ICD-10-CM 2027
ICD-10 code for headache
Confirmed by the official ICD-10-CM index entry “headache”. Page updated September 29, 2026.
About coding headache
The ICD-10-CM code for headache is R51.9 (Headache, unspecified). The official index lists 41 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on R51.9.
Within R51, choose R51.9 (unspecified) only when documentation doesn't support a more specific option: with orthostatic component, not elsewhere classified (R51.0).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 102 (Headaches with MCC, relative weight 1.1201) and DRG 103 (Headaches without MCC, relative weight 0.822), in MDC 01 (Diseases and Disorders of the Nervous System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Related Headache codes
- G44.001 Cluster headache syndrome, unspecified, intractable
- G44.009 Cluster headache syndrome, unspecified, not intractable
- G44.011 Episodic cluster headache, intractable
- G44.019 Episodic cluster headache, not intractable
- G44.021 Chronic cluster headache, intractable
- G44.029 Chronic cluster headache, not intractable
- G44.031 Episodic paroxysmal hemicrania, intractable
- G44.039 Episodic paroxysmal hemicrania, not intractable
- G44.041 Chronic paroxysmal hemicrania, intractable
- G44.049 Chronic paroxysmal hemicrania, not intractable
- G44.051 Short lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT), intractable
- G44.059 Short lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT), not intractable
- G44.091 Other trigeminal autonomic cephalgias (TAC), intractable
- G44.099 Other trigeminal autonomic cephalgias (TAC), not intractable
- G44.1 Vascular headache, not elsewhere classified
- G44.201 Tension-type headache, unspecified, intractable
- G44.209 Tension-type headache, unspecified, not intractable
- G44.211 Episodic tension-type headache, intractable
- G44.219 Episodic tension-type headache, not intractable
- G44.221 Chronic tension-type headache, intractable
- G44.229 Chronic tension-type headache, not intractable
- G44.301 Post-traumatic headache, unspecified, intractable
- G44.309 Post-traumatic headache, unspecified, not intractable
- G44.311 Acute post-traumatic headache, intractable
- G44.319 Acute post-traumatic headache, not intractable
- G44.321 Chronic post-traumatic headache, intractable
- G44.329 Chronic post-traumatic headache, not intractable
- G44.40 Drug-induced headache, not elsewhere classified, not intractable
- G44.41 Drug-induced headache, not elsewhere classified, intractable
- G44.51 Hemicrania continua
- G44.52 New daily persistent headache (NDPH)
- G44.53 Primary thunderclap headache
- G44.59 Other complicated headache syndrome
- G44.81 Hypnic headache
- G44.82 Headache associated with sexual activity
- G44.83 Primary cough headache
- G44.84 Primary exertional headache
- G44.85 Primary stabbing headache
- G44.86 Cervicogenic headache
- G44.89 Other headache syndrome
- R51.0 Headache with orthostatic component, not elsewhere classified
Common questions about headache ICD-10 codes
What is the ICD-10 code for headache?
- R51.9 — Headache, unspecified. More specific codes apply when the documentation supports them: G44.001, G44.009, G44.011, G44.019 and others below.
What is the ICD-10 code for cluster headache syndrome, unspecified, intractable?
- G44.001 — Cluster headache syndrome, unspecified, intractable.
What is the ICD-10 code for cluster headache syndrome, unspecified, not intractable?
- G44.009 — Cluster headache syndrome, unspecified, not intractable.
What is the ICD-10 code for episodic cluster headache, intractable?
- G44.011 — Episodic cluster headache, intractable.
What is the ICD-10 code for episodic cluster headache, not intractable?
- G44.019 — Episodic cluster headache, not intractable.
What is the ICD-10 code for chronic cluster headache, intractable?
- G44.021 — Chronic cluster headache, intractable.
What is the ICD-10 code for chronic cluster headache, not intractable?
- G44.029 — Chronic cluster headache, not intractable.
Is R51.9 billable?
- Yes. R51.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can R51.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict R51.9 as a principal diagnosis.
Is R51.9 a CC or MCC?
- No. R51.9 is neither a CC nor an MCC under MS-DRG v44.0.