T44
Non-Billable (Header)Poisoning by, adverse effect of and underdosing of drugs primarily affecting the autonomic nervous system
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
What This Code Means
T44 is the ICD-10-CM diagnosis code for poisoning by, adverse effect of and underdosing of drugs primarily affecting the autonomic nervous system. T44 sits in the ICD-10-CM chapter for injury, poisoning and certain other consequences of external causes (s00-t88), within the section covering poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (t36-t50).
Header codes like T44 cannot be reported on claims directly — they organize child codes that share clinical context but the actual diagnosis must be coded to the highest level of specificity supported by the documentation. Coders should look at T44's child codes and select the one that matches the patient's documented presentation, since payers reject header codes submitted as the primary diagnosis. For risk adjustment workflows, header codes never contribute to a Medicare Advantage member's RAF score on their own; only billable child codes that happen to map to a payment HCC affect risk-adjusted plan payments.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for T44 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.