Find Allergists by Zip Code — NPI Registry Guide

Q: Why does querying 'Allergist' return zero results, and why is the ampersand required?

'Allergist' is a professional title — it is not a NUCC taxonomy code in the CMS NPI registry. The registry uses 'Allergy & Immunology' (207K00000X) as the official taxonomy description, and the ampersand is part of the exact string the API expects. Omitting the ampersand and querying 'Allergy Immunology' or 'Allergy and Immunology' returns zero results. The URL-encoded form is taxonomy_description=Allergy+%26+Immunology.

Q: Why does 'Immunology' alone return a different, smaller group of providers?

'Immunology' returns 34 records nationally — clinical immunologists and laboratory immunologists who work primarily in diagnostic or research settings, not in the outpatient allergy practice where biologics and immunotherapy products are prescribed. These are a different professional group from board-certified allergist-immunologists. 'Immunology' alone is not a substitute for 'Allergy & Immunology' when building an allergy territory call list.

Q: What is the Allergy & Immunology, Allergy sub-code (207KA0200X), and do those providers appear in a standard query?

207KA0200X is a NUCC sub-code for physicians who have the Allergy subspecialty within Allergy & Immunology. Memphis returned 2 providers with this as their primary taxonomy. Because the NPI API performs prefix matching, a query for 'Allergy & Immunology' will also return 'Allergy & Immunology, Allergy' records — so they are already included in your standard query without a separate pass.

Q: Does the Allergy & Immunology query include pediatric allergists, and is there a separate pediatric allergy taxonomy?

A query for 'Allergy & Immunology' (207K00000X) returns adult and pediatric allergist-immunologists together — both train through the same ABAI fellowship and share the same NUCC code. There is no separate 'Pediatric Allergy & Immunology' code that returns data — that string returned zero records on 2026-06-13. Pediatric allergy is not a distinct NUCC taxonomy in the CMS registry.

Q: What credential and entity-type mix does a Memphis allergy & immunology call list show?

Memphis returned 54 records (2026-06-13): 43 NPI-1 (207K00000X primary) · 3 NPI-1 with Allergy & Immunology sub-codes · 2 NPI-1 Allergy & Immunology, Allergy (207KA0200X) · 1 Otolaryngology (ENT overlap practice) · 1 Pediatrics subspecialty · 3 NPI-2 allergy practice organizations · 1 Nurse Practitioner. Filter enumeration_type=NPI-1 and check basic.credential for MD/DO to isolate the prescribing physician call list. The 43 primary 207K00000X records are the core allergist-immunologist pool.

Methodology: All counts queried live from CMS NPI Registry API v2.1 on 2026-06-13 using taxonomy_description=Allergy+%26+Immunology. No auth required. result_count=200 means page cap hit. Raw data: npi-counts-allergy-immunology.json · Memphis raw · Wyoming raw · Script: npi-counts-allergy-immunology.ps1

The short answer: Use taxonomy_description=Allergy+%26+Immunology (NUCC 207K00000X). The %26 is a URL-encoded ampersand — it is required. "Allergist" returns zero. "Immunology" alone returns 34 lab/clinical immunologists — a completely different group.

Critical gotcha — empirically verified 2026-06-13: taxonomy_description=Allergist returns 0 results. The more tempting shortcut — Immunology — returns 34 records nationally, but these are clinical/laboratory immunologists working in diagnostic and research settings, not the outpatient allergist-immunologists who prescribe biologics and administer immunotherapy. The Immunology string is not a substitute. The correct string is Allergy+%26+Immunology — the ampersand is part of the official NUCC taxonomy name and the API requires it exactly.

Allergy & immunology records by market

Queried 2026-06-13 using taxonomy_description=Allergy+%26+Immunology. This is a moderately sparse specialty — only New York hits the 200-record cap at city level.

Market	Records returned	Notes
New York, NY	200+	Capped — high density in the metro
Houston, TX	163	Complete count for city proper
Los Angeles, CA	148	Complete count
Chicago, IL	174	Complete count
Nashville, TN	51	Complete count
Phoenix, AZ	56	Complete count
Memphis, TN	54	Complete count — see drill-down below
Wyoming (statewide)	11	Among the sparsest states — query statewide
Vermont (statewide)	11	Equally sparse — 11 providers statewide

Memphis drill-down — Allergy & Immunology, 2026-06-13 (n=54)
Entity type: 49 NPI-1 (individual providers) · ~5 NPI-2 (allergy practice organizations)
Primary taxonomy breakdown:
• 43 records: 207K00000X — Allergy & Immunology (core physician pool)
• 3 records: 207RA0201X — Internal Medicine, Allergy & Immunology
• 2 records: 207KA0200X — Allergy & Immunology, Allergy (sub-code)
• 1 record: 207Y00000X — Otolaryngology (ENT-based allergy practice)
• 2 records: Pediatrics-related (Adolescent Medicine, Pediatric Allergy/Immunology sub-code)
• 1 record: Clinical Nurse Specialist, Adult Health
The 43 primary 207K00000X records are the core allergist-immunologist physician pool. Filter enumeration_type=NPI-1 and verify MD/DO credentials for a physician-only list.

Allergy taxonomy strings — the two-string comparison

How to build an allergy & immunology call list

String	NUCC code	National count	Who they are
`Allergy & Immunology`	207K00000X	200+ (capped)	Board-certified allergist-immunologists in outpatient practice — the call list you need
`Immunology`	207NI0002X	34	Clinical and laboratory immunologists in diagnostic/research settings — a different, small group
`Allergy & Immunology, Allergy`	207KA0200X	200+ (capped)	Allergy subspecialty sub-code — already included in Allergy & Immunology prefix query
`Pediatric Allergy/Immunology`	2080P0201X	0 results	String returned zero on 2026-06-13 — pediatric allergists use the general 207K00000X code
`Allergist`	N/A	0 results	Professional title — not a NUCC taxonomy code

Use the exact ampersand string

https://npiregistry.cms.hhs.gov/api/?version=2.1
  &taxonomy_description=Allergy+%26+Immunology
  &city=Memphis&state=TN&limit=200

The %26 encodes the ampersand in the URL. This returns 207K00000X (primary allergist-immunologists) and also prefix-matches sub-codes like 207KA0200X. No separate second pass needed for sub-codes.

Filter to physicians in your product's patient population

The raw Memphis data includes ENT physicians with allergy practices and Pediatrics subspecialty records. If your product is adult-only, inspect the basic.credential and primary taxonomy code fields to segment the list. Filter enumeration_type=NPI-1 to remove practice organization records.

Query statewide in rural markets

Wyoming and Vermont each have only 11 allergists statewide. There is no useful radius to apply — query by state, take the complete list, and plan accordingly. The entire call list for Wyoming is smaller than a single Memphis ZIP code radius.

Radius guidance for allergy & immunology territories

Allergy practices are outpatient-based — patients come for weekly immunotherapy injections, so allergists maintain accessible office locations. This makes the specialty more geographically distributed than hospital-anchored fields, but still sparse in rural areas.

Frequently asked questions

Why does querying "Allergist" return zero results, and why is the ampersand required?

"Allergist" is a professional title — it is not a NUCC taxonomy code. The registry uses "Allergy & Immunology" (207K00000X) as the official taxonomy description, and the ampersand is part of the exact string the API expects. Omitting the ampersand and querying "Allergy Immunology" or "Allergy and Immunology" returns zero results. The URL-encoded form is taxonomy_description=Allergy+%26+Immunology.

Why does "Immunology" alone return a different, smaller group of providers?

"Immunology" returns 34 records nationally — clinical immunologists and laboratory immunologists working primarily in diagnostic or research settings, not the outpatient allergy-immunotherapy practice where biologics are prescribed. These are a different professional group from board-certified allergist-immunologists. "Immunology" alone is not a substitute for "Allergy & Immunology" when building an allergy territory call list.

How sparse is allergy & immunology in rural states compared to other specialties?

Wyoming and Vermont each returned 11 allergist-immunologists statewide on 2026-06-13. This is among the smallest complete-state counts in the registry — comparable to rheumatology in sparse markets. Memphis city alone returned 54. A rep covering Wyoming should plan statewide coverage with extended visit intervals rather than metro-focused call planning.

What is the Allergy & Immunology, Allergy sub-code (207KA0200X), and do those providers appear in a standard query?

207KA0200X is a NUCC sub-code for physicians with the Allergy subspecialty within Allergy & Immunology. Memphis returned 2 providers with this as their primary taxonomy. Because the NPI API performs prefix matching, a query for "Allergy & Immunology" also returns "Allergy & Immunology, Allergy" records — so they are already included in your standard query without a separate pass.

Does the Allergy & Immunology query include pediatric allergists, and is there a separate pediatric allergy taxonomy?

The query returns both adult and pediatric allergist-immunologists together — both train through the same ABAI fellowship and share the 207K00000X code. There is no active "Pediatric Allergy & Immunology" code that returns data — that string returned zero records on 2026-06-13. Pediatric allergy is not a distinct active NUCC taxonomy.

What credential and entity-type mix does a Memphis allergy & immunology call list show?

Memphis returned 54 records (2026-06-13): 43 primary 207K00000X records · 3 Internal Medicine, Allergy & Immunology · 2 Allergy sub-code · 2 Pediatrics-related · 1 Otolaryngology · 1 Clinical Nurse Specialist · ~5 NPI-2 organizations. Filter enumeration_type=NPI-1 and verify MD/DO credentials for a physician-only list. The 43 primary 207K00000X records are the core allergist-immunologist physician pool.