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Allergy ICD-10 Coding Guide for 2027 (FY2027 Codes for Allergy and Immunology Practices)
2026-10-02 · 8 min read
The short answer: the FY2027 ICD-10-CM code set took effect on October 1,
2026, and none of the allergy codes in this guide changed. We compared the
official CMS FY2026 and FY2027 code files code by code. What still trips
practices up is specificity: the allergen behind the rhinitis, the asthma
severity and whether it's an exacerbation, the food behind the allergy (and,
for milk and egg, whether the patient tolerates baked forms), and the
encounter type.
Every code below is quoted from the CMS FY2027 code descriptions file.
It's a documentation aid, not billing advice. Your coder, the official
coding guidelines and your payers' policies come first.
Allergic rhinitis (J30)
| Code | FY2027 title |
|---|---|
| J30.1 | Allergic rhinitis due to pollen |
| J30.2 | Other seasonal allergic rhinitis |
| J30.5 | Allergic rhinitis due to food |
| J30.81 | Allergic rhinitis due to animal (cat) (dog) hair and dander |
| J30.89 | Other allergic rhinitis |
| J30.9 | Allergic rhinitis, unspecified |
| J30.0 | Vasomotor rhinitis |
What the note needs: the trigger. Once skin testing shows pollen or dander
sensitivity that fits the history, the note can support J30.1 or J30.81
rather than J30.9. Practices often record more than one J30 code when a
patient has both seasonal and perennial triggers. Vasomotor rhinitis (J30.0)
is non-allergic, so a negative workup belongs in the note.
Asthma (J45) and eosinophilic asthma (J82.83)
Persistent asthma is coded by severity, and each severity level has three
fifth characters: 0 for uncomplicated, 1 for an acute exacerbation and 2 for
status asthmaticus.
| Code | FY2027 title |
|---|---|
| J45.20 / .21 / .22 | Mild intermittent asthma |
| J45.30 / .31 / .32 | Mild persistent asthma |
| J45.40 / .41 / .42 | Moderate persistent asthma |
| J45.50 / .51 / .52 | Severe persistent asthma |
| J45.909 | Unspecified asthma, uncomplicated |
| J45.990 | Exercise induced bronchospasm |
| J45.991 | Cough variant asthma |
| J82.83 | Eosinophilic asthma |
What the note needs: a stated severity and whether the patient is
exacerbating today. "Asthma, stable" leads to J45.909. "Moderate persistent
asthma, well controlled on current therapy" supports J45.40. Eosinophilic
asthma has its own code (J82.83), so if the workup supports it, say so in
the assessment.
Food allergy: status codes (Z91.01-) and reactions (T78)
Food allergy codes come in two families. The Z91.01- codes record that a
patient has a food allergy. The T78 codes describe a reaction and take a
seventh character for the encounter (A initial, D subsequent, S sequela).
| Code | FY2027 title |
|---|---|
| Z91.010 | Allergy to peanuts |
| Z91.0110 / .0111 / .0112 | Allergy to milk products, unspecified / with tolerance to baked milk / with reactivity to baked milk |
| Z91.0120 / .0121 / .0122 | Allergy to eggs, unspecified / with tolerance to baked egg / with reactivity to baked egg |
| Z91.013 | Allergy to seafood |
| Z91.014 | Allergy to mammalian meats |
| Z91.018 | Allergy to other foods |
| Z91.02 | Food additives allergy status |
| T78.01XA | Anaphylactic reaction due to peanuts, initial encounter |
| T78.05XA | Anaphylactic reaction due to tree nuts and seeds, initial encounter |
| T78.070A / T78.071A | Anaphylactic reaction due to milk and dairy products with tolerance / with reactivity to baked milk, initial encounter |
| T78.080A / T78.081A | Anaphylactic reaction due to egg with tolerance / with reactivity to baked egg, initial encounter |
| T78.19XA | Other adverse food reactions, not elsewhere classified, initial encounter |
What the note needs: the specific food, and for milk and egg, the
baked-food result. If a baked milk or baked egg challenge was done, or the
history clearly shows the patient eats baked goods without reacting, write
that down. Without it, the record can only support the "unspecified" code.
Mammalian meat allergy has its own status code (Z91.014).
Urticaria and angioedema (L50, T78.3, D84.1)
| Code | FY2027 title |
|---|---|
| L50.0 | Allergic urticaria |
| L50.1 | Idiopathic urticaria |
| L50.2 | Urticaria due to cold and heat |
| L50.3 | Dermatographic urticaria |
| L50.5 | Cholinergic urticaria |
| L50.6 | Contact urticaria |
| L50.9 | Urticaria, unspecified |
| T78.3XXA | Angioneurotic edema, initial encounter |
| D84.1 | Defects in the complement system |
What the note needs: an identified trigger (L50.0) or a documented lack of
one (L50.1), and the physical trigger where there is one. Dermatographism seen
on exam is also worth recording because it affects skin-test
interpretation. For hereditary angioedema, practices use D84.1, the
complement-defect code.
Anaphylaxis and drug allergy (T78.2, T88.6, Z87.892, Z88)
| Code | FY2027 title |
|---|---|
| T78.2XXA | Anaphylactic shock, unspecified, initial encounter |
| T88.6XXA | Anaphylactic reaction due to adverse effect of correct drug or medicament properly administered, initial encounter |
| Z87.892 | Personal history of anaphylaxis |
| Z88.0 | Allergy status to penicillin |
| Z88.1 | Allergy status to other antibiotic agents |
| Z88.2 | Allergy status to sulfonamides |
| Z88.8 | Allergy status to other drugs, medicaments and biological substances |
What the note needs: at a penicillin-allergy evaluation, the reported
reaction, its timing and what the evaluation showed. If the label is removed,
the note should say so plainly so the allergy list can be updated.
Insect venom (T63.4, Z91.03)
| Code | FY2027 title |
|---|---|
| T63.441A | Toxic effect of venom of bees, accidental (unintentional), initial encounter |
| T63.451A | Toxic effect of venom of hornets, accidental (unintentional), initial encounter |
| T63.461A | Toxic effect of venom of wasps, accidental (unintentional), initial encounter |
| T63.421A | Toxic effect of venom of ants, accidental (unintentional), initial encounter |
| Z91.030 | Bee allergy status |
| Z91.038 | Other insect allergy status |
What the note needs: the insect, if it's known. Bee, hornet, wasp and ant
each have their own code.
Skin: atopic and contact dermatitis (L20, L23)
| Code | FY2027 title |
|---|---|
| L20.84 | Intrinsic (allergic) eczema |
| L20.89 | Other atopic dermatitis |
| L20.9 | Atopic dermatitis, unspecified |
| L23.0 | Allergic contact dermatitis due to metals |
| L23.1 | Allergic contact dermatitis due to adhesives |
| L23.2 | Allergic contact dermatitis due to cosmetics |
| L23.5 | Allergic contact dermatitis due to other chemical products |
| L23.7 | Allergic contact dermatitis due to plants, except food |
| L23.9 | Allergic contact dermatitis, unspecified cause |
What the note needs: for patch testing, the relevant positive allergens
and the clinician's judgement of relevance. A nickel positive that matches
the history supports L23.0. "Contact dermatitis" with no cause leaves you at
L23.9.
Other codes allergy practices use
| Code | FY2027 title |
|---|---|
| Z01.82 | Encounter for allergy testing |
| Z51.6 | Encounter for desensitization to allergens |
| K20.0 | Eosinophilic esophagitis |
| J32.9 / J33.9 | Chronic sinusitis, unspecified / Nasal polyp, unspecified |
| H10.13 | Acute atopic conjunctivitis, bilateral |
| H10.45 | Other chronic allergic conjunctivitis |
| R05.3 | Chronic cough |
Where the codes come from
A code is only as specific as the note behind it. Most of the specificity
above comes out of the visit itself. The parent says the child eats muffins
with egg. The patient says the hives come with cold water. The asthma was
fine until last week. Those details often don't make it into a note written
at 8 PM.
Medora was built with a working allergy practice to keep those details:
- Medora Copilot listens to the allergy visit and drafts an allergy-structured
SOAP note (HPI, ROS, assessment and plan, workup) with pertinent negatives.
- It suggests ICD-10 codes from the note. The clinician reviews them, edits
and signs every note, and nothing is filed without the clinician.
- Evidence Mapping links each line of the note back to the part of the visit
conversation it came from, so the clinician can check where a detail like
"tolerates baked egg" came from before signing.
- Skin-test results the nurse confirmed sit alongside the drafted note, so
the testing that supports a J30 code is in front of the clinician at
sign-off.
In a 60-day pilot at Allergy Affiliates, provider sign-off per skin-test visit went from 18 minutes to 4
Frequently asked questions
Did any allergy ICD-10 codes change on October 1, 2026?
Not among the codes in this guide. The FY2027 ICD-10-CM update took effect
on October 1, 2026, and the J30, J45, J82.83, L20, L23, L50, T63.4, T78,
T88.6, Z88 and Z91.0 codes in this guide have the same titles in the FY2027
and FY2026 CMS code files.
What is the ICD-10 code for allergic rhinitis due to pollen?
J30.1, "Allergic rhinitis due to pollen." Use J30.81 for cat or dog dander,
J30.2 for other seasonal allergic rhinitis, J30.89 for other allergic
rhinitis, and J30.9 when the cause isn't documented.
Is there an ICD-10 code for egg allergy with baked egg tolerance?
Yes. Z91.0121 is "Allergy to eggs with tolerance to baked egg" and Z91.0122 is
"Allergy to eggs with reactivity to baked egg." Milk has the same structure:
Z91.0111 and Z91.0112. The T78.07- and T78.08- reaction codes split the same
way.
What ICD-10 code is used for an allergy testing visit?
Z01.82 is "Encounter for allergy testing." When testing finds a condition,
that diagnosis (for example J30.1) is usually documented alongside it. Check
your payers' policies for sequencing.
Does Medora choose the codes?
No. Medora Copilot suggests ICD-10 codes from the note. The clinician reviews
them and signs the note.
Try it on your own visits
- See how Medora handles allergy documentation
- Start the 14-day free trial of Medora Scribe (no card needed)
- Book a demo
- Read the full buyer's guide
- The skin test documentation checklist
*Source: CMS FY2027 ICD-10-CM code descriptions in tabular order
(cms.gov/files/zip/2027-code-descriptions-tabular-order.zip), compared with
the FY2026 file. Code titles are quoted from it. Confirm codes, sequencing and
payer rules with your coder before changing how you bill.*