> ## 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`


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