2027 ICD-10-CM Diagnosis Code A42Actinomycosis

ICD-10-CM Codes›A00–B99›A30-A49›A42

ICD-10-CM A42
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

A42 is a non-billable ICD-10-CM category code for actinomycosis, so it cannot be submitted on claims. Use a more specific code from this category instead, such as A42.0, A42.1, A42.2, and A42.7.

Code Identity

ICD-10-CM Code
A42
Billable Status
No — Non-Billable Category
Code Describes
Actinomycosis
Short Description
Actinomycosis
Same as the full description in the CMS dataset.
Chapter
A30-A49
Other bacterial diseases

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA30-A49Other bacterial diseases
CategoryA42Actinomycosis
This CodeA42Actinomycosis

Specific Coding for ActinomycosisOverview

Non-specific codes like A42 require more characters. Use one of these billable codes instead:

  • Use A42.0 for Pulmonary actinomycosis

  • Use A42.1 for Abdominal actinomycosis

  • Use A42.2 for Cervicofacial actinomycosis

  • Use A42.7 for Actinomycotic sepsis

  • A42.8 for Other forms of actinomycosis

  • Use A42.81 for Actinomycotic meningitis

  • Use A42.82 for Actinomycotic encephalitis

  • Use A42.89 for Other forms of actinomycosis

  • Use A42.9 for Actinomycosis, unspecified

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to A42: its own notes plus those printed at Chapter 1. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • diseases generally recognized as communicable or transmissible

Excludes1

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

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 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • carrier or suspected carrier of infectious disease (Z22.-)
  • certain localized infections - see body system-related chapters
  • infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
  • infectious and parasitic diseases specific to the perinatal period (P35-P39)
  • influenza and other acute respiratory infections (J00-J22)

Use Additional Code

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

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • code to identify resistance to antimicrobial drugs (Z16.-)

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

Clinical InformationClinical

  • Actinomycosis

    infections with bacteria of the genus actinomyces.

Patient EducationClinical

Bacterial Infections

Bacteria are tiny organisms (living things) that have only one cell. Under a microscope, they look like balls, rods, or spirals. They can be found almost everywhere on Earth. There are lots of bacteria in and on your body. In fact, your body has about 10 times more bacteria cells than human cells.

The full article covers:

  • What are bacteria?
  • How do bacterial infections spread?
  • What are the treatments for bacterial infections?
  • Can bacterial infections be prevented?

Read the full article at MedlinePlus

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

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 A42Overview

What is the ICD-10 code for actinomycosis?

A42 is the ICD-10-CM category for actinomycosis, but it is a non-billable header: claims need a more specific code from this category, listed on this page.

Is A42 (Actinomycosis) a billable code?

No. This is a category header that groups the codes for actinomycosis, and headers cannot be submitted on claims. Claims for actinomycosis need a more specific code from this category, such as A42.0, A42.1, and A42.2.

Can A42 be reported with B47.1?

Not as a rule. The Excludes1 note on A42 lists "actinomycetoma (B47.1)". 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).