2026 ICD-10-CM Diagnosis Code T50.5X6AUnderdosing of appetite depressants, initial encounter
T50.5X6A is a billable ICD-10-CM diagnosis code for underdosing of appetite depressants, 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 T50.5X6A.
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 diuretics and other and unspecified drugs, medicaments and biological substances (T50). 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
Aminorex
an amphetamine-like anorectic agent. it may cause pulmonary hypertension.Benzphetamine
a sympathomimetic agent with properties similar to dextroamphetamine. it is used in the treatment of obesity. (from martindale, the extra pharmacopoeia, 30th ed, p1222)Chlorphentermine
a sympathomimetic agent that was formerly used as an anorectic. it has properties similar to those of dextroamphetamine. it has been implicated in lipid storage disorders and pulmonary hypertension. (from martindale, the extra pharmacopoeia, 30th ed, p1223)Dexfenfluramine
the s-isomer of fenfluramine. it is a serotonin agonist and is used as an anorectic. unlike fenfluramine, it does not possess any catecholamine agonist activity.Diethylpropion
a appetite depressant considered to produce less central nervous system disturbance than most drugs in this therapeutic category. it is also considered to be among the safest for patients with hypertension. (from ama drug evaluations annual, 1994, p2290)Fenfluramine
a centrally active drug that apparently both blocks serotonin uptake and provokes transport-mediated serotonin release.Mazindol
tricyclic anorexigenic agent unrelated to and less toxic than amphetamine, but with some similar side effects. it inhibits uptake of catecholamines and blocks the binding of cocaine to the dopamine uptake transporter.Phenmetrazine
a sympathomimetic drug used primarily as an appetite depressant. its actions and mechanisms are similar to dextroamphetamine.Phentermine
a central nervous system stimulant and sympathomimetic with actions and uses similar to those of dextroamphetamine. it has been used most frequently in the treatment of obesity.
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 T50.5X6A to ICD-9-CMHistory
Code HistoryHistory
Questions About T50.5X6AOverview
Is T50.5X6A (Underdosing of appetite depressants) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report underdosing of appetite depressants, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T50.5X6A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for underdosing of appetite depressants, such as an emergency visit or first evaluation.
Can T50.5X6A be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because underdosing of appetite depressants, 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.
