AL1 — Allergy Information
Follows PID in ADT messages. Also appears in ORM (orders) when allergy information is relevant to order processing.
The AL1 segment carries patient allergy information including allergen type, allergen identity, severity, and documented reactions. Multiple AL1 segments can be included in a message for patients with multiple allergies.
Real-World Context
AL1 drives medication safety systems. Allergen codes and severity in AL1.3 and AL1.4 must be in the format the pharmacy system expects or drug-allergy checking fails silently. The most dangerous production scenario is when an allergen is transmitted but the code is not in the pharmacy system formulary — the allergy check simply does not fire. Always validate allergen codes against the receiving system code table.
Field Reference
Click any row to see the full description, common values, and troubleshooting tip.
| # | Field Name | Type | Req | Max Len | |
|---|---|---|---|---|---|
| 1 | Set ID - AL1 | SI | R | 4 | ▶ |
| 2 | Allergen Type Code | CE | O | 250 | ▶ |
| 3 | Allergen Code/Mnemonic/Description | CE | R | 250 | ▶ |
| 4 | Allergy Severity Code | CE | O | 250 | ▶ |
| 5 | Allergy Reaction Code | ST | O | 15 | ▶ |
| 6 | Identification Date | DT | O | 8 | ▶ |
Example Segment
1AL1||1|DA^Drug Allergy^HL70127|7980^Penicillin^NDC|SV^Severe^HL70128|ANAPHYLAXIS|20200315
Related Segments
Used In Message Types
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