> ## Documentation Index
> Fetch the complete documentation index at: https://docs.metriport.com/llms.txt
> Use this file to discover all available pages before exploring further.

# allergyintolerance_reaction

Details about each adverse reaction event linked to the allergy/intolerance (`AllergyIntolerance.reaction[]`).

**Previous version:** [allergy\_intolerance\_reaction](/medical-api/handling-data/schema-v000/allergy-intolerance/reaction)

**Primary Keys:**

* allergyintolerance\_reaction\_id

**Foreign Keys:**

* allergyintolerance\_id - links to the [allergyintolerance](/medical-api/handling-data/schema-v100/allergyintolerance/base) table

<div style={{textAlign: 'right'}}><sub>† Metriport Platform added</sub></div>

| Column                           | Data Type | Description                                                |
| -------------------------------- | --------- | ---------------------------------------------------------- |
| allergyintolerance\_reaction\_id | varchar   | Unique identifier for the reaction                         |
| allergyintolerance\_id           | varchar   | FK to the parent allergyintolerance record                 |
| onset                            | datetime  | Date when the reaction began                               |
| substance\_text                  | varchar   | Free-text description of the substance                     |
| substance\_snomed\_code†         | varchar   | SNOMED CT code for the substance responsible for the event |
| substance\_snomed\_display†      | varchar   | Human-readable SNOMED CT description of the substance      |
| severity                         | varchar   | Severity of the reaction (mild, moderate, severe)          |

**Related Tables:**

**Parent:**

* [allergyintolerance](/medical-api/handling-data/schema-v100/allergyintolerance/base)

**Child:**

* [allergyintolerance\_reaction\_manifestation](/medical-api/handling-data/schema-v100/allergyintolerance/reaction_manifestation)
* [allergyintolerance\_reaction\_substance\_coding](/medical-api/handling-data/schema-v100/allergyintolerance/reaction_substance_coding)

## Version diff

**Renamed**

* `allergy_intolerance_reaction_id` → `allergyintolerance_reaction_id`
* `allergy_intolerance_id` → `allergyintolerance_id`
* `onset_date` → `onset`
* `snomed_code` → `substance_snomed_code`
* `snomed_display` → `substance_snomed_display`

**Moved to separate tables**

* `source_substance_code` → [`allergyintolerance_reaction_substance_coding.code`](/medical-api/handling-data/schema-v100/allergyintolerance/reaction_substance_coding) w/ `code_rank = 1`
* `source_substance_display` → [`allergyintolerance_reaction_substance_coding.display`](/medical-api/handling-data/schema-v100/allergyintolerance/reaction_substance_coding) w/ `code_rank = 1`
* `source_substance_system` → [`allergyintolerance_reaction_substance_coding.system`](/medical-api/handling-data/schema-v100/allergyintolerance/reaction_substance_coding) w/ `code_rank = 1`