ICD-10-CM 2027
ICD-10 code for allergy
From the official ICD-10-CM alphabetic index entry “Allergy, allergic (reaction) (to)”. Page updated September 29, 2026.
About coding allergy
The ICD-10-CM code for allergy is T78.40 (Allergy, unspecified). The official index lists 99 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on T78.40.
Within T78.4, choose T78.40 (Allergy, unspecified) only when documentation doesn't support a more specific option: Arthus phenomenon (T78.41) and other allergy (T78.49).
Codes in this range require a 7th character: A for initial encounter, D for subsequent encounter and S for sequela. Use placeholder "X" characters to fill any empty positions before the 7th character.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
More specific allergy codes (official index)
- air-borne substance NEC (rhinitis) J30.89 — Other allergic rhinitis
- alveolitis (extrinsic) J67.9 — Hypersensitivity pneumonitis due to unspecified organic dust
- due to
- Aspergillus clavatus J67.4 — Maltworker's lung
- Cryptostroma corticale J67.6 — Maple-bark-stripper's lung
- organisms (fungal, thermophilic actinomycete) growing in ventilation (air conditioning) systems J67.7 — Air conditioner and humidifier lung
- specified type NEC J67.8 — Hypersensitivity pneumonitis due to other organic dusts
- anaphylactic reaction or shock T78.2 — Anaphylactic shock, unspecified
- angioneurotic edema T78.3 — Angioneurotic edema
- animal (dander) (epidermal) (hair) (rhinitis) J30.81 — Allergic rhinitis due to animal (cat) (dog) hair and dander
- bee sting (anaphylactic shock) T63.44 — Toxic effect of venom of bees
- biological
- colitis K52.29 — Other allergic and dietetic gastroenteritis and colitis
- dairy products T78.119 — Other adverse food reaction due to milk and dairy products with baked milk tolerance/reactivity, unspecified
- with
- reactivity to baked milk T78.111 — Other adverse food reaction due to milk and dairy products with reactivity to baked milk
- tolerance to baked milk T78.110 — Other adverse food reactions due to milk and dairy products with tolerance to baked milk
- anaphylactic reaction T78.079 — Anaphylactic reaction due to milk and dairy products, unspecified
- with
- reactivity to baked milk T78.071 — Anaphylactic reaction due to milk and dairy products with reactivity to baked milk
- tolerance to baked milk T78.070 — Anaphylactic reaction due to milk and dairy products with tolerance to baked milk
- dander (animal) (rhinitis) J30.81 — Allergic rhinitis due to animal (cat) (dog) hair and dander
- dandruff (rhinitis) J30.81 — Allergic rhinitis due to animal (cat) (dog) hair and dander
- dental restorative material (existing) K08.55 — Allergy to existing dental restorative material
- dermatitis
- diathesis
- drug, medicament & biological (any) (external) (internal) T78.40 — Allergy, unspecified
- correct substance properly administered
- wrong substance given or taken NEC (by accident)
- due to pollen J30.1 — Allergic rhinitis due to pollen
- dust (house) (stock) (rhinitis) J30.89 — Other allergic rhinitis
- with asthma
- eczema
- eggs
- adverse reaction NEC T78.129 — Other adverse food reaction due to egg with baked egg tolerance/reactivity, unspecified
- with
- reactivity to baked egg T78.121 — Other adverse food reaction due to egg with reactivity to baked egg
- tolerance to baked egg T78.120 — Other adverse food reaction due to egg with tolerance to baked egg
- anaphylactic reaction T78.089 — Anaphylactic reaction due to eggs, unspecified
- with
- reactivity to baked egg T78.081 — Anaphylactic reaction due to egg with reactivity to baked egg
- tolerance to baked egg T78.080 — Anaphylactic reaction due to egg with tolerance to baked egg
- epidermal (animal) (rhinitis) J30.81 — Allergic rhinitis due to animal (cat) (dog) hair and dander
- feathers (rhinitis) J30.89 — Other allergic rhinitis
- food (any) (ingested) NEC T78.19 — Other adverse food reactions, not elsewhere classified
- anaphylactic shock
- dermatitis
- dietary counseling and surveillance Z71.3 — Dietary counseling and surveillance
- in contact with skin L23.6 — Allergic contact dermatitis due to food in contact with the skin
- rhinitis J30.5 — Allergic rhinitis due to food
- status (without reaction) Z91.018 — Allergy to other foods
- beef Z91.014 — Allergy to mammalian meats
- eggs Z91.0120 — Allergy to eggs, unspecified
- with
- reactivity to baked egg Z91.0122 — Allergy to eggs with reactivity to baked egg
- tolerance to baked egg Z91.0121 — Allergy to eggs with tolerance to baked egg
- lamb Z91.014 — Allergy to mammalian meats
- mammalian meats Z91.014 — Allergy to mammalian meats
- milk products Z91.0110 — Allergy to milk products, unspecified
- with
- reactivity to baked milk Z91.0112 — Allergy to milk products with reactivity to baked milk
- tolerance to baked milk Z91.0111 — Allergy to milk products with tolerance to baked milk
- peanuts Z91.010 — Allergy to peanuts
- pork Z91.014 — Allergy to mammalian meats
- red meats Z91.014 — Allergy to mammalian meats
- seafood Z91.013 — Allergy to seafood
- specified NEC Z91.018 — Allergy to other foods
- gastrointestinal
- meaning colitis K52.29 — Other allergic and dietetic gastroenteritis and colitis
- meaning gastroenteritis K52.29 — Other allergic and dietetic gastroenteritis and colitis
- meaning other adverse food reaction not elsewhere classified T78.19 — Other adverse food reactions, not elsewhere classified
- grain J30.1 — Allergic rhinitis due to pollen
- grass (hay fever) (pollen) J30.1 — Allergic rhinitis due to pollen
- asthma
- hair (animal) (rhinitis) J30.81 — Allergic rhinitis due to animal (cat) (dog) hair and dander
- history (of)
- horse serum
- inhalant (rhinitis) J30.89 — Other allergic rhinitis
- pollen J30.1 — Allergic rhinitis due to pollen
- kapok (rhinitis) J30.89 — Other allergic rhinitis
- medicine
- milk protein Z91.0110 — Allergy to milk products, unspecified
- with
- reactivity to baked milk Z91.0112 — Allergy to milk products with reactivity to baked milk
- tolerance to baked milk Z91.0111 — Allergy to milk products with tolerance to baked milk
- adverse reaction NEC T78.119 — Other adverse food reaction due to milk and dairy products with baked milk tolerance/reactivity, unspecified
- with
- reactivity to baked milk T78.111 — Other adverse food reaction due to milk and dairy products with reactivity to baked milk
- tolerance to baked milk T78.110 — Other adverse food reactions due to milk and dairy products with tolerance to baked milk
- anaphylactic reaction T78.079 — Anaphylactic reaction due to milk and dairy products, unspecified
- with
- reactivity to baked milk T78.071 — Anaphylactic reaction due to milk and dairy products with reactivity to baked milk
- tolerance to baked milk T78.070 — Anaphylactic reaction due to milk and dairy products with tolerance to baked milk
- dermatitis L27.2 — Dermatitis due to ingested food
- enterocolitis syndrome K52.21 — Food protein-induced enterocolitis syndrome
- enteropathy K52.22 — Food protein-induced enteropathy
- gastroenteritis K52.29 — Other allergic and dietetic gastroenteritis and colitis
- gastroesophageal reflux K21.9 — Gastro-esophageal reflux disease without esophagitis
- with esophagitis (without bleeding) K21.00 — Gastro-esophageal reflux disease with esophagitis, without bleeding
- with bleeding K21.01 — Gastro-esophageal reflux disease with esophagitis, with bleeding
- proctocolitis K52.29 — Other allergic and dietetic gastroenteritis and colitis
- nasal, seasonal due to pollen J30.1 — Allergic rhinitis due to pollen
- pneumonia J82.89 — Other pulmonary eosinophilia, not elsewhere classified
- pollen (any) (hay fever) J30.1 — Allergic rhinitis due to pollen
- asthma
- primrose J30.1 — Allergic rhinitis due to pollen
- primula J30.1 — Allergic rhinitis due to pollen
- proctocolitis K52.29 — Other allergic and dietetic gastroenteritis and colitis
- purpura D69.0 — Allergic purpura
- ragweed (hay fever) (pollen) J30.1 — Allergic rhinitis due to pollen
- asthma
- rose (pollen) J30.1 — Allergic rhinitis due to pollen
- seasonal NEC J30.2 — Other seasonal allergic rhinitis
- Senecio jacobae (pollen) J30.1 — Allergic rhinitis due to pollen
- serum T80.69 — Other serum reaction due to other serum
- anaphylactic shock T80.59 — Anaphylactic reaction due to other serum
- shock (anaphylactic) T78.2 — Anaphylactic shock, unspecified
- due to
- administration of blood and blood products T80.51 — Anaphylactic reaction due to administration of blood and blood products
- adverse effect of correct medicinal substance properly administered T88.6 — Anaphylactic reaction due to adverse effect of correct drug or medicament properly administered
- immunization T80.52 — Anaphylactic reaction due to vaccination
- serum NEC T80.59 — Anaphylactic reaction due to other serum
- vaccination T80.52 — Anaphylactic reaction due to vaccination
- specific NEC T78.49 — Other allergy
- tree (any) (hay fever) (pollen) J30.1 — Allergic rhinitis due to pollen
- asthma
- upper respiratory J30.9 — Allergic rhinitis, unspecified
- urticaria L50.0 — Allergic urticaria
- vaccine
- wheat
Common questions about allergy ICD-10 codes
What is the ICD-10 code for allergy?
- T78.40 — Allergy, unspecified (a header code; report a more specific subcode). More specific codes apply when the documentation supports them: J30.89, J67.9, J67.4, J67.6 and others below.
What is the ICD-10 code for air-borne substance nec allergy?
- J30.89 — Other allergic rhinitis.
What is the ICD-10 code for alveolitis allergy?
- J67.9 — Hypersensitivity pneumonitis due to unspecified organic dust.
What is the ICD-10 code for anaphylactic reaction or shock allergy?
- T78.2 — Anaphylactic shock, unspecified (header code; choose a more specific subcode).
What is the ICD-10 code for angioneurotic edema allergy?
- T78.3 — Angioneurotic edema (header code; choose a more specific subcode).
What is the ICD-10 code for animal allergy?
- J30.81 — Allergic rhinitis due to animal (cat) (dog) hair and dander.
What is the ICD-10 code for bee sting allergy?
- T63.44 — Toxic effect of venom of bees (header code; choose a more specific subcode).
Is T78.40 billable?
- No. T78.40 is a header code. Report one of its more specific subcodes instead.