MCMCB Pro
T44.905A

T44.905AAdverse effect of unspecified drugs primarily affecting the autonomic nervous system, initial encounter

Billable / specific codeICD-10-CM

T44.905A is a billable, specific ICD-10-CM code for adverse effect of unspecified drugs primarily affecting the autonomic nervous system, initial encounter. It is valid for submission on a claim.

7th character "A" — initial encounter

The appropriate 7th character is to be added to each code from category T44

A
initial encounter
D
subsequent encounter
S
sequela

Risk adjustment

T44.905A does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Medicare coverage

T44.905A is named in 6 Medicare coverage policies 6 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

  • A56612Billing and Coding: CT of the Head
  • A56844Billing and Coding: RAST Type Tests
  • A57361Billing and Coding: Monitored Anesthesia Care
  • A57473Billing and Coding: Allergy Testing

Related codes at this level

Codes that share T44.905. If T44.905A is not quite right, the correct code is usually one of these.

Questions about T44.905A

Is T44.905A a billable ICD-10-CM code?
Yes. T44.905A is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does T44.905A sit in the tabular list?
Injury, poisoning and certain other consequences of external causes (S00-T88), in the block Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (T36-T50).
ICD-10-CMFY2026-Apr· effective April 1, 2026

Loaded directly from the CMS/NCHS ICD-10-CM public-domain release — see data sources and our editorial policy. If this page disagrees with the CMS tabular list, this page is wrong. Reference information for professional coders; not medical or billing advice.