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  6. 2026 ICD-10-CM Code T36.AX6

2026 ICD-10-CM Diagnosis Code T36.AX6

Underdosing of fluoroquinolone antibiotics

ICD-10-CM Code:
T36.AX6
ICD-10 Code for:
Underdosing of fluoroquinolone antibiotics
Is Billable?
Not Valid for Submission
Code Navigator:

T36.AX6 is a non-specific and non-billable diagnosis code code, consider using a code with a higher level of specificity for a diagnosis of underdosing of fluoroquinolone antibiotics. The code is not specific and is NOT valid for the year 2026 for the submission of HIPAA-covered transactions. Category or Header define the heading of a category of codes that may be further subdivided by the use of 4th, 5th, 6th or 7th characters.

Specific Coding Applicable to Underdosing of fluoroquinolone antibiotics

Non-specific codes like T36.AX6 require more digits to indicate the appropriate level of specificity. Consider using any of the following ICD-10-CM codes with a higher level of specificity when coding for underdosing of fluoroquinolone antibiotics:

  • Use T36.AX6A for initial encounter - BILLABLE CODE

  • Use T36.AX6D for subsequent encounter - BILLABLE CODE

  • Use T36.AX6S for sequela - BILLABLE CODE

Code Classification

  • Injury, poisoning and certain other consequences of external causes
    S00–T88
    • Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances
      T36-T50
      • Poisoning by, adverse effect of and underdosing of systemic antibiotics
        T36

Coding Guidelines

Underdosing refers to taking less of a medication than is prescribed by a provider or a manufacturer's instruction. Codes for underdosing should never be assigned as principal or first-listed codes. If a patient has a relapse or exacerbation of the medical condition for which the drug is prescribed because of the reduction in dose, then the medical condition itself should be coded.

The appropriate 7th character is to be added to each code from block Poisoning by, adverse effect of and underdosing of systemic antibiotics (T36). Use the following options for the aplicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Table of Drugs and Chemicals

The code is referenced in the Table of Drugs and Chemicals, this table contains a classification of drugs, industrial solvents, corrosive gases, noxious plants, pesticides, and other toxic agents.

According to ICD-10-CM coding guidelines it is advised to do not code directly from the Table of Drugs and Chemicals, instead always refer back to the Tabular List when doing the initial coding. Each substance in the table is assigned a code according to the poisoning classification and external causes of adverse effects. It is important to use as many codes as necessary to specify all reported drugs, medicinal or chemical substances. If the same diagnosis code describes the causative agent for more than one adverse reaction, poisoning, toxic effect or underdosing, utilize the code only once.

Substance Poisoning
Accidental
(unintentional)		 Poisoning
Accidental
(self-harm)		 Poisoning
Assault		 Poisoning
Undetermined		 Adverse
effect		 Underdosing
Fluoroquinolone antibioticsT36.AX1T36.AX2T36.AX3T36.AX4T36.AX5T36.AX6

Code History

  • FY 2026 - No Change, effective from 10/1/2025 through 9/30/2026