Fluoroquinolone Antibiotics

Today, “In the kNOW” will be looking at recent guidance and coding changes related to the use of fluoroquinolone antibiotics.

With the October 1st, 2025 ICD-10-CM coding updates, the Table of Drugs and Chemicals was updated with new codes to cover poisonings, adverse effects, and underdosing related to the use of fluoroquinolone antibiotics. These are a type of antibiotic used to treat bacterial infections and are considered broad-spectrum meaning they can be used to treat both gram-negative and gram-positive infections. Coding professionals may be more familiar with the brand-names of these antibiotics including Cipro, Levaquin, and Avelox to name a few.

Here are the new codes:

T36.AX1- Poisoning by fluoroquinolone antibiotics, accidental (unintentional)

     Poisoning by fluoroquinolone antibiotics NOS

T36.AX2- Poisoning by fluoroquinolone antibiotics, intentional self-harm
T36.AX3- Poisoning by fluoroquinolone antibiotics, assault
T36.AX4- Poisoning by fluoroquinolone antibiotics, undetermined
T36.AX5- Adverse effect of fluoroquinolone antibiotics
T36.AX6- Underdosing of fluoroquinolone antibiotics

Here is a brief coding scenario:
A woman was discharged from the hospital on Cipro for her cystitis. Her husband began to feel unwell and took some of her medication. Shortly after taking the Cipro, he developed tremors and experienced visual hallucinations. Which of the above listed codes should be assigned?

Because the husband took medication that was not intended for him, this event is considered a poisoning. Code T36.AX1A should be assigned. This code would be sequenced first followed by G25.1 (drug-induced tremor) and R44.1 (visual hallucinations).

If we take the same the scenario and now have the wife experience the visual hallucinations and tremors, the coding and sequencing changes. This would be an adverse effect, since the medication had been properly prescribed and taken. In this scenario, sequence either the visual hallucinations or the tremors first, followed by T36.AX5A for the adverse effect of the fluoroquinolone antibiotics. 

Now you are In the kNOW!!

 

About the Author

Dianna Foley, RHIA, CCS, CDIP, CHPS, has 25 years of HIM experience. She earned her bachelor’s degree from the University of Cincinnati and holds RHIA, CHPS, CDIP, and CCS certifications from AHIMA. Dianna’s an AHIMA-approved ICD-10-CM/PCS trainer, an AHIMA-published author, a participant in AHIMA credential item writing and exam development, and served on the AHIMA Nominating Committee. Dianna has held various HIM positions and is now an independent coding consultant. She previously served as a program director for Medical Coding and HIT. She presents on coding topics at the national, state, and regional levels and serves as OHIMA’s Education Coordinator.