ICD-10-CM Code T42.6X5A

Adverse effect of other antiepileptic and sedative-hypnotic drugs, initial encounter

Version 2020 Replaced Code Billable Code Unacceptable Principal Diagnosis

Valid for Submission

T42.6X5A is a billable code used to specify a medical diagnosis of adverse effect of other antiepileptic and sedative-hypnotic drugs, initial encounter. The code is valid for the year 2020 for the submission of HIPAA-covered transactions. The ICD-10-CM code T42.6X5A might also be used to specify conditions or terms like acne of external chemical origin, acne of external chemical origin, adverse reaction to bromide, adverse reaction to carbromal derivative, adverse reaction to glutethimide, adverse reaction to methaqualone, etc

The code T42.6X5A describes a circumstance which influences the patient's health status but not a current illness or injury. The code is unacceptable as a principal diagnosis.

Short Description:Adverse effect of antiepileptic and sed-hypntc drugs, init
Long Description:Adverse effect of other antiepileptic and sedative-hypnotic drugs, initial encounter

Replaced Code

This code was replaced in the 2020 ICD-10 code set with the code(s) listed below. The National Center for Health Statistics (NCHS) has published an update to the ICD-10-CM diagnosis codes which became effective October 1, 2019. This code was replaced for the FY 2020 (October 1, 2019 - September 30, 2020).

  • K59.03 - Drug induced constipation

Code Edits

The Medicare Code Editor (MCE) detects and reports errors in the coding of claims data. The following ICD-10 Code Edits are applicable to this code:

  • 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.


The following clinical terms are approximate synonyms or lay terms that might be used to identify the correct diagnosis code:

  • Acne of external chemical origin
  • Acne of external chemical origin
  • Adverse reaction to bromide
  • Adverse reaction to carbromal derivative
  • Adverse reaction to glutethimide
  • Adverse reaction to methaqualone
  • Anticonvulsant drug-induced osteomalacia
  • Barbiturate antiepileptic adverse reaction
  • Beclamide adverse reaction
  • Bromide acne
  • Bromine acne
  • Bromine complexes adverse reaction
  • Bromoderma
  • Carbamate sedative adverse reaction
  • Chloral hydrate adverse reaction
  • Chloral sedative adverse reaction
  • Chlormethiazole adverse reaction
  • Chlormezanone adverse reaction
  • Fetal or neonatal effect of placental or breast transfer of anticonvulsant
  • Fetal valproate syndrome
  • Gabapentin adverse reaction
  • Lamotrigine adverse reaction
  • Metabolic acidosis due to ingestion of drugs AND/OR chemicals
  • Metabolic acidosis due to paraldehyde
  • Methyprylone adverse reaction
  • Osteomalacia secondary to drug
  • Paraldehyde adverse reaction
  • Piracetam adverse reaction
  • Primidone adverse reaction
  • Sodium valproate adverse reaction
  • Triclofos sodium adverse reaction
  • Vigabatrin adverse reaction
  • Zolpidem adverse reaction
  • Zopiclone adverse reaction

Convert T42.6X5A to ICD-9

  • 995.29 - Adv eff med/biol NEC/NOS (Combination Flag)
  • E936.3 - Adv eff antconvl NEC/NOS (Combination Flag)
  • 995.29 - Adv eff med/biol NEC/NOS (Combination Flag)
  • E937.8 - Adv eff sedat/hypnot NEC (Combination Flag)

Code Classification

  • Injury, poisoning and certain other consequences of external causes (S00–T98)
    • Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances (T36-T50)
      • Antiepileptic, sedative- hypnotic and antiparkinsonism drugs (T42)

Code History

  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016
    (First year ICD-10-CM implemented into the HIPAA code set)
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020

Information for Patients

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.

One problem is interactions, which may occur between

  • Two drugs, such as aspirin and blood thinners
  • Drugs and food, such as statins and grapefruit
  • Drugs and supplements, such as ginkgo and blood thinners
  • Drugs and diseases, such as aspirin and peptic ulcers

Interactions can change the actions of one or both drugs. The drugs might not work, or you could get side effects.

Side effects are unwanted effects caused by the drugs. Most are mild, such as a stomach aches or drowsiness, and go away after you stop taking the drug. Others can be more serious.

Drug allergies are another type of reaction. They can be mild or life-threatening. Skin reactions, such as hives and rashes, are the most common type. Anaphylaxis, a serious allergic reaction, is more rare.

When you start a new prescription or over-the-counter medication, make sure you understand how to take it correctly. Know which other medications and foods you need to avoid. Ask your health care provider or pharmacist if you have questions.

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