ICD-10-CM
ICD-10 code for Allergy, allergic (reaction) (to): T78.40
The ICD-10-CM index points "Allergy, allergic (reaction) (to)" to T78.40, Allergy, unspecified. T78.40 is not billable on its own. Add the 7th character for the encounter, for example T78.40XA, Allergy, unspecified, initial encounter.
Source: CDC ICD-10-CM FY2027 Alphabetic Index file dated June 16, 2026. Publisher page
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Index subterms
A header groups codes and is not billed. A billable code is one you can report.
- J30.89air-borne substance NEC (rhinitis), Other allergic rhinitisBillable
- J67.9alveolitis (extrinsic), Hypersensitivity pneumonitis due to unspecified organic dustBillable
- T78.2anaphylactic reaction or shock, Anaphylactic shock, unspecifiedHeader
- T78.3angioneurotic edemaHeader
- J30.81animal (dander) (epidermal) (hair) (rhinitis), Allergic rhinitis due to animal (cat) (dog) hair and danderBillable
- K52.29colitis, Other allergic and dietetic gastroenteritis and colitisBillable
- T78.119dairy products, Other adverse food reaction due to milk and dairy products with baked milk tolerance/reactivity, unspecifiedHeader
- J30.81dander (animal) (rhinitis), Allergic rhinitis due to animal (cat) (dog) hair and danderBillable
- J30.81dandruff (rhinitis), Allergic rhinitis due to animal (cat) (dog) hair and danderBillable
- K08.55dental restorative material (existing), Allergy to existing dental restorative materialBillable
- T78.40drug, medicament & biological (any) (external) (internal), Allergy, unspecifiedHeader
- J30.1due to pollen, Allergic rhinitis due to pollenBillable
- J30.89dust (house) (stock) (rhinitis), Other allergic rhinitisBillable
- J30.81epidermal (animal) (rhinitis), Allergic rhinitis due to animal (cat) (dog) hair and danderBillable
- J30.89feathers (rhinitis), Other allergic rhinitisBillable
- T78.19food (any) (ingested) NEC, Other adverse food reactions, not elsewhere classifiedHeader
- J30.1grain, Allergic rhinitis due to pollenBillable
- J30.1grass (hay fever) (pollen), Allergic rhinitis due to pollenBillable
- J30.81hair (animal) (rhinitis), Allergic rhinitis due to animal (cat) (dog) hair and danderBillable
- J30.89inhalant (rhinitis), Other allergic rhinitisBillable
- J30.89kapok (rhinitis), Other allergic rhinitisBillable
- Z91.0110milk protein, Allergy to milk products, unspecifiedBillable
- J30.1nasal, seasonal due to pollen, Allergic rhinitis due to pollenBillable
- J82.89pneumonia, Other pulmonary eosinophilia, not elsewhere classifiedBillable
- J30.1pollen (any) (hay fever), Allergic rhinitis due to pollenBillable
- J30.1primrose, Allergic rhinitis due to pollenBillable
- J30.1primula, Allergic rhinitis due to pollenBillable
- K52.29proctocolitis, Other allergic and dietetic gastroenteritis and colitisBillable
- D69.0purpura, Allergic purpuraBillable
- J30.1ragweed (hay fever) (pollen), Allergic rhinitis due to pollenBillable
- J30.1rose (pollen), Allergic rhinitis due to pollenBillable
- J30.2seasonal NEC, Other seasonal allergic rhinitisBillable
- J30.1Senecio jacobae (pollen), Allergic rhinitis due to pollenBillable
- T80.69serum, Other serum reaction due to other serumHeader
- T78.2shock (anaphylactic), Anaphylactic shock, unspecifiedHeader
- T78.49specific NEC, Other allergyHeader
- J30.1tree (any) (hay fever) (pollen), Allergic rhinitis due to pollenBillable
- J30.9upper respiratory, Allergic rhinitis, unspecifiedBillable
- L50.0urticaria, Allergic urticariaBillable
More specific codes in T78
A header groups codes and is not billed. A billable code is one you can report.
- T78Adverse effects, not elsewhere classifiedHeader
- T78.0Anaphylactic reaction due to foodHeader
- T78.00Anaphylactic reaction due to unspecified foodHeader
- T78.01Anaphylactic reaction due to peanutsHeader
- T78.02Anaphylactic reaction due to shellfish (crustaceans)Header
- T78.03Anaphylactic reaction due to other fishHeader
- T78.04Anaphylactic reaction due to fruits and vegetablesHeader
- T78.05Anaphylactic reaction due to tree nuts and seedsHeader
- T78.06Anaphylactic reaction due to food additivesHeader
- T78.07Anaphylactic reaction due to milk and dairy productsHeader
- T78.08Anaphylactic reaction due to eggsHeader
- T78.09Anaphylactic reaction due to other food productsHeader
- T78.1Other adverse food reactions, not elsewhere classifiedHeader
- T78.11Other adverse food reactions due to milk and dairy productsHeader
- T78.12Other adverse food reaction due to eggsHeader
- T78.19Other adverse food reactions, not elsewhere classifiedHeader
- T78.2Anaphylactic shock, unspecifiedHeader
- T78.3Angioneurotic edemaHeader
- T78.4Other and unspecified allergyHeader
- T78.40Allergy, unspecifiedHeader
- T78.41Arthus phenomenonHeader
- T78.49Other allergyHeader
- T78.8Other adverse effects, not elsewhere classifiedHeader
Excludes1
Excludes1 means these codes are not reported together.
From T78.4. A note on a category applies to every code under it.
Excludes2
Excludes2 means the other condition can be reported with this one when both are documented.
From T78. A note on a category applies to every code under it.
Related pages
- T78.40 code detailsNotes, nearby codes, CMS-HCC group
- Category T78Every code under it
- Chapter 19Injury, poisoning and certain other consequences
- ICD-10 codes by conditionA to Z
- Check a list of ICD-10 codes
- Denial code CO-11Diagnosis does not support the procedure
- Denial code CO-146Diagnosis invalid for the date of service
- HCPCS Level II code lookup
Questions
What is the ICD-10 code for Allergy, allergic (reaction) (to)?
The ICD-10-CM index points "Allergy, allergic (reaction) (to)" to T78.40, Allergy, unspecified. T78.40 is not billable on its own. Add the 7th character for the encounter, for example T78.40XA, Allergy, unspecified, initial encounter.
Is T78.40 billable?
No. T78.40 is a header in the FY2027 CDC file. Report a more specific code under it.
What documentation notes apply to T78.40?
The CDC tabular list gives 7 Excludes1 notes (not coded together), 1 Excludes2 note (may be coded together when both are documented) for T78.40 and the categories above it. They are listed on this page.
What chapter is T78.40 in?
Chapter 19. Injury, poisoning and certain other consequences.
When do ICD-10-CM codes change?
Every October 1, with the new fiscal year file. Some years add April 1 updates. This page uses the FY2027 file, effective October 1, 2026.