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ICD-10-CM 2027 diagnosis code

G40.5Epileptic seizures related to external causes

Not billable — use a more specific code

G40.5 is a header code, so it can't be reported by itself. Choose one of the 1 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About G40.5

G40.5 is the ICD-10-CM diagnosis code for epileptic seizures related to external causes. It belongs to category G40 (epilepsy and recurrent seizures), block G40-G47 (episodic and paroxysmal disorders) and chapter 6 (diseases of the nervous system). It is a header code, so it can't be reported by itself; one of its 1 subcodes must be used instead.

Within G40 (epilepsy and recurrent seizures), G40.5 is specifically for epileptic seizures related to external causes. Related codes cover Localization-related (focal) (partial) idiopathic epilepsy and epileptic syndromes with seizures of localized onset (G40.0), Localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures (G40.1), Localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with complex partial seizures (G40.2), generalized idiopathic epilepsy and epileptic syndromes (G40.3), other generalized epilepsy and epileptic syndromes (G40.4), other epilepsy and recurrent seizures (G40.8), epilepsy, unspecified (G40.9), absence epileptic syndrome (G40.A) and 2 more.

To report this condition, pick the subcode that matches the documentation: G40.50 (not intractable).

Use an additional code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under G40.5

Coding notes

Applicable toConditions and synonyms classified to this code
  • Epileptic seizures related to alcohol
  • Epileptic seizures related to drugs
  • Epileptic seizures related to hormonal changes
  • Epileptic seizures related to sleep deprivation
  • Epileptic seizures related to stress
Use additional codeAdd a secondary code to fully describe the condition
  • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
Code alsoTwo codes may be needed; sequencing depends on circumstances
  • , if applicable, associated epilepsy and recurrent seizures (G40.-)

Notes that apply from higher levels

Instructions written at a parent level also apply to G40.5.

› From G40 Epilepsy and recurrent seizures
Note
  • the following terms are to be considered equivalent to intractable: pharmacoresistant (pharmacologically resistant), treatment resistant, refractory (medically) and poorly controlled
Excludes1
  • conversion disorder with seizures (F44.5)
  • convulsions NOS (R56.9)
  • post traumatic seizures (R56.1)
  • seizure (convulsive) NOS (R56.9)
  • seizure of newborn (P90)
Excludes2

Broader instructions also apply from Chapter 6: Diseases of the nervous system.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about G40.5

Is G40.5 billable?

No. G40.5 is a header code. Report one of its more specific subcodes instead.