> ## 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.

# Substance

> A homogeneous material with a definite composition.

## Properties

| Name                | Required | Type                                                                                                                            | Description                                                     |
| ------------------- | -------- | ------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------- |
| identifier          | No       | [Identifier](/medical-api/fhir/data-types/identifier)\[]                                                                        | Unique identifier                                               |
| status              | No       | code                                                                                                                            | active / inactive / entered-in-error                            |
| category            | No       | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept)\[]                                                              | What class/type of substance this is                            |
| code                | Yes      | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept)                                                                 | What substance this is                                          |
| description         | No       | string                                                                                                                          | Textual description of the substance, comments                  |
| instance            | No       | SubstanceInstance                                                                                                               | If this describes a specific package/container of the substance |
| - id                | No       | string                                                                                                                          | Unique id for inter-element referencing                         |
| - extension         | No       | [Extension](/medical-api/fhir/data-types/extension)\[]                                                                          | Additional content defined by implementations                   |
| - modifierExtension | No       | [Extension](/medical-api/fhir/data-types/extension)\[]                                                                          | Extensions that cannot be ignored even if unrecognized          |
| - identifier        | No       | [Identifier](/medical-api/fhir/data-types/identifier)                                                                           | Identifier of the package/container                             |
| - expiry            | No       | dateTime                                                                                                                        | When no longer valid to use                                     |
| - quantity          | No       | [Quantity](/medical-api/fhir/data-types/quantity)                                                                               | Amount of substance in the package                              |
| ingredient          | No       | SubstanceIngredient                                                                                                             | Composition information about the substance                     |
| - id                | No       | string                                                                                                                          | Unique id for inter-element referencing                         |
| - extension         | No       | [Extension](/medical-api/fhir/data-types/extension)\[]                                                                          | Additional content defined by implementations                   |
| - modifierExtension | No       | [Extension](/medical-api/fhir/data-types/extension)\[]                                                                          | Extensions that cannot be ignored even if unrecognized          |
| - quantity          | No       | [Ratio](/medical-api/fhir/data-types/ratio)                                                                                     | Optional amount (concentration)                                 |
| - substance\[x]     | Yes      | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept), Reference\<[Substance](/medical-api/fhir/resources/substance)> | A component of the substance                                    |

## Search Parameters

| Name                 | Type      | Description                                      | Expression                     |
| -------------------- | --------- | ------------------------------------------------ | ------------------------------ |
| category             | token     | The category of the substance                    | Substance.category             |
| code                 | token     | The code of the substance or ingredient          | Substance.code                 |
| container-identifier | token     | Identifier of the package/container              | Substance.instance.identifier  |
| expiry               | date      | Expiry date of package or container of substance | Substance.instance.expiry      |
| identifier           | token     | Unique identifier for the substance              | Substance.identifier           |
| quantity             | quantity  | Amount of substance in the package               | Substance.instance.quantity    |
| status               | token     | active / inactive / entered-in-error             | Substance.status               |
| substance-reference  | reference | A component of the substance                     | Substance.ingredient.substance |

## Inherited Properties

| Name              | Required | Type                                                   | Description                                            |
| ----------------- | -------- | ------------------------------------------------------ | ------------------------------------------------------ |
| id                | No       | string                                                 | Logical id of this artifact                            |
| meta              | No       | [Meta](/medical-api/fhir/data-types/meta)              | Metadata about the resource                            |
| implicitRules     | No       | uri                                                    | A set of rules under which this content was created    |
| language          | No       | code                                                   | Language of the resource content                       |
| text              | No       | [Narrative](/medical-api/fhir/data-types/narrative)    | Text summary of the resource, for human interpretation |
| contained         | No       | Resource\[]                                            | Contained, inline Resources                            |
| extension         | No       | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations          |
| modifierExtension | No       | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored                      |

To view the FHIR specification for this resource, see [Substance](https://www.hl7.org/fhir/StructureDefinition/Substance).