2026 ICD-10-CM Diagnosis Code J35.01Chronic tonsillitis

ICD-10-CM Codes›J00–J99›J30-J39›J35

ICD-10-CM J35.01
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

J35.01 is a billable ICD-10-CM diagnosis code for chronic tonsillitis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 152 through 153. Coders also document this condition as caseous tonsillitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acute and chronic tonsillitis.

Code Identity

ICD-10-CM Code
J35.01
Billable Status
Yes — Valid for Submission
Code Describes
Chronic tonsillitis
Short Description
Chronic tonsillitis
Same as the full description in the CMS dataset.
Parent Code
J35.0
Chronic tonsillitis and adenoiditis

Code Classification

ChapterJ00–J99Diseases of the respiratory system
SectionJ30-J39Other diseases of upper respiratory tract
CategoryJ35Chronic diseases of tonsils and adenoids
This CodeJ35.01Chronic tonsillitis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Caseous tonsillitis
  • Chronic disease of tonsil
  • Chronic disease of tonsils AND/OR adenoids
  • Chronic tonsillitis

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.

    • Infection, infected, infective(opportunistic)
      • focal
        • tonsils
    • Remnant
      • tonsil
        • infected (chronic)
    • Septic
      • tonsils, chronic
    • Tonsillitis(acute) (catarrhal) (croupous) (follicular) (gangrenous) (infective) (lacunar) (lingual) (malignant) (membranous) (parenchymatous) (phlegmonous) (pseudomembranous) (purulent) (septic) (subacute) (suppurative) (toxic) (ulcerative) (vesicular) (viral)
      • chronic
    • Tonsillitis(acute) (catarrhal) (croupous) (follicular) (gangrenous) (infective) (lacunar) (lingual) (malignant) (membranous) (parenchymatous) (phlegmonous) (pseudomembranous) (purulent) (septic) (subacute) (suppurative) (toxic) (ulcerative) (vesicular) (viral)
      • hypertrophic

Clinical ClassificationClinical

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

CCSR RSP004
Acute and chronic tonsillitis
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Tonsillitis

Tonsils are lumps of tissue at the back of the throat. There are two of them, one on each side. Along with the adenoids, tonsils are part of the lymphatic system. The lymphatic system clears away infection and keeps body fluids in balance. Tonsils and adenoids work by trapping the germs coming in through the mouth and nose.

The full article covers:

  • What are tonsils?
  • What is tonsillitis?
  • What causes tonsillitis?
  • Who is at risk for tonsillitis?
  • Is tonsillitis contagious?
  • What are the symptoms of tonsillitis?
  • When does my child need to see a health care provider for tonsillitis?
  • How is tonsillitis diagnosed?

Read the full article at MedlinePlus

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

Convert J35.01 to ICD-9-CMHistory

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

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

Questions About J35.01Overview

Is J35.01 (Chronic tonsillitis and adenoiditis) a billable code?

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

What MS-DRG does J35.01 group to?

When chronic tonsillitis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 152, 153, with relative weights from 0.7382 to 1.1822 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of J35.01?

Under the General Equivalence Mappings, chronic tonsillitis converts to ICD-9-CM 474.00 (chronic tonsillitis). The mapping is a direct match.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.