2026 ICD-10-CM Diagnosis Code T43.594SPoisoning by other antipsychotics and neuroleptics, undetermined, sequela
T43.594S is a billable ICD-10-CM diagnosis code for poisoning by other antipsychotics and neuroleptics, undetermined, sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 922 through 923. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Poisoning/toxic effect/adverse effects/underdosing, sequela.
Code Identity
Code Classification
Present on Admission (POA)Billing
T43.594S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.
Coding GuidelinesGuidance
When coding a poisoning or reaction to the improper use of a medication (e.g., overdose, wrong substance given or taken in error, wrong route of administration), first assign the appropriate code from categories T36-T50. The poisoning codes have an associated intent as their 5th or 6th character (accidental, intentional self-harm, assault and undetermined). If the intent of the poisoning is unknown or unspecified, code the intent as accidental intent. The undetermined intent is only for use if the documentation in the record specifies that the intent cannot be determined. Use additional code(s) for all manifestations of poisonings.
The appropriate 7th character is to be added to each code from block Poisoning by, adverse effect of and underdosing of psychotropic drugs, not elsewhere classified (T43). Use the following options for the applicable episode of care:
- A - initial encounter
- D - subsequent encounter
- S - sequela
Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Amisulpride
a benzamide derivative that is used as an antipsychotic agent for the treatment of schizophrenia. it is also used as an antidepressive agent.Buspirone
an anxiolytic agent and serotonin receptor agonist belonging to the azaspirodecanedione class of compounds. its structure is unrelated to those of the benzodiazapines, but it has an efficacy comparable to diazepam.Droperidol
a butyrophenone with general properties similar to those of haloperidol. it is used in conjunction with an opioid analgesic such as fentanyl to maintain the patient in a calm state of neuroleptanalgesia with indifference to surroundings but still able to cooperate with the surgeon. it is also used as a premedicant, as an antiemetic, and for the control of agitation in acute psychoses. (from martindale, the extra pharmacopoeia, 29th ed, p593)Fluspirilene
a long-acting injectable antipsychotic agent used for chronic schizophrenia.Hydroxyzine
a histamine h1 receptor antagonist that is effective in the treatment of chronic urticaria, dermatitis, and histamine-mediated pruritus. unlike its major metabolite cetirizine, it does cause drowsiness. it is also effective as an antiemetic, for relief of anxiety and tension, and as a sedative.Loxapine
an antipsychotic agent used in schizophrenia.Meprobamate
a carbamate with hypnotic, sedative, and some muscle relaxant properties, although in therapeutic doses reduction of anxiety rather than a direct effect may be responsible for muscle relaxation. meprobamate has been reported to have anticonvulsant actions against petit mal seizures, but not against grand mal seizures (which may be exacerbated). it is used in the treatment of anxiety disorders, and also for the short-term management of insomnia but has largely been superseded by the benzodiazepines. (from martindale, the extra pharmacopoeia, 30th ed, p603)Molindone
an indole derivative effective in schizophrenia and other psychoses and possibly useful in the treatment of the aggressive type of undersocialized conduct disorder. molindone has much lower affinity for d2 receptors than most antipsychotic agents and has a relatively low affinity for d1 receptors. it has only low to moderate affinity for cholinergic and alpha-adrenergic receptors. some electrophysiologic data from animals indicate that molindone has certain characteristics that resemble those of clozapine. (from ama drug evaluations annual, 1994, p283)Olanzapine
a benzodiazepine derivative that binds serotonin receptors; muscarinic receptors; histamine h1 receptors; adrenergic alpha-1 receptors; and dopamine receptors. it is an antipsychotic agent used in the treatment of schizophrenia; bipolar disorder; and major depressive disorder; it may also reduce nausea and vomiting in patients undergoing chemotherapy.Penfluridol
one of the long-acting antipsychotic agents used for maintenance or long-term therapy of schizophrenia and other psychotic disorders.Pimozide
a diphenylbutylpiperidine that is effective as an antipsychotic agent and as an alternative to haloperidol for the suppression of vocal and motor tics in patients with tourette syndrome. although the precise mechanism of action is unknown, blockade of postsynaptic dopamine receptors has been postulated. (from ama drug evaluations annual, 1994, p403)Raclopride
a substituted benzamide that has antipsychotic properties. it is a dopamine d2 receptor (see receptors, dopamine d2) antagonist.Remoxipride
an antipsychotic agent that is specific for dopamine d2 receptors. it has been shown to be effective in the treatment of schizophrenia.Sulpiride
a dopamine d2-receptor antagonist. it has been used therapeutically as an antidepressant, antipsychotic, and as a digestive aid. (from merck index, 11th ed)Tetrabenazine
a drug formerly used as an antipsychotic and treatment of various movement disorders. tetrabenazine blocks neurotransmitter uptake into adrenergic storage vesicles and has been used as a high affinity label for the vesicle transport system.
Table of Drugs and ChemicalsClinical
Substances in the Table of Drugs and Chemicals that reference this code family. Always confirm in the Tabular List before coding.
Patient EducationClinical
Poisoning
A poison is any substance that is harmful to your body. You might swallow it, inhale it, inject it, or absorb it through your skin. Any substance can be poisonous if too much is taken. Poisons can include:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T43.594S to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T43.594SOverview
Is T43.594S a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report poisoning by other antipsychotics and neuroleptics, undetermined, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character S in T43.594S mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the poisoning by other antipsychotics and neuroleptics, undetermined itself has resolved, not the original event.
What MS-DRG does T43.594S group to?
When poisoning by other antipsychotics and neuroleptics, undetermined, sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 922, 923, with relative weights from 1.0177 to 1.7494 depending on complications. Higher weights mean higher Medicare reimbursement.
Is T43.594S exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for poisoning by other antipsychotics and neuroleptics, undetermined, sequela on inpatient claims.
What is the ICD-9 equivalent of T43.594S?
Under the General Equivalence Mappings, poisoning by other antipsychotics and neuroleptics, undetermined, sequela converts to ICD-9-CM 909.0 (late eff drug poisoning) and E989 (late eff inj-undet circ). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
