2027 ICD-10-CM Diagnosis Code L50.1Idiopathic urticaria

ICD-10-CM Codes›L00–L99›L49-L54›L50

ICD-10-CM L50.1
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

L50.1 is a billable ICD-10-CM diagnosis code for idiopathic urticaria. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 606 through 607. Coders also document this condition as acute idiopathic urticaria. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Allergic reactions and Other specified inflammatory condition of skin.

Code Identity

ICD-10-CM Code
L50.1
Billable Status
Yes — Valid for Submission
Code Describes
Idiopathic urticaria
Short Description
Idiopathic urticaria
Same as the full description in the CMS dataset.
Parent Code
L50
Urticaria

Code Classification

ChapterL00–L99Diseases of the skin and subcutaneous tissue
SectionL49-L54Urticaria and erythema
CategoryL50Urticaria
This CodeL50.1Idiopathic urticaria

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute idiopathic urticaria
  • Acute urticaria
  • Idiopathic urticaria
  • Idiopathic urticaria and/or angioedema

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to L50.1: its own notes plus those printed at L50, block L49-L54, and Chapter 12. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From L50 Urticaria applies to 9 codes
  • allergic contact dermatitis (L23.-)
  • angioneurotic edema (T78.3)
  • giant urticaria (T78.3)
  • hereditary angio-edema (D84.1)
  • Quincke's edema (T78.3)
  • serum urticaria (T80.6-)
  • solar urticaria (L56.3)
  • urticaria neonatorum (P83.8)
  • urticaria papulosa (L28.2)
  • urticaria pigmentosa (D47.01)
From Block L49-L54 Urticaria and erythema applies to 33 codes

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 12 (L00-L99) Diseases of the skin and subcutaneous tissue applies to 1,001 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • lipomelanotic reticulosis (I89.8)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
  • systemic connective tissue disorders (M30-M36)
  • viral warts (B07.-)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name L50.1, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming L50.1: they are not reported together with it, unless the two conditions are unrelated.

  • L95 Vasculitis limited to skin, not elsewhere classified
    urticaria (L50.-) names L50.-, which includes this code
  • T78.3 Angioneurotic edema
    urticaria (L50.-) names L50.-, which includes this code

Excludes2 1

These codes carry an Excludes2 note naming L50.1: its condition is not part of those codes, and both may be reported when the patient has both.

  • L27 Dermatitis due to substances taken internally
    urticaria (L50.-) names L50.-, which includes this code

Code First 1

These codes say to code first a condition named in the note, and L50.1 is one of the conditions named.

  • F54 Psychological and behavioral factors associated with disorders or diseases classified elsewhere
    urticaria (L50.-) names L50.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INJ031
Allergic reactions
Default principal diagnosis: inpatient No · outpatient No
CCSR SKN002
Other specified inflammatory condition of skin
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Urticaria

    a vascular reaction of the skin characterized by erythema and wheal formation due to localized increase of vascular permeability. the causative mechanism may be allergy, infection, or stress.

Patient EducationClinical

Hives

Hives are red and sometimes itchy bumps on your skin. An allergic reaction to a drug or food usually causes them. Allergic reactions cause your body to release chemicals that can make your skin swell up in hives. People who have other allergies are more likely to get hives than other people. Other causes include infections and stress.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert L50.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
708.1 Idiopathic urticaria
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About L50.1Overview

What is the ICD-10 code for idiopathic urticaria?

The ICD-10-CM code for idiopathic urticaria is L50.1 (sometimes written as L501). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is L50.1 (Urticaria) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report idiopathic urticaria on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does L50.1 group to?

When idiopathic urticaria is the principal diagnosis on an inpatient stay, it groups to MS-DRG 607, 606, with relative weights from 0.8772 to 1.5721 depending on complications. Higher weights mean higher Medicare reimbursement.

Can L50.1 be reported with a code from L23?

Not as a rule. The Excludes1 note at L50, which applies to L50.1, lists "allergic contact dermatitis (L23.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

What is the ICD-9 equivalent of L50.1?

Under the General Equivalence Mappings, idiopathic urticaria converts to ICD-9-CM 708.1 (idiopathic urticaria). The mapping is a direct match.