T44.991APoisoning by other drug primarily affecting the autonomic nervous system, accidental (unintentional), initial encounter

T44.991A is the ICD-10-CM diagnosis code for poisoning by other drug primarily affecting the autonomic nervous system, accidental (unintentional), initial encounter. It belongs to category T44 (poisoning by, adverse effect of and underdosing of drugs primarily affecting the autonomic nervous system), block T36-T50 (poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

The 7th character "A" means initial encounter: use it while the patient is receiving active treatment for the condition.

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 917 (Poisoning and Toxic Effects of Drugs with MCC, relative weight 1.57) and DRG 918 (Poisoning and Toxic Effects of Drugs without MCC, relative weight 0.872), in MDC 21 (Injuries, Poisonings and Toxic Effects of Drugs), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 971.9 (poisoning by unspecified drug primarily affecting autonomic nervous system) and E855.8 (accidental poisoning by other specified drugs acting on central and autonomic nervous systems).