> ## 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_extension

Normalized `AllergyIntolerance.extension[]` property on the [AllergyIntolerance](https://hl7.org/fhir/R4/allergyintolerance.html) FHIR resource.

**Primary Keys:**

* allergyintolerance\_extension\_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\_extension\_id | varchar   | Unique identifier for the extension row                |
| allergyintolerance\_id            | varchar   | FK to the parent allergyintolerance record             |
| extension\_rank†                  | int       | 1-based position of this extension in the source array |
| url                               | varchar   | Extension URL identifying the extension type           |
| valuestring                       | varchar   | String value                                           |
| valueboolean                      | bool      | Boolean value                                          |
| valuecode                         | varchar   | Code value                                             |
| valuedatetime                     | datetime  | Datetime value                                         |
| valueinteger                      | int       | Integer value                                          |
| valuedecimal                      | numeric   | Decimal value                                          |
| valuecoding\_code                 | varchar   | Coding code value                                      |
| valuecoding\_display              | varchar   | Coding display text                                    |
| valuecoding\_system               | varchar   | Coding system URI                                      |
| valuecodeableconcept\_text        | varchar   | Free-text description of the value                     |
| valuereference\_reference         | varchar   | Reference value                                        |

**Related Tables:**

**Parent:**

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

**Child:**

* [allergyintolerance\_extension\_vcc\_coding](/medical-api/handling-data/schema-v100/allergyintolerance/extension_vcc_coding)