AdverseEvent — Adverse events and vigilance

Medication adverse reaction, healthcare-associated infection, device failure: AdverseEvent is the pivot resource for reporting, tracking and declaring adverse events along the care pathway.

Purpose

AdverseEvent describes an undesirable event linked to care, potentially with regulatory implications (FDA MedWatch, EMA EudraVigilance, ANSM declaration). It covers multiple categories: medication reaction (ADR), product incident (medical device), procedure error, occupational exposure, sentinel event.

AdverseEvent is distinct from Condition: Condition describes a diagnosis or general health problem, AdverseEvent specifically describes an event that caused harm and may be subject to regulatory reporting.

Key fields

JSON example

Serious allergic reaction to a suspected medication:

{
  "resourceType": "AdverseEvent",
  "id": "example",
  "identifier": [{
    "system": "http://acme.com/ids/patients/risks",
    "value": "49476534"
  }],
  "status": "completed",
  "actuality": "actual",
  "category": [{
    "coding": [{
      "system": "http://terminology.hl7.org/CodeSystem/adverse-event-category",
      "code": "product-use-error",
      "display": "Product Use Error"
    }]
  }],
  "code": {
    "coding": [{
      "system": "http://snomed.info/sct",
      "code": "304386008",
      "display": "Allergic reaction"
    }]
  },
  "subject": { "reference": "Patient/example" },
  "occurrenceDateTime": "2026-05-14T09:25:30+02:00",
  "detected": "2026-05-14T09:30:00+02:00",
  "recordedDate": "2026-05-14T10:00:00+02:00",
  "seriousness": {
    "coding": [{
      "system": "http://terminology.hl7.org/CodeSystem/adverse-event-seriousness",
      "code": "serious",
      "display": "Serious"
    }]
  },
  "outcome": [{
    "coding": [{
      "system": "http://terminology.hl7.org/CodeSystem/adverse-event-outcome",
      "code": "recovered"
    }]
  }],
  "recorder": { "reference": "Practitioner/example" },
  "suspectEntity": [{
    "instance": {
      "reference": { "reference": "Medication/example" }
    }
  }]
}

Common pitfalls

• Confusing AdverseEvent and AllergyIntolerance — AllergyIntolerance describes a future propensity (sensitisation), AdverseEvent describes a concrete past event.
• Missing actuality — mandatory. Without it, the receiver cannot tell a near-miss from a real event.
• Multiple unrelated suspectEntity — declaring several potential causes is allowed but causality must be marked via causality (doseRelation, likelihood...).
• Non-anonymised patient data for reporting — for pharmacovigilance flows, anonymise and use subject on a pseudonymised Patient.

Related resources

• AllergyIntolerance — known allergy propensity.
• Condition — general diagnosis.
• MedicationRequest, MedicationAdministration — suspect medication.
• Device — suspect device.
• ResearchStudy — linked clinical studies (phase 4 pharmacovigilance).