2021 ICD-10-CM Diagnosis Code R51.9

Headache, unspecified

    2021 - New Code Billable/Specific Code
  • R51.9 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • ICD-10-CM R51.9 is a new 2021 ICD-10-CM code that became effective on October 1, 2020.
  • This is the American ICD-10-CM version of R51.9 - other international versions of ICD-10 R51.9 may differ.
Applicable To
  • Facial pain NOS
The following code(s) above R51.9 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to R51.9:
  • R00-R99
    2021 ICD-10-CM Range R00-R99

    Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified

    Note
    • This chapter includes symptoms, signs, abnormal results of clinical or other investigative procedures, and ill-defined conditions regarding which no diagnosis classifiable elsewhere is recorded.
    • Signs and symptoms that point rather definitely to a given diagnosis have been assigned to a category in other chapters of the classification. In general, categories in this chapter include the less well-defined conditions and symptoms that, without the necessary study of the case to establish a final diagnosis, point perhaps equally to two or more diseases or to two or more systems of the body. Practically all categories in the chapter could be designated 'not otherwise specified', 'unknown etiology' or 'transient'. The Alphabetical Index should be consulted to determine which symptoms and signs are to be allocated here and which to other chapters. The residual subcategories, numbered .8, are generally provided for other relevant symptoms that cannot be allocated elsewhere in the classification.
    • The conditions and signs or symptoms included in categories R00-R94 consist of:
    • (a) cases for which no more specific diagnosis can be made even after all the facts bearing on the case have been investigated;
    • (b) signs or symptoms existing at the time of initial encounter that proved to be transient and whose causes could not be determined;
    • (c) provisional diagnosis in a patient who failed to return for further investigation or care;
    • (d) cases referred elsewhere for investigation or treatment before the diagnosis was made;
    • (e) cases in which a more precise diagnosis was not available for any other reason;
    • (f) certain symptoms, for which supplementary information is provided, that represent important problems in medical care in their own right.
    Type 2 Excludes
    • abnormal findings on antenatal screening of mother (O28.-)
    • certain conditions originating in the perinatal period (P04-P96)
    • signs and symptoms classified in the body system chapters
    • signs and symptoms of breast (N63, N64.5)
    Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
  • R51
    ICD-10-CM Diagnosis Code R51

    Headache

      2016 2017 2018 2019 2020 2021 - Converted to Parent Code Non-Billable/Non-Specific Code
    Type 2 Excludes
    • atypical face pain (G50.1)
    • migraine and other headache syndromes (G43-G44)
    • trigeminal neuralgia (G50.0)
    Headache
ICD-10-CM R51.9 is grouped within Diagnostic Related Group(s) (MS-DRG v38.0):
  • 102 Headaches with mcc
  • 103 Headaches without mcc
Code History
  • 2021 (effective 10/1/2020): New code
Code annotations containing back-references to R51.9:
  • Type 1 Excludes: R52
    , G43
    , G44
    ICD-10-CM Diagnosis Code R52

    Pain, unspecified

      2016 2017 2018 2019 2020 2021 Billable/Specific Code
    Applicable To
    • Acute pain NOS
    • Generalized pain NOS
    • Pain NOS
    Type 1 Excludes
    • acute and chronic pain, not elsewhere classified (G89.-)
    • localized pain, unspecified type - code to pain by site, such as:
    • abdomen pain (R10.-)
    • back pain (M54.9)
    • breast pain (N64.4)
    • chest pain (R07.1-R07.9)
    • ear pain (H92.0-)
    • eye pain (H57.1)
    • headache (R51.9)
    • joint pain (M25.5-)
    • limb pain (M79.6-)
    • lumbar region pain (M54.5)
    • pelvic and perineal pain (R10.2)
    • shoulder pain (M25.51-)
    • spine pain (M54.-)
    • throat pain (R07.0)
    • tongue pain (K14.6)
    • tooth pain (K08.8)
    • renal colic (N23)
    • pain disorders exclusively related to psychological factors (F45.41)
    ICD-10-CM Diagnosis Code G43

    Migraine

      2016 2017 2018 2019 2020 2021 Non-Billable/Non-Specific Code
    Note
    • the following terms are to be considered equivalent to intractable: pharmacoresistant (pharmacologically resistant), treatment resistant, refractory (medically) and poorly controlled
    Type 1 Excludes
    Type 2 Excludes
    • headache syndromes (G44.-)
    Use Additional
    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
    ICD-10-CM Diagnosis Code G44

    Other headache syndromes

      2016 2017 2018 2019 2020 2021 Non-Billable/Non-Specific Code
    Type 1 Excludes
    Type 2 Excludes
    • atypical facial pain (G50.1)
    • headache due to lumbar puncture (G97.1)
    • migraines (G43.-)
    • trigeminal neuralgia (G50.0)
  • Type 2 Excludes: G89
    ICD-10-CM Diagnosis Code G89

    Pain, not elsewhere classified

      2016 2017 2018 2019 2020 2021 Non-Billable/Non-Specific Code
    Code Also
    • related psychological factors associated with pain (F45.42)
    Type 1 Excludes
    • generalized pain NOS (R52)
    • pain disorders exclusively related to psychological factors (F45.41)
    • pain NOS (R52)
    Type 2 Excludes

Diagnosis Index entries containing back-references to R51.9:
  • Headache R51.9
    • chronic daily R51.9
    • daily chronic R51.9
    • nasal septum R51.9
  • Pain(s) R52
    - see also Painful
    ICD-10-CM Diagnosis Code R52

    Pain, unspecified

      2016 2017 2018 2019 2020 2021 Billable/Specific Code
    Applicable To
    • Acute pain NOS
    • Generalized pain NOS
    • Pain NOS
    Type 1 Excludes
    • acute and chronic pain, not elsewhere classified (G89.-)
    • localized pain, unspecified type - code to pain by site, such as:
    • abdomen pain (R10.-)
    • back pain (M54.9)
    • breast pain (N64.4)
    • chest pain (R07.1-R07.9)
    • ear pain (H92.0-)
    • eye pain (H57.1)
    • headache (R51.9)
    • joint pain (M25.5-)
    • limb pain (M79.6-)
    • lumbar region pain (M54.5)
    • pelvic and perineal pain (R10.2)
    • shoulder pain (M25.51-)
    • spine pain (M54.-)
    • throat pain (R07.0)
    • tongue pain (K14.6)
    • tooth pain (K08.8)
    • renal colic (N23)
    • pain disorders exclusively related to psychological factors (F45.41)

ICD-10-CM Codes Adjacent To R51.9
R50 Fever of other and unknown origin
R50.2 Drug induced fever
R50.8 Other specified fever
R50.81 Fever presenting with conditions classified elsewhere
R50.82 Postprocedural fever
R50.83 Postvaccination fever
R50.84 Febrile nonhemolytic transfusion reaction
R50.9 Fever, unspecified
R51 Headache
R51.0 Headache with orthostatic component, not elsewhere classified
R51.9 Headache, unspecified
R52 Pain, unspecified
R53 Malaise and fatigue
R53.0 Neoplastic (malignant) related fatigue
R53.1 Weakness
R53.2 Functional quadriplegia
R53.8 Other malaise and fatigue
R53.81 Other malaise
R53.82 Chronic fatigue, unspecified
R53.83 Other fatigue
R54 Age-related physical debility

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.