2026 ICD-10-CM Diagnosis Code T39.396AUnderdosing of other nonsteroidal anti-inflammatory drugs [NSAID], initial encounter
T39.396A is a billable ICD-10-CM diagnosis code for underdosing of other nonsteroidal anti-inflammatory drugs [NSAID], 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 T39.396A.
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.
Clinical InformationClinical
Diclofenac
a non-steroidal anti-inflammatory agent (nsaid) with antipyretic and analgesic actions. it is primarily available as the sodium salt.Etodolac
a non-steroidal anti-inflammatory agent and cyclooxygenase-2 (cox-2) inhibitor with potent analgesic and anti-arthritic properties. it has been shown to be effective in the treatment of osteoarthritis; rheumatoid arthritis; ankylosing spondylitis; and in the alleviation of postoperative pain (pain, postoperative).Flufenamic Acid
an anthranilic acid derivative with analgesic, anti-inflammatory, and antipyretic properties. it is used in musculoskeletal and joint disorders and administered by mouth and topically. (from martindale, the extra pharmacopoeia, 30th ed, p16)Indomethacin
a non-steroidal anti-inflammatory agent (nsaid) that inhibits cyclooxygenase, which is necessary for the formation of prostaglandins and other autacoids. it also inhibits the motility of polymorphonuclear leukocytes.Meclofenamic Acid
a non-steroidal anti-inflammatory agent with antipyretic and antigranulation activities. it also inhibits prostaglandin biosynthesis.Mefenamic Acid
a non-steroidal anti-inflammatory agent with analgesic, anti-inflammatory, and antipyretic properties. it is an inhibitor of cyclooxygenase.Nabumetone
a butanone non-steroidal anti-inflammatory drug and cyclooxygenase-2 (cox2) inhibitor that is used in the management of pain associated with osteoarthritis and rheumatoid arthritis.Piroxicam
a cyclooxygenase inhibiting, non-steroidal anti-inflammatory agent (nsaid) that is well established in treating rheumatoid arthritis and osteoarthritis and used for musculoskeletal disorders, dysmenorrhea, and postoperative pain. its long half-life enables it to be administered once daily.Sulindac
a sulfinylindene derivative prodrug whose sulfinyl moiety is converted in vivo to an active nsaid analgesic. specifically, the prodrug is converted by liver enzymes to a sulfide which is excreted in the bile and then reabsorbed from the intestine. this helps to maintain constant blood levels with reduced gastrointestinal side effects.Tolmetin
a non-steroidal anti-inflammatory agent (anti-inflammatory agents, non-steroidal) similar in mode of action to indomethacin.
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
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 T39.396A to ICD-9-CMHistory
Code HistoryHistory
Questions About T39.396AOverview
Is T39.396A a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report underdosing of other nonsteroidal anti-inflammatory drugs [NSAID], initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T39.396A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for underdosing of other nonsteroidal anti-inflammatory drugs [NSAID], such as an emergency visit or first evaluation.
Can T39.396A be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because underdosing of other nonsteroidal anti-inflammatory drugs [NSAID], 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.
