2027 ICD-10-CM Diagnosis Code Z91.09Other allergy status, other than to drugs and biological substances
Z91.09 is a billable ICD-10-CM diagnosis code for other allergy status, other than to drugs and biological substances. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 951. The code is not accepted as a principal diagnosis by the Medicare Code Editor and exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified status.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for Z91.09.
Present on Admission (POA)Billing
Z91.09 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Persons with potential health hazards related to family and personal history and certain conditions influencing health status (Z77-Z99).
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Allergy to aluminum
- Allergy to animal protein
- Allergy to bird protein
- Allergy to cattle protein
- Allergy to citric acid
- Allergy to Dermatophagoides farinae protein
- Allergy to Dermatophagoides pteronyssinus protein
- Allergy to dimethicone
- Allergy to domestic cat protein
- Allergy to domestic dog protein
- Allergy to domestic Guinea pig protein
- Allergy to dust
- Allergy to dust mite protein
- Allergy to fungus
- Allergy to horse protein
- Allergy to metal and/or metal compound
- Allergy to mineral oil
- Allergy to mugwort pollen
- Allergy to multiple allergens
- Allergy to paraffin
- Allergy to plant
- Allergy to plant fiber
- Allergy to pollen
- Allergy to pyrethroid
- Allergy to rubber
- Allergy to rust protein
- Allergy to silicone
- Allergy to terpene
- Allergy to tree resin
- Allergy to tropomyosin
- Allergy to wall pellitory pollen
- Allergy to weed pollen
- Allergy to white paraffin
- Allergy to wild rabbit protein
- Allergy to wood dust
- Allergy to wool
- Allergy to wool alcohol
- Allergy to yellow paraffin
- Diffuse dermatitis
- H/O: non-drug allergy
- Severe dermatitis, multiple allergies, metabolic wasting syndrome
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Z91.09: its own notes plus those printed at Z91.0, Z91, block Z77-Z99, and Chapter 21. A note printed at a category, block or chapter applies to every code under it.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- Allergy status to drugs, medicaments, and biological substances (Z88.-)
Code Also
A second code may be needed to fully describe the condition; the note gives no sequencing direction.
Notes
General instructions on how these codes are used.
- Z codes represent reasons for encounters. A corresponding procedure code must accompany a Z code if a procedure is performed. Categories Z00-Z99 are provided for occasions when circumstances other than a disease, injury or external cause classifiable to categories A00-Y89 are recorded as 'diagnoses' or 'problems'. This can arise in two main ways:
- (a) When a person who may or may not be sick encounters the health services for some specific purpose, such as to receive limited care or service for a current condition, to donate an organ or tissue, to receive prophylactic vaccination (immunization), or to discuss a problem which is in itself not a disease or injury.
- (b) When some circumstance or problem is present which influences the person's health status but is not in itself a current illness or injury.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name Z91.09, its category, or a range that includes it.
Excludes2 1
These codes carry an Excludes2 note naming Z91.09: its condition is not part of those codes, and both may be reported when the patient has both.
Use Additional Code 1
These codes say to use an additional code from the note, and Z91.09 is one of the codes named.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
personal (of) See Also: History, family (of);
specified NEC Z91.09
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Allergy
An allergy is a reaction by your immune system to something that does not bother most other people. People who have allergies often are sensitive to more than one thing. Substances that often cause reactions are:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert Z91.09 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About Z91.09Overview
What is the ICD-10 code for other allergy status, other than to drugs and biological substances?
The ICD-10-CM code for other allergy status, other than to drugs and biological substances is Z91.09 (sometimes written as Z9109). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is Z91.09 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report other allergy status, other than to drugs and biological substances on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does Z91.09 group to?
On inpatient claims, other allergy status, other than to drugs and biological substances maps to MS-DRG 951 (other Factors Influencing Health Status), which carries a relative weight of 0.5574. Higher weights mean higher Medicare reimbursement.
Can Z91.09 be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because other allergy status, other than to drugs and biological substances describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.
Is Z91.09 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 other allergy status, other than to drugs and biological substances on inpatient claims. The code appears in the Persons with potential health hazards related to family and personal history and certain conditions influencing health status (Z77-Z99) range of the CMS exempt list.
