1. ICD-10-CM Codes
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2. S00-T88
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3. T66-T78
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4. T78-
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5. 2023 ICD-10-CM Diagnosis Code T78.40

2023 ICD-10-CM Diagnosis Code T78.40

Allergy, unspecified

2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code

• T78.40 should not be used for reimbursement purposes as there are multiple codes below it that contain a greater level of detail.
• The 2023 edition of ICD-10-CM T78.40 became effective on October 1, 2022.
• This is the American ICD-10-CM version of T78.40 - other international versions of ICD-10 T78.40 may differ.

• A disorder characterized by an adverse local or general response from exposure to an allergen.
• A local or general reaction of an organism following contact with a specific allergen to which it has been previously exposed and to which it has become sensitized.
• Altered reactivity to an antigen, which can result in pathologic reactions upon subsequent exposure to that particular antigen.
• An allergy is a reaction of 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
  • pollen
  • dust mites
  • mold spores
  • pet dander
  • food
  • insect stings
  • medicines
  how do you get allergies? scientists think both genes and the environment have something to do with it. Normally, your immune system fights germs. It is your body's defense system. In most allergic reactions, however, it is responding to a false alarm.allergies can cause a runny nose, sneezing, itching, rashes, swelling or asthma. Symptoms vary. Although allergies can make you feel bad, they usually won't kill you. However, a severe reaction called anaphylaxis is life-threatening.
• An exaggerated response by the immune system to a drug or other substance.
• An inflammatory response to an exogenous environmental antigen or an endogenous antigen initiated by the adaptive immune system. [goc:jal, isbn:0781735149]
• Functions of the body's response of increased sensitization to foreign substances, such as in sensitivities to different antigens.
• Hypersensitivity to an agent caused by an immunologic response to an initial exposure
• Hypersensitivity; a local or general reaction of an organism following contact with a specific allergen to which it has been previously exposed and to which it has become sensitized.
• Known to have allergic reactions to particular substance(s)
• State of previously immunized body in which tissue damage results from the immune response to a further dose of antigen.

• 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
• 2017 (effective 10/1/2016): No change
• 2018 (effective 10/1/2017): No change
• 2019 (effective 10/1/2018): No change
• 2020 (effective 10/1/2019): No change
• 2021 (effective 10/1/2020): No change
• 2022 (effective 10/1/2021): No change
• 2023 (effective 10/1/2022): No change

• Type 1 Excludes: L24
  , L23
  , L27
  , L25
  ICD-10-CM Diagnosis Code L24

  Irritant contact dermatitis

  2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code

  Type 1 Excludes

  • allergy NOS (T78.40)
  • contact dermatitis NOS (L25.9)
  • dermatitis NOS (L30.9)

  Type 2 Excludes

  • allergic contact dermatitis (L23.-)
  • dermatitis due to substances taken internally (L27.-)
  • dermatitis of eyelid (H01.1-)
  • diaper dermatitis (L22)
  • eczema of external ear (H60.5-)
  • perioral dermatitis (L71.0)
  • radiation-related disorders of the skin and subcutaneous tissue (L55-L59)
  ICD-10-CM Diagnosis Code L23

  Allergic contact dermatitis

  2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code

  Type 1 Excludes

  • allergy NOS (T78.40)
  • contact dermatitis NOS (L25.9)
  • dermatitis NOS (L30.9)

  Type 2 Excludes

  • dermatitis due to substances taken internally (L27.-)
  • dermatitis of eyelid (H01.1-)
  • diaper dermatitis (L22)
  • eczema of external ear (H60.5-)
  • irritant contact dermatitis (L24.-)
  • perioral dermatitis (L71.0)
  • radiation-related disorders of the skin and subcutaneous tissue (L55-L59)
  ICD-10-CM Diagnosis Code L27

  Dermatitis due to substances taken internally

  2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code

  Type 1 Excludes

  • allergy NOS (T78.40)

  Type 2 Excludes

  • adverse food reaction, except dermatitis (T78.0-T78.1)
  • contact dermatitis (L23-L25)
  • drug photoallergic response (L56.1)
  • drug phototoxic response (L56.0)
  • urticaria (L50.-)
  ICD-10-CM Diagnosis Code L25

  Unspecified contact dermatitis

  2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code

  Type 1 Excludes

  • allergic contact dermatitis (L23.-)
  • allergy NOS (T78.40)
  • dermatitis NOS (L30.9)
  • irritant contact dermatitis (L24.-)

  Type 2 Excludes

  • dermatitis due to ingested substances (L27.-)
  • dermatitis of eyelid (H01.1-)
  • eczema of external ear (H60.5-)
  • perioral dermatitis (L71.0)
  • radiation-related disorders of the skin and subcutaneous tissue (L55-L59)

• Allergy, allergic (reaction) (to) T78.40
  • drug, medicament & biological (any) (external) (internal) T78.40
• Hypersensitive, hypersensitiveness, hypersensitivity - see also Allergy
  • reaction T78.40

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.