T36.AX5A: Adverse effect of fluoroquinolone antibiotics, initial encounter

New code · FY2026

Billable: use this code on claims.

• New code, effective October 1, 2025 (FY2026).

Code breakdown

Coding notes

Excludes1 (from T36)

• antineoplastic antibiotics (T45.1-)
• locally applied antibiotic NEC (T49.0)
• topically used antibiotic for ear, nose and throat (T49.6)
• topically used antibiotic for eye (T49.5)

7th character (from T36)

• The appropriate 7th character is to be added to each code from category T36

7th characters (category T36)

• A initial encounter
• D subsequent encounter
• S sequela

Medicare coverage

T36.AX5A is listed as a covered diagnosis in 5 Medicare billing and coding articles:

• A56538 Billing and Coding: Allergen Immunotherapy
• A56558 Billing and Coding: Allergy Testing
• A57361 Billing and Coding: Monitored Anesthesia Care
• A57531 Billing and Coding: Allergy Testing
• A57678 Billing and Coding: Allergen Immunotherapy

Check this code

• Code search: full entry and nearby codes
• Excludes checker: can it be billed with another code?
• Coverage checker: is it covered for your CPT code?

All FY2026 ICD-10-CM changes

ICD-10-CM codes and descriptions are from the CMS and NCHS code files. Coverage is from the CMS Medicare Coverage Database billing and coding articles.