T78.4 is the ICD-10 code for Allergy, unspecified. It is a four-character subcategory of T78 (Adverse effects, not elsewhere classified), the most specific level in the WHO edition. It belongs to the block T66–T78 (Other and unspecified effects of external causes) in Chapter XIX, Injury, poisoning and certain other consequences of external causes.
- Code type
- Subcategory (4 characters)
- Chapter
- XIX · S00–T98
- Classification
- WHO ICD-10, 2019 version
What T78.4 includes
Conditions and terms that are coded here.
- Allergic reaction NOS
- Hypersensitivity NOS
- Idiosyncracy NOS
What T78.4 excludes
Conditions that look similar but belong under another code.
T78.4 in national editions
Countries report with their own edition of ICD-10. Most keep the WHO code and add more specific codes beneath it.
T78.4Uspesifisert allergi
DT784Allergi UNS
T78.4Määrittämätön allergia
T78.4Allergie, nicht näher bezeichnet
T78.4Allergie, sans précision
T78.4allergie, niet-gespecificeerd
Listed through more specific codes:
- T78.40XAAllergy, unspecified, initial encounter
- T78.40XDAllergy, unspecified, subsequent encounter
- T78.40XSAllergy, unspecified, sequela
- T78.41XAArthus phenomenon, initial encounter
- T78.41XDArthus phenomenon, subsequent encounter
- T78.41XSArthus phenomenon, sequela
- T78.49XAOther allergy, initial encounter
- T78.49XDOther allergy, subsequent encounter
- and 1 more national subcodes
Based on the World Health Organization’s International Statistical Classification of Diseases and Related Health Problems, 10th revision (ICD-10), 2019 version, and the national editions published by each country’s health authority. This page is a reference, not coding advice; follow your national coding rules when you report.
Look up another code
Stop looking codes up by hand
Docdemic listens to the consultation, writes the note and suggests the diagnosis and procedure codes that fit it, each one checked against your country’s official code list.
Try Docdemic free