T42Not billable, use a more specific code below
Poisoning by, adverse effect of and underdosing of antiepileptic, sedative- hypnotic and antiparkinsonism drugs
In Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (T36-T50), chapter 19: Injury, Poisoning and Certain Other Consequences of External Causes
162 billable codes under T42: none are a CC or MCC; 9 map to HCC 155 (Major Depression, Moderate or Severe, without Psychosis).An HCC counts toward a Medicare Advantage patient's risk score.
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Instructional notes
Also applies, from Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (T36-T50)
These notes sit on T36-T50 and apply to every code under it, including T42.
Includes: conditions that are coded here
- adverse effect of correct substance properly administered
- poisoning by overdose of substance
- poisoning by wrong substance given or taken in error
- underdosing by (inadvertently) (deliberately) taking less substance than prescribed or instructed
Excludes1: not coded here, use a different code
- toxic reaction to local anesthesia in pregnancy (O29.3-)
Excludes2: not included here, code separately if applicable
Code first: code the underlying condition first, then this code
Use additional code: add a second code for this, listed after this one
- code(s) to specify:
- manifestations of poisoning
- underdosing or failure in dosage during medical and surgical care (Y63.6, Y63.8-Y63.9)
- underdosing of medication regimen (Z91.12-, Z91.13-)
Official coding guidelines
From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.
- Section I.C.19.e Adverse Effects, Poisoning, Underdosing and Toxic Effects (page 82), covers T42
For adverse effects, code the effect first, then T36-T50 with character 5. Sequence poisonings (unknown intent coded accidental) and toxic effects (T51-T65) first; underdosing (character 6) is never first-listed.
Other Chapter 19 topics:
- Application of 7th Characters in Chapter 19 (page 77)
- Coding of Injuries (page 78)
- Coding of Traumatic Fractures (page 79)
- Coding of Burns and Corrosions (page 80)
- Adult and child abuse, neglect and other maltreatment (page 85)
- Complications of care (page 85)
All codes under T42
T42 can't be used on a claim. Pick a billable code below; grey headings group them.
- T42.0Poisoning by, adverse effect of and underdosing of hydantoin derivatives
- T42.0XPoisoning by, adverse effect of and underdosing of hydantoin derivatives
- T42.0X1Poisoning by hydantoin derivatives, accidental (unintentional)
- T42.0X1APoisoning by hydantoin derivatives, accidental (unintentional), initial encounter
- T42.0X1DPoisoning by hydantoin derivatives, accidental (unintentional), subsequent encounter
- T42.0X1SPoisoning by hydantoin derivatives, accidental (unintentional), sequela
- T42.0X2Poisoning by hydantoin derivatives, intentional self-harm
- T42.0X2APoisoning by hydantoin derivatives, intentional self-harm, initial encounter
- T42.0X2DPoisoning by hydantoin derivatives, intentional self-harm, subsequent encounter
- T42.0X2SPoisoning by hydantoin derivatives, intentional self-harm, sequela
- T42.0X3Poisoning by hydantoin derivatives, assault
- T42.0X3APoisoning by hydantoin derivatives, assault, initial encounter
- T42.0X3DPoisoning by hydantoin derivatives, assault, subsequent encounter
- T42.0X3SPoisoning by hydantoin derivatives, assault, sequela
- T42.0X4Poisoning by hydantoin derivatives, undetermined
- T42.0X4APoisoning by hydantoin derivatives, undetermined, initial encounter
- T42.0X4DPoisoning by hydantoin derivatives, undetermined, subsequent encounter
- T42.0X4SPoisoning by hydantoin derivatives, undetermined, sequela
- T42.0X5Adverse effect of hydantoin derivatives
- T42.0X5AAdverse effect of hydantoin derivatives, initial encounter
- T42.0X5DAdverse effect of hydantoin derivatives, subsequent encounter
- T42.0X5SAdverse effect of hydantoin derivatives, sequela
- T42.0X6Underdosing of hydantoin derivatives
- T42.0X6AUnderdosing of hydantoin derivatives, initial encounter
- T42.0X6DUnderdosing of hydantoin derivatives, subsequent encounter
- T42.0X6SUnderdosing of hydantoin derivatives, sequela
- T42.1Poisoning by, adverse effect of and underdosing of iminostilbenes
- T42.1XPoisoning by, adverse effect of and underdosing of iminostilbenes
- T42.1X1Poisoning by iminostilbenes, accidental (unintentional)
- T42.1X1APoisoning by iminostilbenes, accidental (unintentional), initial encounter
- T42.1X1DPoisoning by iminostilbenes, accidental (unintentional), subsequent encounter
- T42.1X1SPoisoning by iminostilbenes, accidental (unintentional), sequela
- T42.1X2Poisoning by iminostilbenes, intentional self-harm
- T42.1X2APoisoning by iminostilbenes, intentional self-harm, initial encounter
- T42.1X2DPoisoning by iminostilbenes, intentional self-harm, subsequent encounter
- T42.1X2SPoisoning by iminostilbenes, intentional self-harm, sequela
- T42.1X3Poisoning by iminostilbenes, assault
- T42.1X3APoisoning by iminostilbenes, assault, initial encounter
- T42.1X3DPoisoning by iminostilbenes, assault, subsequent encounter
- T42.1X3SPoisoning by iminostilbenes, assault, sequela
- T42.1X4Poisoning by iminostilbenes, undetermined
- T42.1X4APoisoning by iminostilbenes, undetermined, initial encounter
- T42.1X4DPoisoning by iminostilbenes, undetermined, subsequent encounter
- T42.1X4SPoisoning by iminostilbenes, undetermined, sequela
- T42.1X5Adverse effect of iminostilbenes
- T42.1X5AAdverse effect of iminostilbenes, initial encounter
- T42.1X5DAdverse effect of iminostilbenes, subsequent encounter
- T42.1X5SAdverse effect of iminostilbenes, sequela
- T42.1X6Underdosing of iminostilbenes
- T42.1X6AUnderdosing of iminostilbenes, initial encounter
- T42.1X6DUnderdosing of iminostilbenes, subsequent encounter
- T42.1X6SUnderdosing of iminostilbenes, sequela
- T42.2Poisoning by, adverse effect of and underdosing of succinimides and oxazolidinediones
- T42.2XPoisoning by, adverse effect of and underdosing of succinimides and oxazolidinediones
- T42.2X1Poisoning by succinimides and oxazolidinediones, accidental (unintentional)
- T42.2X1APoisoning by succinimides and oxazolidinediones, accidental (unintentional), initial encounter
- T42.2X1DPoisoning by succinimides and oxazolidinediones, accidental (unintentional), subsequent encounter
- T42.2X1SPoisoning by succinimides and oxazolidinediones, accidental (unintentional), sequela
- T42.2X2Poisoning by succinimides and oxazolidinediones, intentional self-harm
- T42.2X2APoisoning by succinimides and oxazolidinediones, intentional self-harm, initial encounter
- T42.2X2DPoisoning by succinimides and oxazolidinediones, intentional self-harm, subsequent encounter
- T42.2X2SPoisoning by succinimides and oxazolidinediones, intentional self-harm, sequela
- T42.2X3Poisoning by succinimides and oxazolidinediones, assault
- T42.2X3APoisoning by succinimides and oxazolidinediones, assault, initial encounter
- T42.2X3DPoisoning by succinimides and oxazolidinediones, assault, subsequent encounter
- T42.2X3SPoisoning by succinimides and oxazolidinediones, assault, sequela
- T42.2X4Poisoning by succinimides and oxazolidinediones, undetermined
- T42.2X4APoisoning by succinimides and oxazolidinediones, undetermined, initial encounter
- T42.2X4DPoisoning by succinimides and oxazolidinediones, undetermined, subsequent encounter
- T42.2X4SPoisoning by succinimides and oxazolidinediones, undetermined, sequela
- T42.2X5Adverse effect of succinimides and oxazolidinediones
- T42.2X5AAdverse effect of succinimides and oxazolidinediones, initial encounter
- T42.2X5DAdverse effect of succinimides and oxazolidinediones, subsequent encounter
- T42.2X5SAdverse effect of succinimides and oxazolidinediones, sequela
- T42.2X6Underdosing of succinimides and oxazolidinediones
- T42.2X6AUnderdosing of succinimides and oxazolidinediones, initial encounter
- T42.2X6DUnderdosing of succinimides and oxazolidinediones, subsequent encounter
- T42.2X6SUnderdosing of succinimides and oxazolidinediones, sequela
- T42.3Poisoning by, adverse effect of and underdosing of barbiturates
- T42.3XPoisoning by, adverse effect of and underdosing of barbiturates
- T42.3X1Poisoning by barbiturates, accidental (unintentional)
- T42.3X1APoisoning by barbiturates, accidental (unintentional), initial encounter
- T42.3X1DPoisoning by barbiturates, accidental (unintentional), subsequent encounter
- T42.3X1SPoisoning by barbiturates, accidental (unintentional), sequela
- T42.3X2Poisoning by barbiturates, intentional self-harm
- T42.3X2APoisoning by barbiturates, intentional self-harm, initial encounter
- T42.3X2DPoisoning by barbiturates, intentional self-harm, subsequent encounter
- T42.3X2SPoisoning by barbiturates, intentional self-harm, sequela
- T42.3X3Poisoning by barbiturates, assault
- T42.3X3APoisoning by barbiturates, assault, initial encounter
- T42.3X3DPoisoning by barbiturates, assault, subsequent encounter
- T42.3X3SPoisoning by barbiturates, assault, sequela
- T42.3X4Poisoning by barbiturates, undetermined
- T42.3X4APoisoning by barbiturates, undetermined, initial encounter
- T42.3X4DPoisoning by barbiturates, undetermined, subsequent encounter
- T42.3X4SPoisoning by barbiturates, undetermined, sequela
- T42.3X5Adverse effect of barbiturates
- T42.3X5AAdverse effect of barbiturates, initial encounter
- T42.3X5DAdverse effect of barbiturates, subsequent encounter
- T42.3X5SAdverse effect of barbiturates, sequela
- T42.3X6Underdosing of barbiturates
- T42.3X6AUnderdosing of barbiturates, initial encounter
- T42.3X6DUnderdosing of barbiturates, subsequent encounter
- T42.3X6SUnderdosing of barbiturates, sequela
- T42.4Poisoning by, adverse effect of and underdosing of benzodiazepines
- T42.4XPoisoning by, adverse effect of and underdosing of benzodiazepines
- T42.4X1Poisoning by benzodiazepines, accidental (unintentional)
- T42.4X1APoisoning by benzodiazepines, accidental (unintentional), initial encounter
- T42.4X1DPoisoning by benzodiazepines, accidental (unintentional), subsequent encounter
- T42.4X1SPoisoning by benzodiazepines, accidental (unintentional), sequela
- T42.4X2Poisoning by benzodiazepines, intentional self-harm
- T42.4X2APoisoning by benzodiazepines, intentional self-harm, initial encounter
- T42.4X2DPoisoning by benzodiazepines, intentional self-harm, subsequent encounter
- T42.4X2SPoisoning by benzodiazepines, intentional self-harm, sequela
- T42.4X3Poisoning by benzodiazepines, assault
- T42.4X3APoisoning by benzodiazepines, assault, initial encounter
- T42.4X3DPoisoning by benzodiazepines, assault, subsequent encounter
- T42.4X3SPoisoning by benzodiazepines, assault, sequela
- T42.4X4Poisoning by benzodiazepines, undetermined
- T42.4X4APoisoning by benzodiazepines, undetermined, initial encounter
- T42.4X4DPoisoning by benzodiazepines, undetermined, subsequent encounter
- T42.4X4SPoisoning by benzodiazepines, undetermined, sequela
- T42.4X5Adverse effect of benzodiazepines
- T42.4X5AAdverse effect of benzodiazepines, initial encounter
- T42.4X5DAdverse effect of benzodiazepines, subsequent encounter
- T42.4X5SAdverse effect of benzodiazepines, sequela
- T42.4X6Underdosing of benzodiazepines
- T42.4X6AUnderdosing of benzodiazepines, initial encounter
- T42.4X6DUnderdosing of benzodiazepines, subsequent encounter
- T42.4X6SUnderdosing of benzodiazepines, sequela
- T42.5Poisoning by, adverse effect of and underdosing of mixed antiepileptics
- T42.5XPoisoning by, adverse effect of and underdosing of antiepileptics
- T42.5X1Poisoning by mixed antiepileptics, accidental (unintentional)
- T42.5X1APoisoning by mixed antiepileptics, accidental (unintentional), initial encounter
- T42.5X1DPoisoning by mixed antiepileptics, accidental (unintentional), subsequent encounter
- T42.5X1SPoisoning by mixed antiepileptics, accidental (unintentional), sequela
- T42.5X2Poisoning by mixed antiepileptics, intentional self-harm
- T42.5X2APoisoning by mixed antiepileptics, intentional self-harm, initial encounter
- T42.5X2DPoisoning by mixed antiepileptics, intentional self-harm, subsequent encounter
- T42.5X2SPoisoning by mixed antiepileptics, intentional self-harm, sequela
- T42.5X3Poisoning by mixed antiepileptics, assault
- T42.5X3APoisoning by mixed antiepileptics, assault, initial encounter
- T42.5X3DPoisoning by mixed antiepileptics, assault, subsequent encounter
- T42.5X3SPoisoning by mixed antiepileptics, assault, sequela
- T42.5X4Poisoning by mixed antiepileptics, undetermined
- T42.5X4APoisoning by mixed antiepileptics, undetermined, initial encounter
- T42.5X4DPoisoning by mixed antiepileptics, undetermined, subsequent encounter
- T42.5X4SPoisoning by mixed antiepileptics, undetermined, sequela
- T42.5X5Adverse effect of mixed antiepileptics
- T42.5X5AAdverse effect of mixed antiepileptics, initial encounter
- T42.5X5DAdverse effect of mixed antiepileptics, subsequent encounter
- T42.5X5SAdverse effect of mixed antiepileptics, sequela
- T42.5X6Underdosing of mixed antiepileptics
- T42.5X6AUnderdosing of mixed antiepileptics, initial encounter
- T42.5X6DUnderdosing of mixed antiepileptics, subsequent encounter
- T42.5X6SUnderdosing of mixed antiepileptics, sequela
- T42.6Poisoning by, adverse effect of and underdosing of other antiepileptic and sedative-hypnotic drugs
- T42.6XPoisoning by, adverse effect of and underdosing of other antiepileptic and sedative-hypnotic drugs
- T42.6X1Poisoning by other antiepileptic and sedative-hypnotic drugs, accidental (unintentional)
- T42.6X1APoisoning by other antiepileptic and sedative-hypnotic drugs, accidental (unintentional), initial encounter
- T42.6X1DPoisoning by other antiepileptic and sedative-hypnotic drugs, accidental (unintentional), subsequent encounter
- T42.6X1SPoisoning by other antiepileptic and sedative-hypnotic drugs, accidental (unintentional), sequela
- T42.6X2Poisoning by other antiepileptic and sedative-hypnotic drugs, intentional self-harm
- T42.6X2APoisoning by other antiepileptic and sedative-hypnotic drugs, intentional self-harm, initial encounter
- T42.6X2DPoisoning by other antiepileptic and sedative-hypnotic drugs, intentional self-harm, subsequent encounter
- T42.6X2SPoisoning by other antiepileptic and sedative-hypnotic drugs, intentional self-harm, sequela
- T42.6X3Poisoning by other antiepileptic and sedative-hypnotic drugs, assault
- T42.6X3APoisoning by other antiepileptic and sedative-hypnotic drugs, assault, initial encounter
- T42.6X3DPoisoning by other antiepileptic and sedative-hypnotic drugs, assault, subsequent encounter
- T42.6X3SPoisoning by other antiepileptic and sedative-hypnotic drugs, assault, sequela
- T42.6X4Poisoning by other antiepileptic and sedative-hypnotic drugs, undetermined
- T42.6X4APoisoning by other antiepileptic and sedative-hypnotic drugs, undetermined, initial encounter
- T42.6X4DPoisoning by other antiepileptic and sedative-hypnotic drugs, undetermined, subsequent encounter
- T42.6X4SPoisoning by other antiepileptic and sedative-hypnotic drugs, undetermined, sequela
- T42.6X5Adverse effect of other antiepileptic and sedative-hypnotic drugs
- T42.6X5AAdverse effect of other antiepileptic and sedative-hypnotic drugs, initial encounter
- T42.6X5DAdverse effect of other antiepileptic and sedative-hypnotic drugs, subsequent encounter
- T42.6X5SAdverse effect of other antiepileptic and sedative-hypnotic drugs, sequela
- T42.6X6Underdosing of other antiepileptic and sedative-hypnotic drugs
- T42.6X6AUnderdosing of other antiepileptic and sedative-hypnotic drugs, initial encounter
- T42.6X6DUnderdosing of other antiepileptic and sedative-hypnotic drugs, subsequent encounter
- T42.6X6SUnderdosing of other antiepileptic and sedative-hypnotic drugs, sequela
- T42.7Poisoning by, adverse effect of and underdosing of unspecified antiepileptic and sedative-hypnotic drugs
- T42.71Poisoning by unspecified antiepileptic and sedative-hypnotic drugs, accidental (unintentional)
- T42.71XAPoisoning by unspecified antiepileptic and sedative-hypnotic drugs, accidental (unintentional), initial encounter
- T42.71XDPoisoning by unspecified antiepileptic and sedative-hypnotic drugs, accidental (unintentional), subsequent encounter
- T42.71XSPoisoning by unspecified antiepileptic and sedative-hypnotic drugs, accidental (unintentional), sequela
- T42.72Poisoning by unspecified antiepileptic and sedative-hypnotic drugs, intentional self-harm
- T42.72XAPoisoning by unspecified antiepileptic and sedative-hypnotic drugs, intentional self-harm, initial encounter
- T42.72XDPoisoning by unspecified antiepileptic and sedative-hypnotic drugs, intentional self-harm, subsequent encounter
- T42.72XSPoisoning by unspecified antiepileptic and sedative-hypnotic drugs, intentional self-harm, sequela
- T42.73Poisoning by unspecified antiepileptic and sedative-hypnotic drugs, assault
- T42.73XAPoisoning by unspecified antiepileptic and sedative-hypnotic drugs, assault, initial encounter
- T42.73XDPoisoning by unspecified antiepileptic and sedative-hypnotic drugs, assault, subsequent encounter
- T42.73XSPoisoning by unspecified antiepileptic and sedative-hypnotic drugs, assault, sequela
- T42.74Poisoning by unspecified antiepileptic and sedative-hypnotic drugs, undetermined
- T42.74XAPoisoning by unspecified antiepileptic and sedative-hypnotic drugs, undetermined, initial encounter
- T42.74XDPoisoning by unspecified antiepileptic and sedative-hypnotic drugs, undetermined, subsequent encounter
- T42.74XSPoisoning by unspecified antiepileptic and sedative-hypnotic drugs, undetermined, sequela
- T42.75Adverse effect of unspecified antiepileptic and sedative-hypnotic drugs
- T42.75XAAdverse effect of unspecified antiepileptic and sedative-hypnotic drugs, initial encounter
- T42.75XDAdverse effect of unspecified antiepileptic and sedative-hypnotic drugs, subsequent encounter
- T42.75XSAdverse effect of unspecified antiepileptic and sedative-hypnotic drugs, sequela
- T42.76Underdosing of unspecified antiepileptic and sedative-hypnotic drugs
- T42.76XAUnderdosing of unspecified antiepileptic and sedative-hypnotic drugs, initial encounter
- T42.76XDUnderdosing of unspecified antiepileptic and sedative-hypnotic drugs, subsequent encounter
- T42.76XSUnderdosing of unspecified antiepileptic and sedative-hypnotic drugs, sequela
- T42.8Poisoning by, adverse effect of and underdosing of antiparkinsonism drugs and other central muscle-tone depressants
- T42.8XPoisoning by, adverse effect of and underdosing of antiparkinsonism drugs and other central muscle-tone depressants
- T42.8X1Poisoning by antiparkinsonism drugs and other central muscle-tone depressants, accidental (unintentional)
- T42.8X1APoisoning by antiparkinsonism drugs and other central muscle-tone depressants, accidental (unintentional), initial encounter
- T42.8X1DPoisoning by antiparkinsonism drugs and other central muscle-tone depressants, accidental (unintentional), subsequent encounter
- T42.8X1SPoisoning by antiparkinsonism drugs and other central muscle-tone depressants, accidental (unintentional), sequela
- T42.8X2Poisoning by antiparkinsonism drugs and other central muscle-tone depressants, intentional self-harm
- T42.8X2APoisoning by antiparkinsonism drugs and other central muscle-tone depressants, intentional self-harm, initial encounter
- T42.8X2DPoisoning by antiparkinsonism drugs and other central muscle-tone depressants, intentional self-harm, subsequent encounter
- T42.8X2SPoisoning by antiparkinsonism drugs and other central muscle-tone depressants, intentional self-harm, sequela
- T42.8X3Poisoning by antiparkinsonism drugs and other central muscle-tone depressants, assault
- T42.8X3APoisoning by antiparkinsonism drugs and other central muscle-tone depressants, assault, initial encounter
- T42.8X3DPoisoning by antiparkinsonism drugs and other central muscle-tone depressants, assault, subsequent encounter
- T42.8X3SPoisoning by antiparkinsonism drugs and other central muscle-tone depressants, assault, sequela
- T42.8X4Poisoning by antiparkinsonism drugs and other central muscle-tone depressants, undetermined
- T42.8X4APoisoning by antiparkinsonism drugs and other central muscle-tone depressants, undetermined, initial encounter
- T42.8X4DPoisoning by antiparkinsonism drugs and other central muscle-tone depressants, undetermined, subsequent encounter
- T42.8X4SPoisoning by antiparkinsonism drugs and other central muscle-tone depressants, undetermined, sequela
- T42.8X5Adverse effect of antiparkinsonism drugs and other central muscle-tone depressants
- T42.8X5AAdverse effect of antiparkinsonism drugs and other central muscle-tone depressants, initial encounter
- T42.8X5DAdverse effect of antiparkinsonism drugs and other central muscle-tone depressants, subsequent encounter
- T42.8X5SAdverse effect of antiparkinsonism drugs and other central muscle-tone depressants, sequela
- T42.8X6Underdosing of antiparkinsonism drugs and other central muscle-tone depressants
- T42.8X6AUnderdosing of antiparkinsonism drugs and other central muscle-tone depressants, initial encounter
- T42.8X6DUnderdosing of antiparkinsonism drugs and other central muscle-tone depressants, subsequent encounter
- T42.8X6SUnderdosing of antiparkinsonism drugs and other central muscle-tone depressants, sequela
T42 MS-DRGs
As the principal diagnosis, the billable codes under T42 group to these 9 MS-DRGs (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.
- DRG 949 Aftercare with CC/MCC (63 of 162 codes)
- DRG 950 Aftercare without CC/MCC (63 of 162 codes)
- DRG 917 Poisoning and Toxic Effects of Drugs with MCC (45 of 162 codes)
- DRG 918 Poisoning and Toxic Effects of Drugs without MCC (45 of 162 codes)
- DRG 922 Other Injury, Poisoning and Toxic Effect Diagnoses with MCC (45 of 162 codes)
- DRG 923 Other Injury, Poisoning and Toxic Effect Diagnoses without MCC (45 of 162 codes)
- DRG 791 Prematurity with Major Problems (9 of 162 codes)
- DRG 793 Full Term Neonate with Major Problems (9 of 162 codes)
- DRG 951 Other Factors Influencing Health Status (9 of 162 codes)
Other codes that refer to T42
Notes on these codes point to T42.
- F13.2 Excludes2: sedative, hypnotic, or anxiolytic poisoning (T42.-)
About the condition
Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.
Drug Reactions
Most of the time, medicines make our lives better. They reduce aches and pains, fight infections, and control problems such as high blood pressure or diabetes. But medicines can also cause unwanted reactions, such as drug interactions, side effects, and allergies.
Read more about drug reactions on MedlinePlusCode history
Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.