T78.121CurrentCategory · further specificity required

Other adverse food reaction due to egg with reactivity to baked egg

Code-level instructions

Excludes 1

Other adverse food reaction due to egg with tolerance to baked egg (T78.120)

Chapters 19 · Inherited instructions

Use additional code

code to identify any retained foreign body, if applicable (Z18.-)

T78.1 · Inherited instructions

Use additional code

code to identify the type of reaction, if applicable

Excludes 1

anaphylactic reaction or shock due to adverse food reaction (T78.0-)
anaphylactic reaction due to food (T78.0-)
bacterial food borne intoxications (A05.-)

T66-T78 · Inherited instructions

Code also

, if applicable, place of occurrence, such as:
highway rest stop (Y92.523)
school (private) (public) (state) as the place of occurrence of the external cause (Y92.21-)
service areas as the place of occurrence of the external cause (Y92.52-)
single-family non-institutional (private) house as the place of occurrence of the external cause (Y92.01-)
transport vehicle as the place of occurrence of the external cause (Y92.81-)

T78 · Inherited instructions

A — initial encounter

D — subsequent encounter

S — sequela

Excludes 2 · 9

Chapters 19 · Injury, poisoning and certain other consequences of external causes (S00-T88)

Excludes 2

birth trauma (P10-P15)
obstetric trauma (O70-O71)

T78.1 · Other adverse food reactions, not elsewhere classified

Excludes 2

allergic and dietetic gastroenteritis and colitis (K52.29)
allergic rhinitis due to food (J30.5)
dermatitis due to food in contact with skin (L23.6, L24.6, L25.4)
dermatitis due to ingested food (L27.2)
food protein-induced enterocolitis syndrome (K52.21)
food protein-induced enteropathy (K52.22)

T78 · Adverse effects, not elsewhere classified

Excludes 2

complications of surgical and medical care NEC (T80-T88)

More specific codes

T78.121AOther adverse food reaction due to egg with reactivity to baked egg, initial encounter T78.121DOther adverse food reaction due to egg with reactivity to baked egg, subsequent encounter T78.121SOther adverse food reaction due to egg with reactivity to baked egg, sequela

Claims & coverage

When ICD-10-CM is required

For US diagnosis claims covered by HIPAA, ICD-10-CM is required from October 1, 2015.

Use the service date for outpatient/professional claims and the discharge date for hospital inpatient claims. Earlier encounters use ICD-9-CM; each individual code must also be valid for the applicable date.

Official coding guidelines → · CMS ↗

First observed · 2025-10-01

Code history

Latest recorded change · FY2026 · April

ChangedUnchanged

FY2026 · AprilSelected edition

Effective from 2026-04-01

Inherited rules changed

Other adverse food reaction due to egg with reactivity to baked egg

Category — select a more specific code

CDC/NCHS · FY2026 · April

All editions (3)

All editions	Effective from	Code history
FY2026	2025-10-01	Added
FY2026 · April	2026-04-01	Inherited rules changed
FY2027	2026-10-01	No tabular change

Code-level instructions

Excludes 1

Other adverse food reaction due to egg with tolerance to baked egg (T78.120)

Inherited instructions

Chapters 19 · Injury, poisoning and certain other consequences of external causes (S00-T88)

Excludes 2

birth trauma (P10-P15)
obstetric trauma (O70-O71)

Use additional code

code to identify any retained foreign body, if applicable (Z18.-)

Note

Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.

T78.1 · Other adverse food reactions, not elsewhere classified

Excludes 1

anaphylactic reaction or shock due to adverse food reaction (T78.0-)
anaphylactic reaction due to food (T78.0-)
bacterial food borne intoxications (A05.-)

Excludes 2

allergic and dietetic gastroenteritis and colitis (K52.29)
allergic rhinitis due to food (J30.5)
dermatitis due to food in contact with skin (L23.6, L24.6, L25.4)
dermatitis due to ingested food (L27.2)
food protein-induced enterocolitis syndrome (K52.21)
food protein-induced enteropathy (K52.22)

Use additional code

code to identify the type of reaction, if applicable

T66-T78 · Other and unspecified effects of external causes (T66-T78)

Code also

, if applicable, place of occurrence, such as:
highway rest stop (Y92.523)
school (private) (public) (state) as the place of occurrence of the external cause (Y92.21-)
service areas as the place of occurrence of the external cause (Y92.52-)
single-family non-institutional (private) house as the place of occurrence of the external cause (Y92.01-)
transport vehicle as the place of occurrence of the external cause (Y92.81-)

T78 · Adverse effects, not elsewhere classified

Excludes 2

complications of surgical and medical care NEC (T80-T88)

Seventh character

The appropriate 7th character is to be added to each code from category T78

A — initial encounter

D — subsequent encounter

S — sequela

More specific codes

T78.121AOther adverse food reaction due to egg with reactivity to baked egg, initial encounterBillable / specific T78.121DOther adverse food reaction due to egg with reactivity to baked egg, subsequent encounterBillable / specific T78.121SOther adverse food reaction due to egg with reactivity to baked egg, sequelaBillable / specific

Official index references (1)

Allergy, allergic(reaction) (to) (1)

Allergy, allergic(reaction) (to) › eggs › adverse reaction NEC › with › reactivity to baked eggDisease index

Related codes

Other entries in the same category; these are not automatic substitutes.

Code	Description	Category · further specificity required
T78.120	Other adverse food reaction due to egg with tolerance to baked egg	Category · further specificity required
T78.129	Other adverse food reaction due to egg with baked egg tolerance/reactivity, unspecified	Category · further specificity required

Official titles and instructions are preserved in their source language. Official sources ↗

T78.121CurrentCategory · further specificity required

Other adverse food reaction due to egg with reactivity to baked egg

Code-level instructions

Excludes 1

Other adverse food reaction due to egg with tolerance to baked egg (T78.120)

Chapters 19 · Inherited instructions

Use additional code

code to identify any retained foreign body, if applicable (Z18.-)

T78.1 · Inherited instructions

Use additional code

code to identify the type of reaction, if applicable

Excludes 1

anaphylactic reaction or shock due to adverse food reaction (T78.0-)
anaphylactic reaction due to food (T78.0-)
bacterial food borne intoxications (A05.-)

T66-T78 · Inherited instructions

Code also

, if applicable, place of occurrence, such as:
highway rest stop (Y92.523)
school (private) (public) (state) as the place of occurrence of the external cause (Y92.21-)
service areas as the place of occurrence of the external cause (Y92.52-)
single-family non-institutional (private) house as the place of occurrence of the external cause (Y92.01-)
transport vehicle as the place of occurrence of the external cause (Y92.81-)

T78 · Inherited instructions

A — initial encounter

D — subsequent encounter

S — sequela

Excludes 2 · 9

Chapters 19 · Injury, poisoning and certain other consequences of external causes (S00-T88)

Excludes 2

birth trauma (P10-P15)
obstetric trauma (O70-O71)

T78.1 · Other adverse food reactions, not elsewhere classified

Excludes 2

allergic and dietetic gastroenteritis and colitis (K52.29)
allergic rhinitis due to food (J30.5)
dermatitis due to food in contact with skin (L23.6, L24.6, L25.4)
dermatitis due to ingested food (L27.2)
food protein-induced enterocolitis syndrome (K52.21)
food protein-induced enteropathy (K52.22)

T78 · Adverse effects, not elsewhere classified

Excludes 2

complications of surgical and medical care NEC (T80-T88)

More specific codes

Claims & coverage

When ICD-10-CM is required

For US diagnosis claims covered by HIPAA, ICD-10-CM is required from October 1, 2015.

Official coding guidelines → · CMS ↗

First observed · 2025-10-01

Code history

Latest recorded change · FY2026 · April

ChangedUnchanged

FY2026 · AprilSelected edition

Effective from 2026-04-01

Inherited rules changed

Other adverse food reaction due to egg with reactivity to baked egg

Category — select a more specific code

CDC/NCHS · FY2026 · April

All editions (3)

All editions	Effective from	Code history
FY2026	2025-10-01	Added
FY2026 · April	2026-04-01	Inherited rules changed
FY2027	2026-10-01	No tabular change

Code-level instructions

Excludes 1

Other adverse food reaction due to egg with tolerance to baked egg (T78.120)

Inherited instructions

Chapters 19 · Injury, poisoning and certain other consequences of external causes (S00-T88)

Excludes 2

birth trauma (P10-P15)
obstetric trauma (O70-O71)

Use additional code

code to identify any retained foreign body, if applicable (Z18.-)

Note

Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.

T78.1 · Other adverse food reactions, not elsewhere classified

Excludes 1

anaphylactic reaction or shock due to adverse food reaction (T78.0-)
anaphylactic reaction due to food (T78.0-)
bacterial food borne intoxications (A05.-)

Excludes 2

allergic and dietetic gastroenteritis and colitis (K52.29)
allergic rhinitis due to food (J30.5)
dermatitis due to food in contact with skin (L23.6, L24.6, L25.4)
dermatitis due to ingested food (L27.2)
food protein-induced enterocolitis syndrome (K52.21)
food protein-induced enteropathy (K52.22)

Use additional code

code to identify the type of reaction, if applicable

T66-T78 · Other and unspecified effects of external causes (T66-T78)

Code also

, if applicable, place of occurrence, such as:
highway rest stop (Y92.523)
school (private) (public) (state) as the place of occurrence of the external cause (Y92.21-)
service areas as the place of occurrence of the external cause (Y92.52-)
single-family non-institutional (private) house as the place of occurrence of the external cause (Y92.01-)
transport vehicle as the place of occurrence of the external cause (Y92.81-)

T78 · Adverse effects, not elsewhere classified

Excludes 2

complications of surgical and medical care NEC (T80-T88)

Seventh character

The appropriate 7th character is to be added to each code from category T78

A — initial encounter

D — subsequent encounter

S — sequela

More specific codes

Official index references (1)

Allergy, allergic(reaction) (to) (1)

Allergy, allergic(reaction) (to) › eggs › adverse reaction NEC › with › reactivity to baked eggDisease index

Related codes

Other entries in the same category; these are not automatic substitutes.

Code	Description	Category · further specificity required
T78.120	Other adverse food reaction due to egg with tolerance to baked egg	Category · further specificity required
T78.129	Other adverse food reaction due to egg with baked egg tolerance/reactivity, unspecified	Category · further specificity required

Official titles and instructions are preserved in their source language. Official sources ↗