2027 ICD-10-CM Diagnosis Code B85.3Phthiriasis

ICD-10-CM Codes›A00–B99›B85-B89›B85

ICD-10-CM B85.3
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

B85.3 is a billable ICD-10-CM diagnosis code for phthiriasis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 606 through 607. Coders also document this condition as dermatosis caused by lice. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Parasitic, other specified and unspecified infections.

Code Identity

ICD-10-CM Code
B85.3
Billable Status
Yes — Valid for Submission
Code Describes
Phthiriasis
Short Description
Phthiriasis
Same as the full description in the CMS dataset.
Parent Code
B85
Pediculosis and phthiriasis

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB85-B89Pediculosis, acariasis and other infestations
CategoryB85Pediculosis and phthiriasis
This CodeB85.3Phthiriasis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Dermatosis caused by lice
  • Disseminated phthiriasis
  • Infestation by Phthirus
  • Infestation by Phthirus pubis
  • Phthiriasis of eyelashes

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to B85.3: 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

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Infestation by crab-louse
  • Infestation by Phthirus pubis

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.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name B85.3, its category, or a range that includes it.

Applicable To 1

These notes mention B85.3.

  • B85.4 Mixed pediculosis and phthiriasis
    Infestation classifiable to more than one of the categories B85.0-B85.3 names B85.0-B85.3, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

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

CCSR INF009
Parasitic, other specified and unspecified infections
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Pediculosis Pubis

    infestation of the pubic hair by the pthirus pubis parasite which results in mild to intense itching and macular lesions. the parasite, also known as crab lice, is transmitted through skin to skin contact with an infected person or through direct contact with infested objects.

Patient EducationClinical

Parasitic Diseases

Parasites are living things that use other living things - like your body - for food and a place to live. You can get them from contaminated food or water, a bug bite, or sexual contact. Some parasitic diseases are easily treated and some are not.

Read the full article at MedlinePlus

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

Convert B85.3 to ICD-9-CMHistory

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

ICD-9-CM
132.2 Phthirus pubis
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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About B85.3Overview

What is the ICD-10 code for phthiriasis?

The ICD-10-CM code for phthiriasis is B85.3 (sometimes written as B853). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is B85.3 (Pediculosis and phthiriasis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report phthiriasis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does B85.3 group to?

When phthiriasis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 607, 606, with relative weights from 0.8772 to 1.5721 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of B85.3?

Under the General Equivalence Mappings, phthiriasis converts to ICD-9-CM 132.2 (phthirus pubis). The mapping is a direct match.