2026 ICD-10-CM Diagnosis Code T43.225AAdverse effect of selective serotonin reuptake inhibitors, initial encounter
T43.225A is a billable ICD-10-CM diagnosis code for adverse effect of selective serotonin 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) and groups to MS-DRG 917 through 918. The code is not accepted as a principal diagnosis by the Medicare Code Editor. Coders also document this condition as citalopram adverse reaction. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Adverse effects of drugs and medicaments, initial encounter.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for T43.225A.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Citalopram adverse reaction
- Fluoxetine adverse reaction
- Fluvoxamine adverse reaction
- Nefazodone adverse reaction
- Paroxetine adverse reaction
- Post selective serotonin re-uptake inhibitor sexual dysfunction
- Selective serotonin re-uptake inhibitor adverse reaction
- Sertraline adverse reaction
- Sexual dysfunction caused by drug
- Sexual dysfunction caused by psychoactive substance
Coding GuidelinesGuidance
When coding an adverse effect of a drug that has been correctly prescribed and properly administered, assign the appropriate code for the nature of the adverse effect followed by the appropriate code for the adverse effect of the drug.
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
Citalopram
a furancarbonitrile that is one of the selective serotonin reuptake inhibitors used as an antidepressant. the drug is also effective in reducing ethanol uptake in alcoholics and is used in depressed patients who also suffer from tardive dyskinesia in preference to tricyclic antidepressants, which aggravate dyskinesia.Fluoxetine
the first highly specific serotonin uptake inhibitor. it is used as an antidepressant and often has a more acceptable side-effects profile than traditional antidepressants.Fluvoxamine
a selective serotonin reuptake inhibitor that is used in the treatment of depression and a variety of anxiety disorders.Zimeldine
one of the selective serotonin reuptake inhibitors formerly used for depression but was withdrawn worldwide in september 1983 because of the risk of guillain-barre syndrome associated with its use. (from martindale, the extra pharmacopoeia, 29th ed, p385)
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.
| Substance | Accidental | Self-harm | Assault | Undetermined | Adverse Effect | Underdosing |
|---|---|---|---|---|---|---|
| Citalopram | T43.221 | T43.222 | T43.223 | T43.224 | T43.225 | T43.226 |
| Femoxetine | T43.221 | T43.222 | T43.223 | T43.224 | T43.225 | T43.226 |
| Fluoxetine | T43.221 | T43.222 | T43.223 | T43.224 | T43.225 | T43.226 |
| Fluvoxamine | T43.221 | T43.222 | T43.223 | T43.224 | T43.225 | T43.226 |
| Indalpine | T43.221 | T43.222 | T43.223 | T43.224 | T43.225 | T43.226 |
| Zimeldine | T43.221 | T43.222 | T43.223 | T43.224 | T43.225 | T43.226 |
Patient EducationClinical
Drug Reactions
Most of the time, medicines make our lives better. They reduce aches and pains, fight infections, and control problems such as high blood pressure or diabetes. But medicines can also cause unwanted reactions, such as drug interactions, side effects, and allergies.
The full article covers:
- What is a drug interaction?
- What are side effects?
- What are drug allergies?
- How can I stay safe when taking medicines?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T43.225A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T43.225AOverview
Is T43.225A (Adverse effect of selective serotonin reuptake inhibitors) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report adverse effect of selective serotonin reuptake inhibitors, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T43.225A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for adverse effect of selective serotonin reuptake inhibitors, such as an emergency visit or first evaluation.
What MS-DRG does T43.225A group to?
On inpatient claims, adverse effect of selective serotonin reuptake inhibitors, initial encounter maps to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.
Can T43.225A be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because adverse effect of selective serotonin reuptake inhibitors, initial encounter describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.
What is the ICD-9 equivalent of T43.225A?
Under the General Equivalence Mappings, adverse effect of selective serotonin reuptake inhibitors, initial encounter converts to ICD-9-CM 995.29 (adv eff med/biol NEC/NOS) and E939.0 (adv eff antidepressants). The mapping is approximate, so confirm the match fits the documentation.
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.
