2027 ICD-10-CM Diagnosis Code L51.9Erythema multiforme, unspecified

ICD-10-CM Codes›L00–L99›L49-L54›L51

ICD-10-CM L51.9
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

L51.9 is a billable ICD-10-CM diagnosis code for erythema multiforme, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 595 through 596. 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
L51.9
Billable Status
Yes — Valid for Submission
Code Describes
Erythema multiforme, unspecified
Short Description
Erythema multiforme, unspecified
Same as the full description in the CMS dataset.
Parent Code
L51
Erythema multiforme

Code Classification

ChapterL00–L99Diseases of the skin and subcutaneous tissue
SectionL49-L54Urticaria and erythema
CategoryL51Erythema multiforme
This CodeL51.9Erythema multiforme, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Coccidioidomycosis with erythema multiforme
  • Drug-induced erythema multiforme
  • EMPACT syndrome
  • Erythema multiforme
  • Erythema multiforme co-occurrent with ulcer of oral mucous membrane
  • Erythema multiforme due to bacterial infection
  • Erythema multiforme due to Herpes simplex infection
  • Erythema multiforme due to malignancy
  • Erythema multiforme due to Mycoplasma pneumoniae infection
  • Erythema multiforme due to systemic fungal infection
  • Erythema multiforme due to viral disease
  • Erythema multiforme major
  • Erythema multiforme minor
  • Erythema multiforme of pregnancy
  • Erythema multiforme, dermal type
  • Gingival disease due to erythema multiforme
  • Herpes iris
  • Lip ulcer
  • Mucous membrane erythema
  • Pregnancy eruption
  • Ulcer of lips due to erythema multiforme

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to L51.9: its own notes plus those printed at L51, block L49-L54, and Chapter 12. A note printed at a category, block or chapter applies to every code under it.

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Erythema iris
  • Erythema multiforme major NOS
  • Erythema multiforme minor NOS
  • Herpes iris

Excludes1

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

From L51 Erythema multiforme applies to 6 codes
  • staphylococcal scalded skin syndrome (L00)
  • Ritter's disease (L00)
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.-)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From L51 Erythema multiforme applies to 6 codes
  • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • code to identify associated manifestations, such as:
  • arthropathy associated with dermatological disorders (M14.8-)
  • conjunctival edema (H11.42)
  • conjunctivitis (H10.22-)
  • corneal scars and opacities (H17.-)
  • corneal ulcer (H16.0-)
  • edema of eyelid (H02.84-)
  • inflammation of eyelid (H01.8-)
  • keratoconjunctivitis sicca (H16.22-)
  • mechanical lagophthalmos (H02.22-)
  • stomatitis (K12.-)
  • symblepharon (H11.23-)
  • code to identify percentage of skin exfoliation (L49.-)

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

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name L51.9, its category, or a range that includes it.

Code First 1

These codes say to code first a condition named in the note, and L51.9 is one of the conditions named.

  • M14.8 Arthropathies in other specified diseases classified elsewhere
    erythema multiforme (L51.-) names L51.-, 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

  • Erythema Multiforme

    a skin and mucous membrane disease characterized by an eruption of macules, papules, nodules, vesicles, and/or bullae with characteristic bull's-eye lesions usually occurring on the dorsal aspect of the hands and forearms.

Patient EducationClinical

Skin Conditions

Your skin is your body's largest organ. It covers the entire outside of your body. There are many ways that your skin protects your body and helps keep you healthy. For example, it:

The full article covers:

  • What does your skin do?
  • What problems and conditions can affect your skin?
  • How can I keep my skin healthy?

Read the full article at MedlinePlus

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

Convert L51.9 to ICD-9-CMHistory

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

ICD-9-CM
695.10 Erythema multiforme NOS
Approximate The match is approximate rather than exact.

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 L51.9Overview

What is the ICD-10 code for erythema multiforme, unspecified?

The ICD-10-CM code for erythema multiforme, unspecified is L51.9 (sometimes written as L519). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is L51.9 (Erythema multiforme) a billable code?

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

What MS-DRG does L51.9 group to?

When erythema multiforme, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 596, 595, with relative weights from 1.1067 to 2.0230 depending on complications. Higher weights mean higher Medicare reimbursement.

Can L51.9 be reported with L00?

Not as a rule. The Excludes1 note at L51, which applies to L51.9, lists "staphylococcal scalded skin syndrome (L00)". 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).

Does L51.9 need an additional code?

When the condition applies, yes. The Use Additional Code note at L51, which applies to L51.9, reads: code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5); code to identify associated manifestations, such as:; arthropathy associated with dermatological disorders (M14.8-); conjunctival edema (H11.42); conjunctivitis (H10.22-); and 9 more listed in the Instructional Notes section. The additional code is reported after L51.9.