T78.121 — Other adverse food reaction due to egg with reactivity to baked egg
Is T78.121 billable?
No — T78.121 is a non-billable header code. T78.121 groups more specific codes and cannot be submitted on a claim. A valid ICD-10-CM code must be reported at the highest level of specificity available in its branch. Select one of the 3 billable codes beneath T78.121.
Billable codes under this header
T78.121 at a glance
| Code | T78.121 |
|---|---|
| Description | Other adverse food reaction due to egg with reactivity to baked egg |
| Billable | No — header code |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
How is T78.121 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to T78.121. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Allergy, allergic › eggs › adverse reaction NEC › with › reactivity to baked egg (reaction) (to)
Excludes1 — never code together
The conditions below can never be reported together with T78.121 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
- Other adverse food reaction due to egg with tolerance to baked egg (T78.120)
Excludes1 — never code together — inherited from T78.1
The conditions below can never be reported together with T78.121 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
Use additional code — inherited from Chapter 19
Report an additional code alongside T78.121 to fully describe the condition. T78.121 is sequenced first.
- code to identify any retained foreign body, if applicable (Z18.-)
Use additional code — inherited from T78.1
Report an additional code alongside T78.121 to fully describe the condition. T78.121 is sequenced first.
- code to identify the type of reaction, if applicable
Excludes2 — not included here — inherited from Chapter 19
The conditions below are not part of T78.121, but a patient may have both at the same time. When documentation supports it, T78.121 and the excluded code may both be reported.
Excludes2 — not included here — inherited from T78
The conditions below are not part of T78.121, but a patient may have both at the same time. When documentation supports it, T78.121 and the excluded code may both be reported.
- complications of surgical and medical care NEC (T80-T88)
Excludes2 — not included here — inherited from T78.1
The conditions below are not part of T78.121, but a patient may have both at the same time. When documentation supports it, T78.121 and the excluded code may both be reported.
Code also — inherited from T66-T78
Two codes may be needed to describe the condition fully. Whether T78.121 is sequenced first depends on the reason for the encounter.
- , 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-)
What codes fall under T78.121? (3)
How long has T78.121 existed?
T78.121 first appears in FY2026.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.