FHIR AllergyIntolerance Resource (R4)

AllergyIntolerance records a patient's propensity to an adverse reaction to a substance: drug allergies, food intolerances and so on. Element table, search parameters, example JSON and FHIRPath for FHIR R4.

FHIR AllergyIntolerance Resource (R4) — part of the free FHIR Toolbox library.
Runs entirely in your browser: your FHIR data is never uploaded to a server.

Overview

AllergyIntolerance records a patient's propensity to an adverse reaction to a substance: drug allergies, food intolerances and so on. It carries the substance (code), clinicalStatus, verification, criticality and any observed reactions.

Elements

Element	Type	Cardinality	Description
AllergyIntolerance.identifier	Identifier	0..*	External ids for this item
AllergyIntolerance.clinicalStatus	CodeableConcept	0..1	active \| inactive \| resolved
AllergyIntolerance.verificationStatus	CodeableConcept	0..1	unconfirmed \| confirmed \| refuted \| entered-in-error
AllergyIntolerance.type	code	0..1	allergy \| intolerance - Underlying mechanism (if known)
AllergyIntolerance.category	code	0..*	food \| medication \| environment \| biologic
AllergyIntolerance.criticality	code	0..1	low \| high \| unable-to-assess
AllergyIntolerance.code	CodeableConcept	0..1	Code that identifies the allergy or intolerance
AllergyIntolerance.patient	Reference	1..1	Who the sensitivity is for
AllergyIntolerance.encounter	Reference	0..1	Encounter when the allergy or intolerance was asserted
AllergyIntolerance.onset[x]	dateTime \| Age \| Period \| Range \| string	0..1	When allergy or intolerance was identified
AllergyIntolerance.recordedDate	dateTime	0..1	Date first version of the resource instance was recorded
AllergyIntolerance.recorder	Reference	0..1	Who recorded the sensitivity
AllergyIntolerance.asserter	Reference	0..1	Source of the information about the allergy
AllergyIntolerance.lastOccurrence	dateTime	0..1	Date(/time) of last known occurrence of a reaction
AllergyIntolerance.note	Annotation	0..*	Additional text not captured in other fields
AllergyIntolerance.reaction	BackboneElement	0..*	Adverse Reaction Events linked to exposure to substance
AllergyIntolerance.reaction.id	String	0..1	Unique id for inter-element referencing
AllergyIntolerance.reaction.extension	Extension	0..*	Additional content defined by implementations
AllergyIntolerance.reaction.modifierExtension	Extension	0..*	Extensions that cannot be ignored even if unrecognized
AllergyIntolerance.reaction.substance	CodeableConcept	0..1	Specific substance or pharmaceutical product considered to be responsible for event
AllergyIntolerance.reaction.manifestation	CodeableConcept	1..*	Clinical symptoms/signs associated with the Event
AllergyIntolerance.reaction.description	string	0..1	Description of the event as a whole
AllergyIntolerance.reaction.onset	dateTime	0..1	Date(/time) when manifestations showed
AllergyIntolerance.reaction.severity	code	0..1	mild \| moderate \| severe (of event as a whole)
AllergyIntolerance.reaction.exposureRoute	CodeableConcept	0..1	How the subject was exposed to the substance
AllergyIntolerance.reaction.note	Annotation	0..*	Text about event not captured in other fields

Example JSON (R4)

{
  "resourceType": "AllergyIntolerance",
  "id": "example",
  "clinicalStatus": {
    "coding": [
      {
        "system": "http://terminology.hl7.org/CodeSystem/allergyintolerance-clinical",
        "code": "active"
      }
    ]
  },
  "verificationStatus": {
    "coding": [
      {
        "system": "http://terminology.hl7.org/CodeSystem/allergyintolerance-verification",
        "code": "confirmed"
      }
    ]
  },
  "type": "allergy",
  "category": [
    "medication"
  ],
  "criticality": "high",
  "code": {
    "coding": [
      {
        "system": "http://www.nlm.nih.gov/research/umls/rxnorm",
        "code": "7980",
        "display": "Penicillin G"
      }
    ]
  },
  "patient": {
    "reference": "Patient/example"
  },
  "reaction": [
    {
      "manifestation": [
        {
          "coding": [
            {
              "system": "http://snomed.info/sct",
              "code": "39579001",
              "display": "Anaphylaxis"
            }
          ]
        }
      ],
      "severity": "severe"
    }
  ]
}

FHIRPath

AllergyIntolerance.code.coding.display — The substance
AllergyIntolerance.criticality — Potential seriousness
AllergyIntolerance.reaction.severity — Severity of each reaction

Common validation errors

Using R4's type code against R5, where type is a CodeableConcept, and reaction.manifestation is CodeableReference.
Sending category as a string. It is an array of codes (food | medication | environment | biologic).
Recording “no known allergies” as an AllergyIntolerance with a made-up substance. Use the dedicated “no known allergy” code.

FHIR Toolbox is a free, privacy-first collection of HL7 FHIR utilities by Omindra Labs. Every tool performs zero-server processing — your health data never leaves your device.