Z91.13Patient's unintentional underdosing of medication regimen

Z91.13 is the ICD-10-CM diagnosis code for patient's unintentional underdosing of medication regimen. It belongs to category Z91 (personal risk factors, not elsewhere classified), block Z77-Z99 (persons with potential health hazards related to family and personal history and certain conditions influencing health status) and chapter 21 (factors influencing health status and contact with health services). It is a header code, so it can't be reported by itself; one of its 2 subcodes must be used instead.

Within Z91.1 (patient's noncompliance with medical treatment and regimen), Z91.13 is specifically for patient's unintentional underdosing of medication regimen. Related codes cover noncompliance with dietary regimen (Z91.11), intentional underdosing of medication regimen (Z91.12), other noncompliance with medication regimen (Z91.14), noncompliance with renal dialysis (Z91.15) and noncompliance with other medical treatment and regimen (Z91.19).

To report this condition, pick the subcode that matches the documentation: Z91.130 (due to age-related debility) and Z91.138 (for other reason).

Code first: underdosing of medication (T36-T50) with fifth or sixth character 6.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.