2026 ICD-10-CM Diagnosis Code B85.4Mixed pediculosis and phthiriasis
ICD-10-CM Codes›A00–B99›B85-B89›B85
- Billable — Valid for Submission
- Not Chronic
B85.4 is a billable ICD-10-CM diagnosis code for mixed pediculosis and phthiriasis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 606 through 607. Coders also document this condition as infestation by Pediculus. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Parasitic, other specified and unspecified infections.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Infestation by Pediculus
- Infestation by Phthirus
- Mixed pediculus infestation
- Pediculosis and phthirus infections
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
Index to Diseases and InjuriesGuidance
External Cause of Injuries IndexGuidance
References for this code in the External Cause of Injuries Index.
- Infestation
- Pediculus
- mixed (classifiable to more than one of the titles B85.0-B85.3)
- Lice(infestation)
- mixed (classifiable to more than one of the titles B85.0-B85.3)
- Pediculosis(infestation)
- mixed (classifiable to more than one of the titles B85.0-B85.3)
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Head Lice
Head lice are tiny insects that live on people's heads. Adult lice are about the size of sesame seeds. The eggs, called nits, are even smaller - about the size of a dandruff flake. Lice and nits are found on or near the scalp, most often at the neckline and behind the ears.
The full article covers:
- What are head lice?
- How do head lice spread?
- Who is at risk for head lice?
- What are the symptoms of head lice?
- How do you know if you have head lice?
- What are the treatments for head lice?
- Can head lice be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert B85.4 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About B85.4Overview
Is B85.4 (Pediculosis and phthiriasis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report mixed pediculosis and phthiriasis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does B85.4 group to?
When mixed pediculosis and phthiriasis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 606, 607, with relative weights from 0.9064 to 1.5132 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of B85.4?
Under the General Equivalence Mappings, mixed pediculosis and phthiriasis converts to ICD-9-CM 132.3 (mixed pedicul & phthirus). 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.
