2026 ICD-10-CM Diagnosis Code R56.00Simple febrile convulsions

ICD-10-CM Codes›R00–R99›R50-R69›R56

ICD-10-CM R56.00
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

R56.00 is a billable ICD-10-CM diagnosis code for simple febrile convulsions. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 100 through 101. As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established. Coders also document this condition as combined focal and generalized epilepsy. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Epilepsy; convulsions.

Code Identity

ICD-10-CM Code
R56.00
Billable Status
Yes — Valid for Submission
Code Describes
Simple febrile convulsions
Short Description
Simple febrile convulsions
Same as the full description in the CMS dataset.
Parent Code
R56.0
Febrile convulsions

Code Classification

ChapterR00–R99Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
SectionR50-R69General symptoms and signs
CategoryR56Convulsions, not elsewhere classified
This CodeR56.00Simple febrile convulsions

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Combined focal and generalized epilepsy
  • Familial febrile convulsions
  • Febrile convulsion
  • Genetic epilepsy with febrile seizures plus
  • Recurrent febrile convulsion
  • Simple febrile seizure

Tabular List NotesGuidance

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

Inclusion Terms

  • Febrile convulsion NOS
  • Febrile seizure 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.

    • Convulsions(idiopathic)
      • febrile
    • Convulsions(idiopathic)
      • febrile
        • simple
    • Seizure(s)
      • febrile (simple)

Clinical ClassificationClinical

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

CCSR NVS009
Epilepsy; convulsions
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Seizures

Seizures are symptoms of a brain problem. They happen because of sudden, abnormal electrical activity in the brain. When people think of seizures, they often think of convulsions in which a person's body shakes rapidly and uncontrollably. Not all seizures cause convulsions. There are many types of seizures and some have mild symptoms.

Read the full article at MedlinePlus

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

Convert R56.00 to ICD-9-CMHistory

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

ICD-9-CM
780.31 Febrile convulsions NOS
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 R56.00Overview

Is R56.00 (Febrile convulsions) a billable code?

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

What MS-DRG does R56.00 group to?

When simple febrile convulsions is the principal diagnosis on an inpatient stay, it groups to MS-DRG 100, 101, with relative weights from 0.9026 to 1.9368 depending on complications. Higher weights mean higher Medicare reimbursement.

Can R56.00 be a principal diagnosis?

Use it with care. This is a symptom code, so once a definitive diagnosis explaining the simple febrile convulsions is established, that condition takes the principal position instead.

What is the ICD-9 equivalent of R56.00?

Under the General Equivalence Mappings, simple febrile convulsions converts to ICD-9-CM 780.31 (febrile convulsions NOS). The mapping is a direct match.

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.