2026 ICD-10-CM Diagnosis Code T39.316AUnderdosing of propionic acid derivatives, initial encounter

ICD-10-CM Codes›S00–T88›T36-T50›T39

ICD-10-CM T39.316A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T39.316A is a billable ICD-10-CM diagnosis code for underdosing of propionic acid derivatives, 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

ICD-10-CM Code
T39.316A
Billable Status
Yes — Valid for Submission
Code Describes
Underdosing of propionic acid derivatives, initial encounter
Short Description
Underdosing of propionic acid derivatives, initial encounter
Same as the full description in the CMS dataset.
Parent Code
T39.316
Underdosing of propionic acid derivatives

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT36-T50Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances
CategoryT39Poisoning by, adverse effect of and underdosing of nonopioid analgesics, antipyretics and antirheumatics
This CodeT39.316AUnderdosing of propionic acid derivatives, initial encounter

Code EditsBilling

Medicare Code Editor checks that affect claim validity for T39.316A.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

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 nonopioid analgesics, antipyretics and antirheumatics (T39). 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.

CCSR INJ029
Underdosing of drugs and medicaments, initial encounter
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Fenoprofen

    a propionic acid derivative that is used as a non-steroidal anti-inflammatory agent.

  • Flurbiprofen

    an anti-inflammatory analgesic and antipyretic of the phenylalkynoic acid series. it has been shown to reduce bone resorption in periodontal disease by inhibiting carbonic anhydrase.

  • Ibuprofen

    a non-steroidal anti-inflammatory agent with analgesic, antipyretic, and anti-inflammatory properties

  • Ketoprofen

    an ibuprofen-type anti-inflammatory analgesic and antipyretic. it is used in the treatment of rheumatoid arthritis and osteoarthritis.

  • Carboxylesterase

    carboxylesterase is a serine-dependent esterase with wide substrate specificity. the enzyme is involved in the detoxification of xenobiotics and the activation of ester and of amide prodrugs.

  • Naproxen

    an anti-inflammatory agent with analgesic and antipyretic properties. both the acid and its sodium salt are used in the treatment of rheumatoid arthritis and other rheumatic or musculoskeletal disorders, dysmenorrhea, and acute gout.

  • Oxaprozin

    an oxazole-propionic acid derivative, cyclooxygenase inhibitor, and non-steroidal anti-inflammatory drug that is used in the treatment of pain and inflammation associated with of osteoarthritis; rheumatoid arthritis; and arthritis, juvenile.

  • Suprofen

    an ibuprofen-type anti-inflammatory analgesic and antipyretic. it inhibits prostaglandin synthesis and has been proposed as an anti-arthritic.

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.

SubstanceAccidentalSelf-harmAssaultUndeter­minedAdverse
Effect		Under­dosing
CarprofenT39.311T39.312T39.313T39.314T39.315T39.316
EsflurbiprofenT39.311T39.312T39.313T39.314T39.315T39.316
FenoprofenT39.311T39.312T39.313T39.314T39.315T39.316
FlurbiprofenT39.311T39.312T39.313T39.314T39.315T39.316
IbufenacT39.311T39.312T39.313T39.314T39.315T39.316
IbuprofenT39.311T39.312T39.313T39.314T39.315T39.316
IbuproxamT39.311T39.312T39.313T39.314T39.315T39.316
KetoprofenT39.311T39.312T39.313T39.314T39.315T39.316
NaproxenT39.311T39.312T39.313T39.314T39.315T39.316
OxaprozinT39.311T39.312T39.313T39.314T39.315T39.316
SuprofenT39.311T39.312T39.313T39.314T39.315T39.316
Tiaprofenic acidT39.311T39.312T39.313T39.314T39.315T39.316

Patient EducationClinical

Medication Errors

Medicines treat infectious diseases, prevent problems from chronic diseases, and ease pain. But medicines can also cause harmful reactions if not used correctly. Errors can happen in the hospital, at the health care provider's office, at the pharmacy, or at home. You can help prevent errors by:

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert T39.316A to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
No Map There is no ICD-9 equivalent for this code.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About T39.316AOverview

Is T39.316A (Underdosing of propionic acid derivatives) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report underdosing of propionic acid derivatives, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T39.316A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for underdosing of propionic acid derivatives, such as an emergency visit or first evaluation.

Can T39.316A be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because underdosing of propionic acid derivatives, 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.