What are the characteristic sensations of a post‑viral headache in adults?

Post-Viral Headache Characteristics

Post-viral headaches typically present as moderate to severe, persistent, constant pain that is often holocephalic (affecting the entire head) with a pulsating or throbbing quality, frequently resembling migraine or new daily persistent headache patterns, and are notably treatment-refractory to standard over-the-counter analgesics. 1, 2

Primary Clinical Features

Post-viral headaches, particularly following COVID-19, demonstrate several characteristic sensations:

• Constant, unremitting pain that becomes continuous within 24 hours of onset and persists for months, distinguishing it from episodic headache patterns 1, 3
• Moderate to severe intensity that is debilitating and interferes with daily function, with full-time employment dropping from 81% to 55% in affected patients 2
• Pulsating or throbbing quality affecting the entire head (holocephalic distribution) rather than being localized to one side 1
• Lack of response to typical treatments including acetaminophen, ibuprofen, and even migraine-specific medications like triptans that previously provided relief 1

Associated Symptoms and Phenotypes

The headache phenotype varies but commonly includes:

• Migrainous features are present in 74% of cases, with photophobia, phonophobia, and nausea, though these classic migraine accompaniments may be absent in some presentations 2
• Chronification pattern where 65% of patients meet criteria for chronic migraine (≥15 headache days per month), even among those who previously had only episodic headaches 2
• New onset in previously headache-free individuals, presenting as a completely novel syndrome without prior headache history 1, 2

Duration and Persistence

• Protracted course averaging 7.4 months after viral infection, with some cases extending to 12-15 months 2, 4
• Persistent daily symptoms meeting criteria for new daily persistent headache (NDPH), where pain becomes continuous and non-remitting within 24 hours and lasts more than 3 months 3

Red Flag Features Requiring Urgent Evaluation

Certain presentations indicate serious complications rather than benign post-viral headache:

• Progressive worsening over days accompanied by confusion, altered mental status, or personality changes suggests encephalitis rather than simple post-viral headache 5, 4
• Seizures or focal neurological deficits indicate cerebral involvement requiring immediate brain imaging and lumbar puncture 5, 4
• Severe respiratory distress or signs of meningism (neck stiffness, photophobia) warrant cerebrospinal fluid analysis to exclude bacterial meningitis 5, 6

Distinguishing From Other Headache Types

Post-viral headaches differ from other common headache presentations:

• Unlike post-lumbar puncture headache, post-viral headaches do not worsen when upright or improve when lying flat (no positional component) 5
• Unlike tension-type headache, the pain is typically more severe, persistent, and associated with greater disability 1, 2
• Unlike typical migraine, there is often absence of clear triggers, aura, or complete response to standard migraine abortive therapy 1

Treatment Response Patterns

• Standard analgesics provide minimal relief, with patients reporting persistent symptoms despite trials of NSAIDs and acetaminophen 1
• Migraine preventive medications show some efficacy, with 72% of patients reporting decreased frequency or severity when started on preventive therapies indicated for migraine management 2
• Immunomodulatory therapy (high-dose corticosteroids) has shown good therapeutic response in cases meeting criteria for new daily persistent headache, supporting a neuroinflammatory mechanism 3
• CGRP monoclonal antibodies may provide dramatic relief in select cases, suggesting trigeminovascular system activation as a key mechanism 7

Common Clinical Pitfalls

• Do not dismiss persistent headache as "just fatigue" or a minor post-viral symptom, as it may indicate encephalitis or progression to severe neurological disease requiring immediate investigation 4
• Do not assume all post-viral headaches are benign—CNS involvement occurs in 36.4% of COVID-19 cases overall and 45.5% in severe disease, presenting with headache alongside confusion, corticospinal tract signs, and dysexecutive syndrome 5
• Do not overlook headache as a non-respiratory symptom of ongoing viral illness, as it is present in 7.2% of acute COVID-19 cases and persists in 50% of patients 12-15 months after infection 4