2026 ICD-10-CM Diagnosis Code B34.9Viral infection, unspecified

ICD-10-CM Codes›A00–B99›B25-B34›B34

ICD-10-CM B34.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

B34.9 is a billable ICD-10-CM diagnosis code for viral infection, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 865 through 866. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Viral infection.

Code Identity

ICD-10-CM Code
B34.9
Billable Status
Yes — Valid for Submission
Code Describes
Viral infection, unspecified
Short Description
Viral infection, unspecified
Same as the full description in the CMS dataset.
Parent Code
B34
Viral infection of unspecified site

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB25-B34Other viral diseases
CategoryB34Viral infection of unspecified site
This CodeB34.9Viral infection, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute infectious tubulointerstitial nephritis
  • Acute infective otitis externa
  • Acute pyelonephritis
  • Acute tubulointerstitial nephritis
  • Acute viral disease
  • Acute viral otitis externa
  • Acute viral tubulointerstitial nephritis
  • Alanine aminotransferase level within reference range
  • Alanine aminotransferase within reference range with persistent viremia by polymerase chain reaction
  • Amantadine resistant virus present
  • Arthropathy associated with viral disease
  • Asymptomatic viremia
  • Autoimmune lymphoproliferative syndrome with recurrent viral infection
  • Bilateral infective arthritis of hands
  • Bilateral infective arthritis of knees
  • Bilateral infective arthritis of wrist regions
  • Bilateral viral arthritis of ankle joints
  • Bilateral viral arthritis of joint of hands
  • Bilateral viral arthritis of knee joints
  • Bilateral viral arthritis of shoulder region joints
  • Bilateral viral arthritis of wrist joints
  • Chronic viral otitis externa
  • Gingival disease caused by virus
  • Illness
  • Inconclusive evaluation finding
  • Infection caused by antimicrobial resistant virus
  • Infection involving inner ear
  • Infectious panuveitis
  • Infective arthritis of joint of bilateral shoulder regions
  • Infective arthritis of joint of left shoulder region
  • Infective arthritis of joint of right shoulder region
  • Infective arthritis of left ankle
  • Infective arthritis of left hand
  • Infective arthritis of left wrist
  • Infective arthritis of right ankle
  • Infective arthritis of right hand
  • Infective arthritis of right wrist
  • Influenza-like illness
  • Invasive viral infectious disease
  • Labyrinthitis of bilateral inner ears
  • Labyrinthitis of left inner ear
  • Labyrinthitis of right inner ear
  • Liver enzymes within reference range
  • Maternal postpartum viral disease
  • Neonatal dacryocystitis or conjunctivitis caused by virus
  • Neonatal hyperbilirubinemia due to viral infection
  • Neonatal viral infection of skin
  • Oseltamivir resistant virus present
  • Panuveitis caused by virus
  • Polyarticular viral arthritis
  • Recurrent viral infection
  • Sepsis caused by virus
  • Sustained viral response
  • Viral arthritis co-occurrent with hepatitis
  • Viral arthritis of hand
  • Viral arthritis of joint of left ankle
  • Viral arthritis of joint of left hand
  • Viral arthritis of joint of left knee
  • Viral arthritis of joint of right ankle
  • Viral arthritis of joint of right hand
  • Viral arthritis of joint of right knee
  • Viral arthritis of knee
  • Viral cardiovascular infection
  • Viral corneal ulcer
  • Viral disease
  • Viral disease in mother complicating childbirth
  • Viral ear infection
  • Viral esophagitis
  • Viral eye infection
  • Viral fever
  • Viral gastritis
  • Viral headache
  • Viral infection of peripheral nerve
  • Viral kidney infection
  • Viral labyrinthitis
  • Viral labyrinthitis of bilateral inner ears
  • Viral labyrinthitis of left inner ear
  • Viral labyrinthitis of right inner ear
  • Viral lower respiratory infection
  • Viral musculoskeletal infection
  • Viral myalgia
  • Viral myositis
  • Viral pharyngitis
  • Viral pleurisy
  • Viral posterior uveitis
  • Viral sinusitis
  • Viral syndrome
  • Viremia
  • Virus inconclusive
  • Virus present
  • Virus-associated atypical lymphoproliferative disorder
  • Zanamivir resistant virus present

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Viremia NOS

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Arthritis, arthritic(acute) (chronic) (nonpyogenic) (subacute)
      • in (due to)
        • viral disease NEC
    • Disease, diseased
      • nonarthropod-borne NOS (viral)
    • Disease, diseased
      • viral, virus
    • Disease, diseased
      • viral, virus
        • nonarthropod-borne NOS
    • Infection, infected, infective(opportunistic)
      • virus, viral NOS
    • Infection, infected, infective(opportunistic)
      • virus, viral NOS
        • unspecified nature or site
    • Otitis(acute)
      • externa
        • in (due to)
          • viral disease NEC
    • Syndrome
      • virus
    • Viremia

Clinical ClassificationClinical

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

CCSR INF008
Viral infection
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Viremia

    the presence of viruses in the blood.

  • Viral Esophagitis

    viral infection of the esophagus. it often occurs in immunocompromised patients and it is caused by cytomegalovirus or herpes simplex virus. symptoms include pain on swallowing, fever, and retrosternal burning.

  • Adenovirus DNA Viremia|AdV DNA Viremia

    a laboratory test result indicating the presence of adenovirus dna in the blood.

  • Grade 2 Viremia, CTCAE|Grade 2 Viremia

    moderate symptoms; medical intervention indicated

  • Grade 3 Viremia, CTCAE|Grade 3 Viremia

    severe or medically significant but not immediately life-threatening; hospitalization or prolongation of existing hospitalization indicated

  • Viremia

    a laboratory test result indicating the presence of a virus in the blood.

  • Viremia, CTCAE|Viremia

    a disorder characterized by the presence of a virus in the blood stream.

  • Cytomegaloviral Gastritis|CMV Gastritis|CMV-Related Gastritis|Cytomegalovirus Gastritis|Cytomegalovirus-Related Gastritis

    inflammation of stomach that is associated with cytomegalovirus.

  • Viral Gastritis

    inflammation of the stomach resulting from viral infection.

  • Acute Pyelonephritis

    sudden onset pyelonephritis.

Patient EducationClinical

Viral Infections

Viruses are very tiny germs. They are made of genetic material (either DNA or RNA) inside of a protein coating. There are a huge number of viruses on earth. Only a small number of them can infect humans. Those viruses can infect our cells, which may cause disease.

The full article covers:

  • What are viruses?
  • How are viruses spread?
  • How do viruses cause disease?
  • What are the treatments for viral infections?
  • Can viral infections be prevented?

Read the full article at MedlinePlus

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

Convert B34.9 to ICD-9-CMHistory

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

ICD-9-CM
790.8 Viremia 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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About B34.9Overview

Is B34.9 (Viral infection of unspecified site) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report viral infection, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does B34.9 group to?

When viral infection, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 865, 866, with relative weights from 0.8696 to 1.4983 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of B34.9?

Under the General Equivalence Mappings, viral infection, unspecified converts to ICD-9-CM 790.8 (viremia NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.