Provides granular per-reaction detail for a single allergy occurrence documented in an associated IAM segment, including the specific reaction code, severity, sensitivity to causative agent, and management actions taken. Introduced in v2.8, it repeats under IAM segments in ADT and allergy-update messages. It enables systems like EHRs and pharmacy applications to exchange structured multi-reaction data for a given allergen.
from zato.hl7v2.v2_9 import IAR
from zato.hl7v2.v2_9 import CWE
iar = IAR()
iar.allergy_reaction_code = CWE(
identifier='HIVES',
text='Hives'
)
iar.allergy_severity_code = CWE(
identifier='MO',
text='Moderate'
)How to construct and work with real-world IAR segments.
Skin reaction to food allergen
from zato.hl7v2.v2_9 import IAR
from zato.hl7v2.v2_9 import CWE
iar = IAR()
iar.allergy_reaction_code = CWE(
identifier='HIVES',
text='Hives'
)
iar.allergy_severity_code = CWE(
identifier='MO',
text='Moderate',
name_of_coding_system='HL70128'
)
iar.sensitivity_to_causative_agent_code = CWE(text='Urticaria on arms and torso')Digestive reaction to supplement
from zato.hl7v2.v2_9 import IAR
from zato.hl7v2.v2_9 import CWE
iar = IAR()
iar.allergy_reaction_code = CWE(
identifier='GI',
text='GI Distress'
)
iar.allergy_severity_code = CWE(
identifier='MI',
text='Mild',
name_of_coding_system='HL70128'
)
iar.sensitivity_to_causative_agent_code = CWE(text='Nausea and stomach cramps')Breathing difficulty from allergen
from zato.hl7v2.v2_9 import IAR
from zato.hl7v2.v2_9 import CWE
iar = IAR()
iar.allergy_reaction_code = CWE(
identifier='RESP',
text='Respiratory'
)
iar.allergy_severity_code = CWE(
identifier='SV',
text='Severe',
name_of_coding_system='HL70128'
)
iar.sensitivity_to_causative_agent_code = CWE(text='Wheezing and shortness of breath')Step-by-step guides for working with HL7 v2 in Zato.
IAR contains allergy reaction information including reaction types, severity, and descriptions for wellness program safety documentation.
Common reaction types include HIVES (skin reaction), GI (gastrointestinal), and RESP (respiratory) reactions.
Use allergy_severity_code field with HL70128 values:
iar.allergy_severity_code = CWE(
identifier='SV',
text='Severe',
name_of_coding_system='HL70128'
)IAM contains the allergy information while IAR contains specific reaction details. Multiple IAR segments can follow an IAM to describe different reactions.
Zato connects to any system that speaks HL7v2 over MLLP or FHIR over REST. This includes Epic, Cerner, Meditech, Allscripts, and other EHR platforms.
Yes, Zato has built-in MLLP support for sending and receiving HL7v2 messages. MLLP channels handle the framing protocol automatically.
Zato supports HL7 v2.9, which is backward compatible with earlier versions including v2.3, v2.5, and v2.7. Standard segments and datatypes are available as typed Python classes.
Yes. Zato handles both HL7v2 and FHIR natively, so you can parse v2 messages and build FHIR resources with IG-specific extensions in the same service. Typed Python classes are available for both protocols, including extensions from US Core, UK Core, Da Vinci, and other Implementation Guides.
Complete list of fields in the IAR segment, HL7 v2.9.
| # | Python name | Datatype | Usage | Repeatable | Table |
|---|---|---|---|---|---|
| 1 | allergy_reaction_code | CWE | Required | No | - |
| 2 | allergy_severity_code | CWE | Required | No | HL70128 |
| 3 | sensitivity_to_causative_agent_code | CWE | Optional | No | HL70436 |
| 4 | management | ST | Optional | No | - |
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