2025 ICD-10-CM Diagnosis Code T40.902A

Clinical Classification

Clinical Classifications group individual ICD-10-CM diagnosis codes into broader, clinically meaningful categories. These categories help simplify complex data by organizing related conditions under common clinical themes.

They are especially useful for data analysis, reporting, and clinical decision-making. Even when diagnosis codes differ, similar conditions can be grouped together based on their clinical relevance. Each category is assigned a unique CCSR code that represents a specific clinical concept, often tied to a body system or medical specialty.

Coding Guidelines

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 aplicable episode of care:

• A - initial encounter
• D - subsequent encounter
• S - sequela

MS-DRG Mapping for ICD-10-CM Code T40.902A

Diagnosis-Related Groups (DRGs) are used to classify hospital cases for billing and healthcare management. They help standardize how hospitals and other providers are reimbursed for inpatient care. Patients are grouped based on their principal diagnosis into broader categories called Major Diagnostic Categories (MDCs).

Once assigned to a DRG, the hospital receives a set payment for the patient’s care, regardless of the actual services provided. This fixed rate is intended to cover the typical cost of treating patients within that group. The payment amount depends on the DRG's relative weight, which reflects the expected complexity and cost of care based on the severity of the patient’s condition.

Diagnostic related groups encourage healthcare providers to focus on quality and efficiency in patient care while managing costs effectively. The diagnosis code is present in the following groups for version MS-DRG V42.0 applicable from 10/01/2024 through 09/30/2025.

Convert T40.902A to ICD-9-CM

Below are the ICD-9 codes that most closely match this ICD-10 code, based on the General Equivalence Mappings (GEMs). This ICD-10 to ICD-9 crosswalk tool is helpful for coders who need to reference legacy diagnosis codes for audits, historical claims, or approximate code comparisons.

Table of Drugs and Chemicals

The parent code T40.902 of the current diagnosis code is referenced in the Table of Drugs and Chemicals, this table contains a classification of drugs, industrial solvents, corrosive gases, noxious plants, pesticides, and other toxic agents.

According to ICD-10-CM coding guidelines it is advised to do not code directly from the Table of Drugs and Chemicals, instead always refer back to the Tabular List when doing the initial coding. Each substance in the table is assigned a code according to the poisoning classification and external causes of adverse effects. It is important to use as many codes as necessary to specify all reported drugs, medicinal or chemical substances. If the same diagnosis code describes the causative agent for more than one adverse reaction, poisoning, toxic effect or underdosing, utilize the code only once.

Filter table of drugs and chemicals:

Substance	Poisoning Accidental (unintentional)	Poisoning Accidental (self-harm)	Poisoning Assault	Poisoning Undetermined	Adverse effect	Underdosing
Hallucinogen NOS	T40.901	T40.902	T40.903	T40.904	T40.905	T40.906
Hallucinogen NOS   »specified NEC	T40.901	T40.902	T40.903	T40.904	T40.905	T40.906
Megahallucinogen	T40.901	T40.902	T40.903	T40.904	T40.905	T40.906
Psychodysleptic drug NOS	T40.901	T40.902	T40.903	T40.904	T40.905	T40.906
Psychodysleptic drug NOS   »specified NEC	T40.901	T40.902	T40.903	T40.904	T40.905	T40.906
Psychotomimetic agents	T40.901	T40.902	T40.903	T40.904	T40.905	T40.906

Patient Education

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:

• Prescription or over-the-counter medicines taken in doses that are too high
• Overdoses of illegal drugs
• Carbon monoxide from gas appliances
• Household products, such as laundry powder or furniture polish
• Pesticides
• Indoor or outdoor plants
• Metals such as lead and mercury

The effects of poisoning range from short-term illness to brain damage, coma, and death. To prevent poisoning it is important to use and store products exactly as their labels say. Keep dangerous products where children can't get to them. Treatment for poisoning depends on the type of poison. If you suspect someone has been poisoned, call your local poison control center at 1-800-222-1222 right away.

[Learn More in MedlinePlus]

Self-Harm

What is self-harm?

Self-harm, or self-injury, is when a person hurts his or her own body on purpose. The injuries may be minor, but sometimes they can be severe. They may leave permanent scars or cause serious health problems. Some examples are:

• Cutting yourself (such as using a razor blade, knife, or other sharp object to cut your skin)
• Punching yourself or punching things (like a wall)
• Burning yourself with cigarettes, matches, or candles
• Pulling out your hair
• Poking objects through body openings
• Breaking your bones or bruising yourself

Self-harm is not a mental disorder. It is a behavior - an unhealthy way to cope with strong feelings. However, some of the people who harm themselves do have a mental disorder.

People who harm themselves are usually not trying to attempt suicide. But they are at higher risk of attempting suicide if they do not get help.

Why do people harm themselves?

There are different reasons why people harm themselves. Often, they have trouble coping and dealing with their feelings. They harm themselves to try to:

• Make themselves feel something (because they feel empty or numb inside)
• Block upsetting memories
• Show that they need help
• Release strong feelings that overwhelm them, such as anger, loneliness, or hopelessness
• Punish themselves
• Feel a sense of control

Who is at risk for self-harm?

There are people of all ages who harm themselves, but it usually starts in the teen or early adult years. Self-harm is more common in people who:

• Were abused or went through a trauma as children
• Have mental disorders, such as
  • Depression
  • Eating disorders
  • Post-traumatic stress disorder
  • Certain personality disorders
• Misuse drugs or alcohol
• Have friends who self-harm
• Have low self-esteem

What are the signs of self-harm?

Signs that someone may be hurting themselves include:

• Having frequent cuts, bruises, or scars
• Wearing long sleeves or pants even in hot weather
• Making excuses about injuries
• Having sharp objects around for no clear reason

How can I help someone who self-harms?

If someone you know is self-harming, it is important not to be judgmental. Let that person know that you want to help. If the person is a child or teenager, ask him or her to talk to a trusted adult. If he or she won't do that, talk to a trusted adult yourself. If the person who is self-harming is an adult, suggest mental health counseling.

What the treatments are for self-harm?

There are no medicines to treat self-harming behaviors. But there are medicines to treat any mental disorders that the person may have, such as anxiety and depression. Treating the mental disorder may weaken the urge to self-harm.

Mental health counseling or therapy can also help by teaching the person:

• Problem-solving skills
• New ways to cope with strong emotions
• Better relationship skills
• Ways to strengthen self-esteem

If the problem is severe, the person may need more intensive treatment in a psychiatric hospital or a mental health day program.

[Learn More in MedlinePlus]

Code History

• FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
• FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
• FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
• FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
• FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
• FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
• FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
• FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
• FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016. This was the first year ICD-10-CM was implemented into the HIPAA code set.