Z03.6 Encounter for observation for suspected toxic effect from ingested substance ruled out

The ICD-10-CM code for Encounter for observation for suspected toxic effect from ingested substance ruled out is Z03.6 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

21: Factors influencing health status and contact with health services (Z00-Z99)

Section

Z00-Z13: Persons encountering health services for examinations (Z00-Z13)

Category Z03

19 codes (14 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to Z03.6:

• Observation (following) (for) (without need for further medical care) › adverse effect of drug
• Observation (following) (for) (without need for further medical care) › toxic effects from ingested substance (drug) (poison)
• Self-poisoning › observation following (alleged) attempt
• Observation (following) (for) (without need for further medical care) › suspected, ruled out › toxic effects from ingested substance (drug) (poison)
• Observation (following) (for) (without need for further medical care) › suicide attempt, alleged NEC › self-poisoning
• Observation (following) (for) (without need for further medical care) › suspected, ruled out › drug poisoning or adverse effect
• Observation (following) (for) (without need for further medical care) › suspected, ruled out › suicide attempt, alleged › self-poisoning

Inclusion Terms

• Encounter for observation for suspected adverse effect from drug
• Encounter for observation for suspected poisoning

U.S. Hospital Utilization

• An estimated 230 U.S. inpatient stays in 2023 included Z03.6 among the documented diagnoses.
• 80 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Used with any code in range A00.0-T88.9, Z00-Z99

1) Used with any code in the range of A00.0-T88.9, Z00-Z99 An external cause code may be used with any code in the range of A00.0-T88.9, Z00-Z99, classification that represents a health condition due to an external cause. Though they are most applicable to injuries, they are also valid for use with such things as infections or diseases due to an external source, and other health conditions, such as a heart attack that occurs during strenuous physical activity.

Additional codes with observation code (fragment)

observation code, but only if they are unrelated to the suspected condition being observed.

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)