2026 ICD-10-CM Diagnosis Code T36.AX4SPoisoning by fluoroquinolone antibiotics, undetermined, sequela
T36.AX4S is a billable ICD-10-CM diagnosis code for poisoning by fluoroquinolone antibiotics, undetermined, sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 922 through 923. The code is exempt from POA reporting.
Code Identity
Code Classification
Present on Admission (POA)Billing
T36.AX4S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.
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 systemic antibiotics (T36). 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.
Table of Drugs and ChemicalsClinical
Code History & ChangesHistory
New Code T36.AX4S was added to the ICD-10-CM code set for FY 2026, effective October 1, 2025.
Replacement T36.AX4S replaces the following previously assigned code(s):
- T36.8X4S - Poisoning by oth systemic antibiotics, undetermined, sequela
Questions About T36.AX4SOverview
Is T36.AX4S (Poisoning by fluoroquinolone antibiotics, undetermined) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report poisoning by fluoroquinolone antibiotics, undetermined, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character S in T36.AX4S mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the poisoning by fluoroquinolone antibiotics, undetermined itself has resolved, not the original event.
What MS-DRG does T36.AX4S group to?
When poisoning by fluoroquinolone antibiotics, undetermined, sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 922, 923, with relative weights from 1.0177 to 1.7494 depending on complications. Higher weights mean higher Medicare reimbursement.
Is T36.AX4S exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for poisoning by fluoroquinolone antibiotics, undetermined, sequela on inpatient claims.
