ICD-10-CM Tabular Index · Chapter 19 · FY 2026 T36–T50
Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances (T36-T50) ICD-10-CM
The T36–T50 section covers poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances with 4,574 ICD-10-CM diagnosis codes, of which 3,186 are billable in fiscal year 2026. The section is organized into the 15 code ranges listed below.
✓ Built from the official CMS FY 2026 datasetEffective Oct 1, 2025 – Sep 30, 2026
15
Code Ranges
4,574
Diagnosis Codes
3,186
Billable Codes
T36–T50
Code Range
Includes
This note appears immediately under a three character code title to further define, or give examples of, the content of the category.
adverse effect of correct substance properly administered
poisoning by overdose of substance
poisoning by wrong substance given or taken in error
underdosing by (inadvertently) (deliberately) taking less substance than prescribed or instructed
Code First
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
, for adverse effects, the nature of the adverse effect, such as:
The “use additional code” indicates that a secondary code could be used to further specify the patient’s condition. This note is not mandatory and is only used if enough information is available to assign an additional code.
code(s) to specify:
manifestations of poisoning
underdosing or failure in dosage during medical and surgical care Y63.6Y63.8Y63.9
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
toxic reaction to local anesthesia in pregnancy O29.3
Type 2 Excludes
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
abuse and dependence of psychoactive substances F10F19
The info icon previews the code ranges inside each row and its instructional notations from the official Tabular List.
About the T36–T50 Code Range
ICD-10 codes T36 through T50 are used to specify cases of poisoning, adverse effects, and underdosing of various drugs, medicaments, and biological substances. These codes cover a wide range of substances including systemic antibiotics, anti-infectives, hormones, analgesics, narcotics, anesthetics, and vaccines, among others.
This comprehensive range helps identify and code specific situations such as accidental poisoning, intentional self-harm, assault, undetermined causes, adverse reactions, and underdosing. For instance, T36.0X1 relates to poisoning by penicillins and includes common synonyms like "penicillin overdose" or "poisoning by ampicillin," aiding in accurate coding. Similarly, T40.1X1 deals with accidental heroin poisoning, while T46.0X1 codes for accidental digoxin poisoning, the latter also known by terms like "digitalis toxicity". Adverse effects related to chemical reactions or allergic responses, such as "aspirin-induced asthma" under T39.015, are also represented. Underdosing codes capture instances where a patient receives less than the prescribed amount of a drug, which can be critical for treatment monitoring.
Medical coders and healthcare providers use these specific codes to capture detailed circumstances of drug-related poisonings and reactions, which include various drug classes like systemic antibiotics (penicillins, cephalosporins), hormones (glucocorticoids, thyroid hormones), analgesics (nonopioid and opioid), psychotropic drugs (antidepressants, antipsychotics), cardiovascular agents, gastrointestinal agents, and vaccines (like pertussis or smallpox vaccines). Keywords integrated naturally include "poisoning by penicillins," "adverse effect of anticoagulants," "intentional self-harm with antidepressants," and "underdosing of vaccines," facilitating precise classification and aiding in preventive care and research.
Questions About This Page
How many codes are in the T36-T50 range?
The T36-T50 range contains 4,574 ICD-10-CM diagnosis codes in FY 2026. 3,186 of them are billable, and the rest are category headers that organize the section.
What conditions does T36-T50 cover?
The range covers poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances. The code ranges listed above break it into groups of related conditions, and each one links to its own page with the full code list.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T36
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
anti-infectives topically used for ear, nose and throat T49.6
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T37
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T38
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T39
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
drug dependence and related mental and behavioral disorders due to psychoactive substance use F10F19
7th Character Note
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T40
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T41
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
drug dependence and related mental and behavioral disorders due to psychoactive substance use F10F19
7th Character Note
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T42
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
drug dependence and related mental and behavioral disorders due to psychoactive substance use F10F19
7th Character Note
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T43
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T44
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T45
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
poisoning by, adverse effect of and underdosing of metaraminol T44.4
7th Character Note
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T46
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T47
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T48
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
Poisoning by, adverse effect of and underdosing of topical agents primarily affecting skin and mucous membrane and by ophthalmological, otorhinorlaryngological and dental drugs (T49)
This note appears immediately under a three character code title to further define, or give examples of, the content of the category.
poisoning by, adverse effect of and underdosing of glucocorticoids, topically used
7th Character Note
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T49
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
The appropriate 7th character is to be added to each code from category T50
7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
