, assault and undetermined). If the intent of the poisoning is unknown or unspecified, code the intent as accidental intent. The undetermined intent is only for use if the documentation in the record specifies that the intent cannot be determined. Use additional code(s) for all manifestations of poisonings.
The appropriate 7th character is to be added to each code from block Poisoning by, adverse effect of and underdosing of diuretics and other and unspecified drugs, medicaments and biological substances (T50). 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 2026, published by CMS and the National Center for Health Statistics.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Laminaria
a genus of brown algae in the family laminariaceae. dried pencil-like pieces may be inserted in the cervix where they swell as they absorb moisture, serving as osmotic dilators.Saccharin
flavoring agent and non-nutritive sweetener.1,4-alpha-Glucan Branching Enzyme
in glycogen or amylopectin synthesis, the enzyme that catalyzes the transfer of a segment of a 1,4-alpha-glucan chain to a primary hydroxy group in a similar glucan chain. ec 2.4.1.18.Electrophoresis, Starch Gel
electrophoresis in which a starch gel (a mixture of amylose and amylopectin) is used as the diffusion medium.Hydroxyethyl Starch Derivatives
starches that have been chemically modified so that a percentage of oh groups are substituted with 2-hydroxyethyl ether groups.Starch
any of a group of polysaccharides of the general formula (c6-h10-o5)n, composed of a long-chain polymer of glucose in the form of amylose and amylopectin. it is the chief storage form of energy reserve (carbohydrates) in plants.Starch Phosphorylase
an enzyme of the phosphorylases family that catalyzes the degradation of starch, a mixture of unbranched amylose and branched amylopectin compounds. this phosphorylase from plants is the counterpart of glycogen phosphorylase in animals that catalyzes the reaction of inorganic phosphate on the terminal alpha-1,4-glycosidic bond at the non-reducing end of glucans resulting in the release of glucose-1-phosphate.Starch Synthase
an enzyme that catalyzes the transfer of glucose from adpglucose to glucose-containing polysaccharides in 1,4-alpha-linkages. ec 2.4.1.21.
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.
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 T50.903A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T50.903AOverview
Is T50.903A a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report poisoning by unspecified drugs, medicaments and biological substances, assault, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T50.903A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for poisoning by unspecified drugs, medicaments and biological substances, assault, such as an emergency visit or first evaluation.
What MS-DRG does T50.903A group to?
When poisoning by unspecified drugs, medicaments and biological substances, assault, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of T50.903A?
Under the General Equivalence Mappings, poisoning by unspecified drugs, medicaments and biological substances, assault, initial encounter converts to ICD-9-CM 977.9 (poison-medicinal agt NOS) and E962.0 (assault-pois w medic agt). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
