The ICD-10 code range T36-T50 is designed to capture incidents of poisoning, adverse effects, and underdosing of drugs, medicaments, and biological substances. This range is comprehensive, covering a wide array of substances, from antibiotics (T36) to hormones and their synthetic substitutes (T38), and even to narcotics and psychodysleptics (T40). These codes are used in a variety of clinical settings, from emergency departments to primary care, and are critical for tracking public health trends, billing, and research.

Key Usage Points:

•Always code for the most specific level of detail available, including the substance involved and the type of encounter.
•Remember to use additional codes to identify any associated withdrawal symptoms from drugs or substances.
•For underdosing, always assign a code explaining the reason from categories Z91.12-, Z91.13-, Z91.14-.
•In the case of poisoning, use additional code(s) for all manifestations of poisonings.
•For adverse effects, the nature of the adverse effect should be identified by use of codes from categories T78.4, T78.5, T80.5 and T88.6.

Coding Guidelines

When to Use:

✓When a patient presents with symptoms due to accidental or intentional overdose of a medication.
✓When a patient experiences an adverse effect from a medication as a result of correct use.
✓When a patient has not taken enough of their prescribed medication, resulting in an underdose.
✓When a patient presents with withdrawal symptoms from a substance.
✓When a patient is seen for follow-up care after being treated for poisoning.

When NOT to Use:

✗When a patient presents with symptoms that are not related to poisoning, adverse effects, or underdosing of a drug.
✗When the patient's condition is due to drug abuse or dependence, not poisoning or underdosing.
✗When the patient's condition is due to an allergic reaction, not an adverse effect.
✗When the substance involved is not a drug, medicament, or biological substance.

Code Exclusions

Always verify exclusions by cross-referencing the patient's clinical documentation and the ICD-10-CM Official Guidelines for Coding and Reporting.

Documentation Requirements

Proper documentation for codes T36-T50 should include the specific substance involved, the type of encounter (initial, subsequent, sequela), and the intent (accidental, intentional self-harm, assault, undetermined). For underdosing, the reason should be documented. For adverse effects, the nature of the adverse effect should be identified.

Clinical Information:

•Specific substance involved
•Type of encounter
•Intent
•Reason for underdosing
•Nature of adverse effect

Supporting Evidence:

•Clinical notes
•Lab results
•Imaging studies
•Patient history

Good Documentation Example:

Patient presented with dizziness and nausea after accidentally taking double her prescribed dose of metoprolol. This is an initial encounter.

Poor Documentation Example:

Patient presented with dizziness and nausea.

Common Documentation Errors:

⚠Not specifying the substance involved
⚠Not indicating the type of encounter
⚠Not documenting the intent
⚠Not providing a reason for underdosing
⚠Not identifying the nature of an adverse effect

Range Statistics

Total Codes

Billable

Complexity:

Medium

Primary Use:Clinical Documentation

Chapter:

Coding Complexity

Medium

Complexity Rating

The complexity of these codes is considered medium due to the need to accurately identify the specific substance involved, determine the type of encounter and intent, and identify the reason for underdosing or the nature of an adverse effect. This requires a thorough understanding of the clinical documentation and the ICD-10-CM Official Guidelines for Coding and Reporting.

Key Factors:

▸Identifying the specific substance involved
▸Determining the type of encounter
▸Determining the intent
▸Identifying the reason for underdosing
▸Identifying the nature of an adverse effect

Specialty Focus

These codes are used across many specialties, but are particularly prevalent in emergency medicine, primary care, and toxicology. They are used to document cases of poisoning, adverse effects, and underdosing, and are critical for tracking public health trends.

Primary Specialties:

Emergency Medicine

40%

Primary Care

30%

Toxicology

30%

Clinical Scenarios:

• A patient presents to the ER after accidentally overdosing on a medication.
• A patient experiences an adverse effect from a medication during a routine check-up.
• A patient has not taken enough of their prescribed medication, resulting in an underdose.
• A patient presents with withdrawal symptoms from a substance during a toxicology consultation.
• A patient is seen for follow-up care in primary care after being treated for poisoning in the ER.

Resources & References

There are several resources available for coding T36-T50, including the ICD-10-CM Official Guidelines for Coding and Reporting, clinical reference materials, and educational resources.

Official Guidelines:

ICD-10-CM Official Guidelines for Coding and Reporting
CDC ICD-10-CM Browser Tool
WHO ICD-10 Browser

Clinical References:

Clinical Pharmacology
UpToDate

Educational Materials:

AAPC ICD-10 Training
AHIMA ICD-10 Training

Frequently Asked Questions

How do I code for a patient who has taken too much of their medication?

You would use a code from the T36-T50 range, specifying the substance involved, the type of encounter (initial, subsequent, sequela), and the intent (accidental, intentional self-harm, assault, undetermined).