2027 ICD-10-CM Diagnosis Code R51.9Headache, unspecified
ICD-10-CM Codes›R00–R99›R50-R69›R51
- Billable — Valid for Submission
- Not Chronic
R51.9 is a billable ICD-10-CM diagnosis code for headache, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 102 through 103. As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Headache; including migraine and Nervous system signs and symptoms.
This medical diagnosis code is frequently used in Family Practice medical specialties to designate conditions such headache.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Aching headache
- Acute headache
- Acute pain in face
- Aural headache
- Bilateral headache
- Chronic orofacial pain
- Chronic orofacial pain due to disorder
- Chronic orofacial pain due to infectious disease
- Chronic orofacial pain due to nonvascular intracranial disorder
- Chronic orofacial pain due to temporomandibular joint disorder
- Chronic pain in face
- Chronic primary orofacial pain
- Chronic secondary facial pain
- Craniofacial pain
- Daily headache
- Delayed headache caused by alcohol
- Dental headache
- Effects of high altitude
- Frequent headache
- Frontal headache
- Frontal sinus pain
- Generalized headache
- Headache
- Headache caused by carbon monoxide
- Headache caused by high altitude
- Headache caused by monosodium glutamate
- Headache character - finding
- Headache disorder
- Headache due to acute angle closure
- Headache due to arterial hypertension
- Headache due to cold exposure
- Headache due to external compression of head
- Headache due to intracranial disease
- Headache due to intracranial neoplasm
- Headache due to reversible cerebral vasoconstriction syndrome
- Headache due to spontaneous subarachnoid hemorrhage
- Headache following myelography
- Heavy head
- Hindbrain hernia headache
- Intermittent headache
- Intolerance to monosodium glutamate
- Low pressure headache
- Maxillary sinus pain
- Morning headache
- Muscular headache
- Nasal headache
- Obstetric spinal and epidural anesthesia-induced headache
- Occipital headache
- Pain due to neoplastic disease
- Pain in cheek
- Pain in chin
- Pain in face
- Pain of head and neck region
- Pain of respiratory structure
- Pain radiating to head
- Parietal headache
- Post dural puncture headache
- Post-ictal state
- Postpartum headache
- Postseizure headache
- Referred pain
- Referred pain in face
- Shooting headache
- Shooting pain
- Sinus headache
- Temporal headache
- Tenderness of face
- Tenderness of head and neck region
- Tenderness of neck
- Tenderness of respiratory structure
- Tenderness of scalp
- Tenderness over frontal sinus
- Tenderness over maxillary sinus
- Throbbing headache
- Throbbing pain
- Unilateral headache
- Unilateral left sided headache
- Unilateral right sided headache
- Viral headache
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to R51.9: its own notes plus those printed at R51 and Chapter 18. A note printed at a category, block or chapter applies to every code under it.
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.
- Facial pain NOS
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.
Notes
General instructions on how these codes are used.
- 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.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name R51.9, its category, or a range that includes it.
Excludes1 2
These codes carry an Excludes1 note naming R51.9: they are not reported together with it, unless the two conditions are unrelated.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Headache R51.9
chronic daily R51.9
daily chronic R51.9
nasal septum R51.9
Pain (s) See Also: Painful; R52
face, facial R51.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Headache
the symptom of pain in the cranial region. it may be an isolated benign occurrence or manifestation of a wide variety of headache disorders.
Patient EducationClinical
Headache
Almost everyone has had a headache. Headache is the most common form of pain. It's a major reason people miss days at work or school or visit the doctor.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Code History & ChangesHistory
Replacement R51.9 replaces the following previously assigned code(s):
- R51 - Headache
Questions About R51.9Overview
What is the ICD-10 code for headache, unspecified?
The ICD-10-CM code for headache, unspecified is R51.9 (sometimes written as R519). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is R51.9 (Headache) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report headache, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does R51.9 group to?
When headache, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 102, 103, with relative weights from 0.8219 to 1.1200 depending on complications. Higher weights mean higher Medicare reimbursement.
Can R51.9 be a principal diagnosis?
Use it with care. This is a symptom code, so once a definitive diagnosis explaining the headache, unspecified is established, that condition takes the principal position instead.
