2026 ICD-10-CM Diagnosis Code T40.993APoisoning by other psychodysleptics [hallucinogens], assault, initial encounter
T40.993A is a billable ICD-10-CM diagnosis code for poisoning by other psychodysleptics [hallucinogens], assault, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 917 through 918. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under External cause codes: intent of injury, assault; External cause codes: poisoning by drug; and Hallucinogen-related disorders.
Code Identity
Code Classification
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 narcotics and psychodysleptics [hallucinogens] (T40). 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
Mescaline
hallucinogenic alkaloid isolated from the flowering heads (peyote) of lophophora (formerly anhalonium) williamsii, a mexican cactus used in indian religious rites and as an experimental psychotomimetic. among its cellular effects are agonist actions at some types of serotonin receptors. it has no accepted therapeutic uses although it is legal for religious use by members of the native american church.Phencyclidine
a hallucinogen formerly used as a veterinary anesthetic, and briefly as a general anesthetic for humans. phencyclidine is similar to ketamine in structure and in many of its effects. like ketamine, it can produce a dissociative state. it exerts its pharmacological action through inhibition of nmda receptors (receptors, n-methyl-d-aspartate). as a drug of abuse, it is known as pcp and angel dust.Phencyclidine Abuse
the misuse of phencyclidine with associated psychological symptoms and impairment in social or occupational functioning.Receptors, Phencyclidine
specific sites or molecular structures on cell membranes or in cells with which phencyclidine reacts or to which it binds to elicit the specific response of the cell to phencyclidine. studies have demonstrated the presence of multiple receptor sites for pcp. these are the pcp/sigma site, which binds both pcp and psychotomimetic opiates but not certain antipsychotics, and the pcp site, which selectively binds pcp analogs.Psilocybin
the major of two hallucinogenic components of the sacred teonanacatl mushrooms (see psilocybe), the other component being psilocin.
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.
| Substance | Accidental | Self-harm | Assault | Undetermined | Adverse Effect | Underdosing |
|---|---|---|---|---|---|---|
| Bufotenine | T40.991 | T40.992 | T40.993 | T40.994 | – | – |
| Diethyltryptamine (DET) | T40.991 | T40.992 | T40.993 | T40.994 | – | – |
| Hawaiian Woodrose seeds | T40.991 | T40.992 | T40.993 | T40.994 | – | – |
| Heavenly Blue (morning glory) | T40.991 | T40.992 | T40.993 | T40.994 | – | – |
| Magic mushroom | T40.991 | T40.992 | T40.993 | T40.994 | – | – |
| Mescal buttons | T40.991 | T40.992 | T40.993 | T40.994 | – | – |
| Mescaline | T40.991 | T40.992 | T40.993 | T40.994 | – | – |
| Morning glory seeds | T40.991 | T40.992 | T40.993 | T40.994 | – | – |
| Pearly Gates (morning glory seeds) | T40.991 | T40.992 | T40.993 | T40.994 | – | – |
| Peyote | T40.991 | T40.992 | T40.993 | T40.994 | – | – |
| Phencyclidine | T40.991 | T40.992 | T40.993 | T40.994 | T40.995 | T40.996 |
| Psilocin | T40.991 | T40.992 | T40.993 | T40.994 | – | – |
| Psilocybin | T40.991 | T40.992 | T40.993 | T40.994 | – | – |
| Psilocybine | T40.991 | T40.992 | T40.993 | T40.994 | – | – |
| Yohimbic acid | T40.991 | T40.992 | T40.993 | T40.994 | T40.995 | T40.996 |
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 T40.993A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T40.993AOverview
Is T40.993A (Poisoning by other psychodysleptics [hallucinogens], assault) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report poisoning by other psychodysleptics [hallucinogens], assault, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T40.993A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for poisoning by other psychodysleptics [hallucinogens], assault, such as an emergency visit or first evaluation.
What MS-DRG does T40.993A group to?
When poisoning by other psychodysleptics [hallucinogens], assault, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of T40.993A?
Under the General Equivalence Mappings, poisoning by other psychodysleptics [hallucinogens], assault, initial encounter converts to ICD-9-CM 969.6 (poisoning-hallucinogens) and E962.0 (assault-pois w medic agt). 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.
