2026 ICD-10-CM Diagnosis Code T36.7X6AUnderdosing of antifungal antibiotics, systemically used, initial encounter
T36.7X6A is a billable ICD-10-CM diagnosis code for underdosing of antifungal antibiotics, systemically used, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is not accepted as a principal diagnosis by the Medicare Code Editor. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Underdosing of drugs and medicaments, initial encounter.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for T36.7X6A.
Coding GuidelinesGuidance
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 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.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Amphotericin B
macrolide antifungal antibiotic produced by streptomyces nodosus obtained from soil of the orinoco river region of venezuela.Griseofulvin
an antifungal agent used in the treatment of tinea infections.Mepartricin
polyene macrolide antibiotic with unknown composition. it is obtained from streptomyces aureofaciens. it is used as an antifungal agent, an antiprotozoal agent, and in the treatment of benign prostatic hypertrophy.Nystatin
macrolide antifungal antibiotic complex produced by streptomyces noursei, s. aureus, and other streptomyces species. the biologically active components of the complex are nystatin a1, a2, and a3.
Table of Drugs and ChemicalsClinical
Substances in the Table of Drugs and Chemicals that reference this code family. Always confirm in the Tabular List before coding.
Patient EducationClinical
Antibiotics
Antibiotics are medicines that fight bacterial infections in people and animals. They work by killing the bacteria or by making it hard for the bacteria to grow and multiply.
The full article covers:
- What are antibiotics?
- What do antibiotics treat?
- Do antibiotics treat viral infections?
- What are the side effects of antibiotics?
- Why is it important to take antibiotics only when they're needed?
- How do I use antibiotics correctly?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T36.7X6A to ICD-9-CMHistory
Code HistoryHistory
Questions About T36.7X6AOverview
Is T36.7X6A (Underdosing of antifungal antibiotics, systemically used) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report underdosing of antifungal antibiotics, systemically used, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T36.7X6A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for underdosing of antifungal antibiotics, systemically used, such as an emergency visit or first evaluation.
Can T36.7X6A be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because underdosing of antifungal antibiotics, systemically used, initial encounter describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
