Written and medically reviewed by Tae Ho Guak, MD, board-certified neurologist · Reviewed July 2026 · Editorial policy
Summary. If one side of your head has been hurting continuously for months, with occasional intensification accompanied by symptoms like tearing or nasal congestion, it may not be common migraine or tension-type headache, but rather hemicrania continua (ICHD-3 3.4). The most distinctive feature of this headache is its nearly 100% response to the anti-inflammatory analgesic indomethacin, and when accurately diagnosed, it is a “treatable chronic headache” that can improve dramatically. This makes delayed diagnosis particularly unfortunate in such cases.
Medical Background — What is Hemicrania Continua?
Hemicrania continua is a primary headache disorder classified under trigeminal autonomic cephalalgias (TACs) in the third edition of the International Classification of Headache Disorders (ICHD-3). It belongs to the same family as cluster headache but presents differently. The key feature is a “dual-layer structure”: a persistent background pain on one side (unilateral) that continues daily for more than 3 months, with exacerbation attacks layered on top where pain intensifies.
The core diagnostic criteria presented in ICHD-3 (3.4) are as follows (Headache Classification Committee of the International Headache Society, Cephalalgia 2018):
A. Unilateral headache satisfying criteria B–D.
B. Present daily and continuously for more than 3 months, with no pain-free periods.
C. At least one of the following: ① Cranial autonomic symptoms ipsilateral to the pain (conjunctival injection, tearing, nasal congestion, rhinorrhea, ptosis, pupillary miosis, etc.), ② Restlessness or agitation.
D. Complete response to therapeutic-dose indomethacin.
Criterion D is the most important. The absolute and complete response to indomethacin is the diagnostic hallmark of hemicrania continua and paroxysmal hemicrania, and serves as the decisive clue distinguishing them from other headaches. In clinical practice, the “indomethacin test” is commonly used, gradually titrating indomethacin (e.g., 25 mg → 50 mg → 75 mg in divided doses) to assess response. However, because this medication carries a risk of gastrointestinal side effects, it must be attempted only under a physician’s prescription and supervision with gastric protective strategies in place.
Diagnosis and Differentiation — How does it differ from similar-looking headaches?
Hemicrania continua is easily misdiagnosed as another chronic headache because of its “persistent one-sided pain” characteristic. Differentiation points are as follows:
Chronic Migraine: Often bilateral or alternating sides; characterized by pulsating quality, photophobia, phonophobia, and nausea. Does not show absolute response to indomethacin.
Cluster Headache: Clear pain-free periods exist; attacks are short (15 minutes to 3 hours), extremely severe, and cluster at night or in the early morning. Hemicrania continua differs in that “background pain is always present.”
Paroxysmal Hemicrania: Has the same indomethacin response but presents as short attacks (2–30 minutes) occurring multiple times daily, without persistent background pain.
Cervicogenic and Tension-Type Headache: Lack autonomic symptoms and indomethacin response.
Medication Overuse Headache: Can coexist when analgesics are used frequently and should be evaluated together.
Particularly when unilateral headache first develops or its characteristics change, it is standard practice to recommend brain imaging (usually contrast-enhanced MRI) to exclude secondary (symptomatic) causes. Some secondary headaches such as tumors, vascular lesions, or carotid artery dissection can present similarly to hemicrania continua (see SNNOOP10 red flag assessment).
Self-Management and Prevention — Accelerating diagnosis and maintaining daily life
From here, these are steps patients can take. Remember that hemicrania continua is not a condition you “cure yourself,” but rather one that “is well-managed with accurate diagnosis.” The greatest help is providing good information so medical professionals reach the correct answer quickly.
Keep a headache diary. Recording the pain location (whether always on the same side), whether it persists daily, the time of intensification, and whether tearing, nasal congestion, ptosis, and restlessness occur ipsilaterally will speed up diagnosis.
Track analgesic use frequency. If using over-the-counter analgesics 10–15 or more days per month, medication overuse headache may be superimposed, so inform your medical team.
Do not self-administer indomethacin long-term. Even diagnostic use requires prescription and gastric protection due to risks to the stomach, kidneys, and cardiovascular system. Even if effective, finding the minimum effective dose and monitoring for side effects is important.
For cases where long-term indomethacin is difficult, alternatives such as melatonin, topiramate, COX-2 inhibitors, greater occipital nerve block, and in some cases botulinum toxin or neuromodulation therapy are being studied and attempted. Which choice is appropriate depends on comorbidities, so consult a headache specialist.
Regular sleep, hydration, and meals with moderation of excess caffeine and alcohol are fundamentals for reducing exacerbation of all chronic headaches.
Warning Signs — Seek care promptly in these situations
Sudden headache reaching maximum intensity within one minute like a thunderclap (thunderclap headache)
Headache with fever, neck stiffness, and rash
When neurological abnormalities are present such as unilateral weakness, speech disturbance, visual field defect, or diplopia
New-onset headache after age 50, particularly with scalp or temporal tenderness or jaw pain when chewing
When baseline risk factors such as cancer, immunosuppression, or anticoagulant use exist and headache characteristics change
Progressively worsening headache or pain exacerbated by lying down or coughing
If any of these signs appear, do not conclude it is a primary headache and seek immediate medical evaluation.
Conclusion
“My one-sided head has been hurting for months, tests are normal, and medication doesn’t help much”—this is something we hear surprisingly often in the clinic. Some of these patients have hemicrania continua, a condition where a single medication, indomethacin, can completely transform quality of life. The four key clues are: unilateral, persistent, ipsilateral autonomic symptoms, and indomethacin response. Bring your headache diary and visit a headache specialist, saying, “Please also check for the possibility of hemicrania continua.” Finding the correct diagnosis is the beginning of treatment.
From the textbook. Chapter 30, “Hemicrania Continua,” of my clinical textbook Headache Medicine covers this topic in full for doctors, with the evidence and decision pathways behind it. About the book →