Patient allergy information

AL1 carries patient allergy information - the type of allergen (drug, food, environmental), a description or code for the specific allergen, severity level, reaction details, and when the allergy was identified. It appears in ADT, ORM, and ORU messages.

Create an AL1 segment and read its fields directly:

from zato.hl7v2.v2_9 import AL1, CWE

al1 = AL1()
al1.set_id_al1 = '1'
al1.allergen_code_mnemonic_description = CWE(
    text='Pollen')
al1.allergy_severity_code = CWE(
    identifier='MI')
al1.allergy_reaction_code = 'Sneezing'

allergen = al1.allergen_code_mnemonic_description
severity = al1.allergy_severity_code
reaction = al1.allergy_reaction_code

Create separate AL1 instances, each with its own set_id_al1:

from zato.hl7v2.v2_9 import AL1, CWE

al1_drug = AL1()
al1_drug.set_id_al1 = '1'
al1_drug.allergen_type_code = CWE(
    identifier='DA')
al1_drug.allergen_code_mnemonic_description = CWE(
    text='Aspirin')

al1_env = AL1()
al1_env.set_id_al1 = '2'
al1_env.allergen_type_code = CWE(
    identifier='EA')
al1_env.allergen_code_mnemonic_description = CWE(
    text='Pollen')

The allergen_type_code field uses HL7 table 0127. Common values include:

from zato.hl7v2.v2_9 import AL1, CWE

al1 = AL1()

# DA = Drug allergy
al1.allergen_type_code = CWE(identifier='DA')

# FA = Food allergy
al1.allergen_type_code = CWE(identifier='FA')

# EA = Environmental allergy
al1.allergen_type_code = CWE(identifier='EA')

The allergy_severity_code field uses the CWE datatype with HL7 table 0128 codes:

from zato.hl7v2.v2_9 import AL1, CWE

al1 = AL1()

# MI = Mild
al1.allergy_severity_code = CWE(identifier='MI')

# MO = Moderate
al1.allergy_severity_code = CWE(identifier='MO')

# SV = Severe
al1.allergy_severity_code = CWE(identifier='SV')

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.