2026 ICD-10-CM Diagnosis Code T43.216AUnderdosing of selective serotonin and norepinephrine reuptake inhibitors, initial encounter
T43.216A is a billable ICD-10-CM diagnosis code for underdosing of selective serotonin and norepinephrine reuptake inhibitors, 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 T43.216A.
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 psychotropic drugs, not elsewhere classified (T43). 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
Trazodone
a serotonin uptake inhibitor that is used as an antidepressive agent. it has been shown to be effective in patients with major depressive disorders and other subsets of depressive disorders. it is generally more useful in depressive disorders associated with insomnia and anxiety. this drug does not aggravate psychotic symptoms in patients with schizophrenia or schizoaffective disorders. (from ama drug evaluations annual, 1994, p309)
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
Antidepressants
Antidepressants are prescription medicines to treat depression. Depression is more than feeling a little sad or "blue" for a few days. It's a very common, serious medical illness that affects your mood and general mental health It can make you feel tired, hopeless, worried, or fearful. It can change your thinking, sleeping, and eating.
The full article covers:
- What are antidepressants?
- Are antidepressants used for other conditions?
- What are the different types of antidepressants?
- Which type of antidepressant is right for me?
- How long do antidepressants take to work?
- How long will I need to take an antidepressant?
- What are the side effects of antidepressants?
- What can I do to take antidepressants safely?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T43.216A to ICD-9-CMHistory
Code HistoryHistory
Questions About T43.216AOverview
Is T43.216A a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report underdosing of selective serotonin and norepinephrine reuptake inhibitors, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T43.216A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for underdosing of selective serotonin and norepinephrine reuptake inhibitors, such as an emergency visit or first evaluation.
Can T43.216A be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because underdosing of selective serotonin and norepinephrine reuptake inhibitors, 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.
