Headache Red Flags


There are MANY primary and secondary causes of headache:

Source: Mansoor AM. Frameworks for Internal Medicine. 2019

There are MANY causes of secondary intracranial headache:

Source: Mansoor AM. Frameworks for Internal Medicine. 2019

Consider the SNNOOP10 mnemonic for headache red flags!

  • S ystemic symptoms, including fever
  • N eoplasm history
  • N eurologic deficit
  • O nset is sudden, abrupt
  • O older age (onset >50 years)
  • P ositional headache
  • P attern change or recent onset of new headache
  • P recipitated by sneezing, coughing
  • P apilledema
  • P rogressive headache
  • P regnancy or puerperium
  • P ainful eye, autonomic features
  • P ost-traumatic onset
  • P athology of immune system
  • P ainkiller overuse


  • Age, gender profession
  • Duration of headache
  • Location/ irradiation
  • Intensity
  • Qualitative characteristics
  • What time of day does pain start and how long does it last
  • What is the frequency of the headaches
  • Triggering events, relieving and aggravating factors
  • Related symptoms
  • Medications and frequency of administration

HEADACHE with Systemic symptoms

  • Many possibilities: fever, nuchal rigidity, altered mental status, photophobia, confusion, petechial rash, weight loss, etc.

Evaluation: Consider head CT, LP, blood cultures

DDx: bacterial meningitis, encephalitis, fungal meningitis, aseptic meningitis, autoimmune neurosarcoidosis, Behcet syndrome

Abrupt-onset HEADACHE

  • Thunderclap headache that reaches maximal intensity within seconds to a minute
  • Explosive and unexpected
  • May have associated neurological deficits (e.g., hemiparesis, oculomotor deficits)
  • Consider history of anticoagulant use or trauma, nausea, vomiting, or meningismus

Evaluation: Consider head CT, LP (xanthochromia?)

DDx: Subarachnoid hemorrhage, AVM rupture, aneurysm rupture, reversible cerebral vasoconstriction syndrome

Positional headache

  • Headache with upright or sitting position
  • Resolves with recumbency
  • May be associated with tinnitus, vertigo, dizziness, nuchal rigidity/pain, unsteady gait, diaphoresis, anorexia, etc.

Evaluation: Consider MRI brain/spine, LP

DDx: Spontaneous hypotension headache, post-LP CSF leak, CSF shunt malfunction, cervicogenic, Chiari I malformation 

HEADACHE Aggravated by coughing/sneezing

  • Aggravated by valsalva, cough or bending over
  • May be associated with nausea, vomiting, fever, worsening/progressive headache, focal neurological deficits, papilledema, new-onset seizures, fatigue, or cognitive dysfunction

Evaluation: Consider MRI brain (vs head CT), LP

DDx: Primary intracranial tumors, metastasis, abscesses, chronic subdural hematoma, ICP

New-onset headache in older patient

  • Patients over 50 years or age
  • May be associated with fever, fatigue, weight loss, jaw claudication, diplopia, or transient monocular vision loss

Evaluation: Consider temporal artery biopsy, head CT, color doppler ultrasound

DDx: Giant cell arteritis, trigeminal neuralgia, acute herpes zoster, post herpetic neuralgia 

headache with Blurry vision

  • Blurry vision has many forms: diplopia, vision loss, etc.
  • May be associated with nausea, loss of coordination and balance, headaches upon waking early in the morning, or unilateral blurry vision/seeing halos

Evaluation: Consider fundoscopy, head CT, LP (elevated opening pressure?) 

DDx: Pseudotumor cerebri, hydrocephalus, tumor, acute hypertension, glaucoma, cavernous sinus thrombosis 

headache with Painful eye

  • May have associated autonomic features (e.g., lacrimation, miosis, ptosis, rhinorrhea), conjunctival injection, vision loss, seeing halos

Evaluation: Consider fundoscopy, MRI brain

DDx: Optic neuritis, glaucoma, cluster headache, migraine, trigeminal autonomic cephalgia, Cavernous sinus thrombosis, draining AVM

Post-traumatic headache

  • Any recent trauma or injury?
  • May have associated confusion, loss of consciousness, memory loss, acute worsening

Evaluation: head CT vs MRI brain

DDx: Concussion syndrome, TBI

headache with Acute neck pain

  • May have associated Horner’s syndrome or focal deficits

Evaluation: Consider CTA, MRA, Doppler

DDx: Cervical artery dissection (carotid dissection, vertebral artery dissection)

headache in the immunosuppressed patient

  • May have associated low CD-4 count, photophobia, pain with eye movement, altered mental status, confusion, or focal deficits 

Evaluation: head CT, MRI brain, LP

DDx: Cryptococcal meningitis, toxoplasmosis, JC virus, acute HIV encephalitis

headache in Pregnancy / postpartum

  • Concerning features would include new onset, throbbing, diffuse (holocephalic), constant, blurry vision, photophobia, scotoma, diplopia, hemianopsia, focal deficits 

Evaluation: BP, Cr, fundoscopy, MRI brain or CT head

DDx: Preeclampsia with severe features (includes HA), cerebral venous thrombosis, stroke 

Case 1

24yo woman with history of IV drug use is admitted with shortness of breath and lower extremity edema. Overnight, she develops new onset headache and associated confusion. 

  • What are the red flags? 
  • What’s your DDx?
  • What would you do next?

Case 2

45yo woman presents with sudden onset severe headache, 2 episodes of vomiting, and photophobia without neurological deficit. 10 days ago, she was evaluated for these exact symptoms and underwent non-contrast head CT (unremarkable) followed by an LP (also unremarkable). She then saw a neurologist in follow-up who subsequently diagnosed her with reversible cranial vasoconstriction syndrome (RCVS).

  • What is your next step?

Case 3

24yo woman with homozygous factor V Leiden presents with sudden onset headaches after recently starting OCP.

  • What is likely cause of her headache?
  • What are the red flags?
  • In what other patients would you be concerned about this presentation?

Blog post based on Med-Peds Forum talk by Cecilia Paasche, PGY1, and Tabitha N’dungu, PGY1

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