2026 ICD-10-CM Diagnosis Code T49.4X5AAdverse effect of keratolytics, keratoplastics, and other hair treatment drugs and preparations, initial encounter

ICD-10-CM Codes›S00–T88›T36-T50›T49

ICD-10-CM T49.4X5A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T49.4X5A is a billable ICD-10-CM diagnosis code for adverse effect of keratolytics, keratoplastics, and other hair treatment drugs and preparations, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 917 through 918. The code is not accepted as a principal diagnosis by the Medicare Code Editor. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Adverse effects of drugs and medicaments, initial encounter.

Code Identity

ICD-10-CM Code
T49.4X5A
Billable Status
Yes — Valid for Submission
Code Describes
Adverse effect of keratolytics, keratoplastics, and other hair treatment drugs and preparations, initial encounter
Short Description
Adverse effect of keratolyt/keratplst/hair trmt drug, init
Parent Code
T49.4X5
Adverse effect of keratolytics, keratoplastics, and other hair treatment drugs and preparations

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT36-T50Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances
CategoryT49Poisoning by, adverse effect of and underdosing of topical agents primarily affecting skin and mucous membrane and by ophthalmological, otorhinorlaryngological and dental drugs
This CodeT49.4X5AAdverse effect of keratolytics, keratoplastics, and other hair treatment drugs and preparations, initial encounter

Code EditsBilling

Medicare Code Editor checks that affect claim validity for T49.4X5A.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Adverse reaction to dimethyl sulfoxide and/or idoxuridine
  • Adverse reaction to salicylate
  • Allergic reaction to hair dye
  • Contact dermatitis caused by keratolytic
  • Dithranol adverse reaction
  • Dithranol burn
  • Dithranol cream adverse reaction
  • Dithranol ointment adverse reaction
  • Dithranol paste adverse reaction
  • Hypothyroidism caused by drug
  • Hypothyroidism caused by resorcinol
  • Podophyllum resin adverse reaction
  • Topical salicylic acid adverse reaction

Coding GuidelinesGuidance

When coding an adverse effect of a drug that has been correctly prescribed and properly administered, assign the appropriate code for the nature of the adverse effect followed by the appropriate code for the adverse effect of the drug.

The appropriate 7th character is to be added to each code from block Poisoning by, adverse effect of and underdosing of topical agents primarily affecting skin and mucous membrane and by ophthalmological, otorhinorlaryngological and dental drugs (T49). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Clinical ClassificationClinical

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

CCSR INJ028
Adverse effects of drugs and medicaments, initial encounter
Default principal diagnosis: inpatient No · outpatient Yes

Clinical InformationClinical

  • Allantoin

    a urea hydantoin that is found in urine and plants and is used in dermatological preparations.

  • Anthralin

    an anthracene derivative that disrupts function and structure of mitochondria and is used for the treatment of dermatoses, especially psoriasis. it may cause folliculitis.

  • Capsaicin

    an alkylamide found in capsicum that acts at trpv cation channels.

  • Capsicum

    a plant genus of the family solanaceae. the hot peppers yield capsaicin, which activates vanilloid receptors. several varieties have sweet or pungent edible fruits that are used as vegetables when fresh and spices when the pods are dried.

  • Anacardic Acids

    a group of 6-alkyl salicylic acids that are found in anacardium and known for causing contact dermatitis.

  • Salicylates

    the salts or esters of salicylic acids, or salicylate esters of an organic acid. some of these have analgesic, antipyretic, and anti-inflammatory activities by inhibiting prostaglandin synthesis.

  • Salicylic Acid

    a compound obtained from the bark of the white willow and wintergreen leaves. it has bacteriostatic, fungicidal, and keratolytic actions.

Table of Drugs and ChemicalsClinical

Substances in the Table of Drugs and Chemicals that reference this code family. Always confirm in the Tabular List before coding.

SubstanceAccidentalSelf-harmAssaultUndeter­minedAdverse
Effect		Under­dosing
AllantoinT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Alum (medicinal)T49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Alum (medicinal)::nonmedicinal (ammonium) (potassium)T49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
AnthralinT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
AntiseborrheicsT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Bleaching agent (medicinal)T49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
ButantroneT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Cade oilT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
CapsicumT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Carbazochrome (salicylate) (sodium sulfonate)T49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
ChlorothymolT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
ChloroxineT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
ChrysarobinT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
CollagenaseT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Corn curesT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
DepilatoryT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Desloughing agentT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Diachylon plasterT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Dimethylamine sulfateT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
DithranolT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
EuresolT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Flowers of sulfurT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Fumaric acidT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
HairT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Hair::dyeT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Hair::preparation NECT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
HemostypticT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
IchthyolT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Keratolytic drug NECT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Keratolytic drug NEC::anthraceneT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Keratoplastic NECT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Lassar's pasteT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
MonobenzoneT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Podophyllum (resin)T49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Preparation, localT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Pyrithione zincT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
RubefacientT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Salicylic acidT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Salicylic acid::with benzoic acidT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Salicylic acid::congenersT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Salicylic acid::derivativeT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Salicylic acid::saltsT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Savin (oil)T49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
SelsunT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Sulfur, sulfurated, sulfuric, sulfurous, sulfuryl (compounds NEC) (medicinal)T49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Sulfur, sulfurated, sulfuric, sulfurous, sulfuryl (compounds NEC) (medicinal)::acidT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Sulfur, sulfurated, sulfuric, sulfurous, sulfuryl (compounds NEC) (medicinal)::dioxide (gas)T49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Sulfur, sulfurated, sulfuric, sulfurous, sulfuryl (compounds NEC) (medicinal)::etherT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Sulfur, sulfurated, sulfuric, sulfurous, sulfuryl (compounds NEC) (medicinal)::hydrogenT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Sulfur, sulfurated, sulfuric, sulfurous, sulfuryl (compounds NEC) (medicinal)::medicinal (keratolytic) (ointment) NECT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Sulfur, sulfurated, sulfuric, sulfurous, sulfuryl (compounds NEC) (medicinal)::ointmentT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Sulfur, sulfurated, sulfuric, sulfurous, sulfuryl (compounds NEC) (medicinal)::pesticide (vapor)T49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Sulfur, sulfurated, sulfuric, sulfurous, sulfuryl (compounds NEC) (medicinal)::vapor NECT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
ThioglycolateT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
TioxoloneT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
TriacetoxyanthraceneT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
TrioxysalenT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
Vleminckx's solutionT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6
XenysalateT49.4X1T49.4X2T49.4X3T49.4X4T49.4X5T49.4X6

Patient EducationClinical

Drug Reactions

Most of the time, medicines make our lives better. They reduce aches and pains, fight infections, and control problems such as high blood pressure or diabetes. But medicines can also cause unwanted reactions, such as drug interactions, side effects, and allergies.

The full article covers:

  • What is a drug interaction?
  • What are side effects?
  • What are drug allergies?
  • How can I stay safe when taking medicines?

Read the full article at MedlinePlus

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

Convert T49.4X5A to ICD-9-CMHistory

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

ICD-9-CM
995.29 Adv eff med/biol NEC/NOS
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
E946.4 Adv eff hair/scalp prep
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.

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 T49.4X5AOverview

Is T49.4X5A a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report adverse effect of keratolytics, keratoplastics, and other hair treatment drugs and preparations, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T49.4X5A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for adverse effect of keratolytics, keratoplastics, and other hair treatment drugs and preparations, such as an emergency visit or first evaluation.

What MS-DRG does T49.4X5A group to?

On inpatient claims, adverse effect of keratolytics, keratoplastics, and other hair treatment drugs and preparations, initial encounter maps to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.

Can T49.4X5A be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because adverse effect of keratolytics, keratoplastics, and other hair treatment drugs and preparations, initial encounter describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

What is the ICD-9 equivalent of T49.4X5A?

Under the General Equivalence Mappings, adverse effect of keratolytics, keratoplastics, and other hair treatment drugs and preparations, initial encounter converts to ICD-9-CM 995.29 (adv eff med/biol NEC/NOS) and E946.4 (adv eff hair/scalp prep). 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.