> ## 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 > Risk of harmful or undesirable, physiological response which is unique to an individual and associated with exposure to a substance. ## Properties | Name | Required | Type | Description | | ------------------- | -------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------- | | identifier | No | [Identifier](/medical-api/fhir/data-types/identifier)\[] | External ids for this item | | clinicalStatus | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | active / inactive / resolved | | verificationStatus | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | unconfirmed / confirmed / refuted / entered-in-error | | type | No | code | allergy / intolerance - Underlying mechanism (if known) | | category | No | code\[] | food / medication / environment / biologic | | criticality | No | code | low / high / unable-to-assess | | code | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | Code that identifies the allergy or intolerance | | patient | Yes | Reference\<[Patient](/medical-api/fhir/resources/patient)> | Who the sensitivity is for | | encounter | No | Reference\<[Encounter](/medical-api/fhir/resources/encounter)> | Encounter when the allergy or intolerance was asserted | | onset\[x] | No | dateTime, [Age](/medical-api/fhir/data-types/age), [Period](/medical-api/fhir/data-types/period), [Range](/medical-api/fhir/data-types/range), string | When allergy or intolerance was identified | | recordedDate | No | dateTime | Date first version of the resource instance was recorded | | recorder | No | Reference\<[Practitioner](/medical-api/fhir/resources/practitioner) / [PractitionerRole](/medical-api/fhir/resources/practitionerrole) / [Patient](/medical-api/fhir/resources/patient) / [RelatedPerson](/medical-api/fhir/resources/relatedperson)> | Who recorded the sensitivity | | asserter | No | Reference\<[Patient](/medical-api/fhir/resources/patient) / [RelatedPerson](/medical-api/fhir/resources/relatedperson) / [Practitioner](/medical-api/fhir/resources/practitioner) / [PractitionerRole](/medical-api/fhir/resources/practitionerrole)> | Source of the information about the allergy | | lastOccurrence | No | dateTime | Date(/time) of last known occurrence of a reaction | | note | No | [Annotation](/medical-api/fhir/data-types/annotation)\[] | Additional text not captured in other fields | | reaction | No | AllergyIntoleranceReaction | Adverse Reaction Events linked to exposure to 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 | | - substance | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | Specific substance or pharmaceutical product considered to be responsible for event | | - manifestation | Yes | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept)\[] | Clinical symptoms/signs associated with the Event | | - description | No | string | Description of the event as a whole | | - onset | No | dateTime | Date(/time) when manifestations showed | | - severity | No | code | mild / moderate / severe (of event as a whole) | | - exposureRoute | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | How the subject was exposed to the substance | | - note | No | [Annotation](/medical-api/fhir/data-types/annotation)\[] | Text about event not captured in other fields | ## Search Parameters | Name | Type | Description | Expression | | ------------------- | --------- | -------------------------------------------------------- | ----------------------------------------- | | asserter | reference | Source of the information about the allergy | AllergyIntolerance.asserter | | category | token | food / medication / environment / biologic | AllergyIntolerance.category | | clinical-status | token | active / inactive / resolved | AllergyIntolerance.clinicalStatus | | code | token | Code that identifies the allergy or intolerance | AllergyIntolerance.code | | criticality | token | low / high / unable-to-assess | AllergyIntolerance.criticality | | date | date | Date first version of the resource instance was recorded | AllergyIntolerance.recordedDate | | identifier | token | External ids for this item | AllergyIntolerance.identifier | | last-date | date | Date(/time) of last known occurrence of a reaction | AllergyIntolerance.lastOccurrence | | manifestation | token | Clinical symptoms/signs associated with the Event | AllergyIntolerance.reaction.manifestation | | onset | date | Date(/time) when manifestations showed | AllergyIntolerance.reaction.onset | | patient | reference | Who the sensitivity is for | AllergyIntolerance.patient | | recorder | reference | Who recorded the sensitivity | AllergyIntolerance.recorder | | route | token | How the subject was exposed to the substance | AllergyIntolerance.reaction.exposureRoute | | severity | token | mild / moderate / severe (of event as a whole) | AllergyIntolerance.reaction.severity | | type | token | allergy / intolerance - Underlying mechanism (if known) | AllergyIntolerance.type | | verification-status | token | unconfirmed / confirmed / refuted / entered-in-error | AllergyIntolerance.verificationStatus | ## 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 [AllergyIntolerance](https://www.hl7.org/fhir/StructureDefinition/AllergyIntolerance).