One of the first things you learn when working up chief complaints is to watch for “red flags.”
The problem isn’t remembering them. It’s that in real life, it can be hard to tell what’s actually serious versus what’s just severe, dramatic, or poorly described by the patient.
“Benign” sometimes looks severe. Migraines can be really intense. Patients aren’t the best historians.
That’s where most new grads tend to get stuck.
So instead of memorizing a massive differential, I like to keep it simple:
- Know the handful of red flags that actually matter
- Know what those red flags look like in real patients
- Know what “normal” can look like so you don’t work up everything
- Then document what you actually saw
TL;DR — What Actually Matters With Headaches
Purpose: Help you separate dangerous headaches from benign ones.
Do this first: Clarify onset and pattern. How fast did it start? Is it new or different?
Red flags: Thunderclap onset, focal neurologic deficits, fever with neck stiffness, altered mental status, new headache in higher-risk patients.
Initial checks: Vitals, focused neuro exam, mental status assessment, neck range of motion, risk factors.
First-line mindset: Don’t chase every symptom. Look for pattern + context.
Follow-up: If red flags are present or something feels objectively abnormal, send them for STAT imaging. If the exam is normal and the pattern fits a benign cause, document clearly and give clear return precautions.
What’s a “Red Flag” and What’s Actually Normal
1. “Thunderclap” Headache
What it looks like: A headache that reaches maximum intensity, fast (within seconds to minutes). Patients might say:
- “This is absolutely the worst headache of my life”
- “It hit me out of nowhere”
- “I was totally fine, then I wasn’t”
Why we care:
This pattern is classic for subarachnoid hemorrhage until proven otherwise. The concern isn’t just how bad it hurts, but also how fast it came on.
What’s common (and often normal):
- Gradual onset headaches that worsen over hours
- Headaches that feel similar to prior migraines or tension headaches
- Severe pain that escalates but does not peak instantly
What’s not normal:
- Sudden onset at full intensity
- Headache associated with syncope or neurologic symptoms
What to do:
These patients need urgent imaging and higher-level evaluation to rule out other SAH or other scary pathology.
2. New Focal Neurologic Deficits
What it looks like: unilateral weakness, gait changes, numbness, true speech difficulty, vision loss, facial droop.
What’s common (and often normal):
- Visual aura with migraine
- Scintillating scotomas (flickering, glittering, pulsing)
- Photophobia
- Nausea
- Tearing or rhinorrhea with cluster headaches (autonomic symptoms)
These symptoms can be painful or uncomfortable for the patient but they’re not true focal deficits.
What’s not normal:
- New or persistent focal deficits
- Objectively abnormal exam findings
- Symptoms that don’t follow a patient’s usual migraine pattern
What to do:
- Slow down and do a real neuro exam.
- Check strength side to side.
- Have them smile.
- Listen to their speech.
- Test visual fields.
- Watch them walk.
If you find anything objectively abnormal or something feels off, send them for urgent imaging.
If the exam is completely normal and the symptoms fit their typical headache pattern, document that clearly and move forward with appropriate treatment and return precautions.
Example: “Neuro exam without focal deficits. Strength and sensation intact bilaterally. Speech clear. Cranial nerves grossly intact. Normal gait.”
3. Fever or Neck Stiffness
This one can be tricky because patients (especially kids) will say “my neck hurts” when they’re sick.
The concern here is more about inability, not discomfort. A patient who feels bad with a headache is very different from a patient who looks sick and can’t tolerate light or move their neck.
What it looks like: Headache with fever, chills, neck pain, or difficulty flexing the neck.
Why we care:
Meningitis and CNS infections can manifest with these symptoms.
What’s common (and often normal):
- Generalized body aches
- Posterior neck soreness with viral illness
- Tender cervical lymph nodes
- A kid who says their neck hurts but can:
- Turn their head side to side
- Look up and down
- Touch chin to chest without resistance
What’s not normal
- True neck stiffness with limited range of motion
- Pain or resistance when flexing the neck forward
- Photophobia or persistent vomiting
- Patient looks ill or “off”.
What to do (and document):
- Can they actively flex their neck?
- Any resistance or pain with passive movement?
- Photophobia present or absent
- Overall appearance: well vs ill-appearing
- Mental status at baseline
4. Altered Mental Status
What it looks like: Confusion, lethargy, personality changes, difficulty answering basic questions, or not acting like themselves.
Why we care: Intracranial pathology, infection, metabolic issues, and intoxication can manifest with these symptoms.
What’s common (and often normal):
- Fatigue from pain or poor sleep
- Irritability
- Anxiety
What’s not normal:
- Confusion or disorientation
- Trouble following commands
- Inappropriate answers to questions
- Personality changes reported by family
- Slowed responses that don’t improve during the visit
What to do (and document):
Altered mental status means a change from baseline, so ask:
- Is this new for this patient?
- Are they oriented appropriately for age?
- Can they follow a multi-step command?
Document clearly:
- Orientation — Ex. “Patient correctly states name, location, date, and reason for visit.”
- Attention and command following — Ex. “Follows 2-step commands without difficulty.”
- Speech — Ex. Clear vs slurred. Fluent vs word-finding difficulty. Appropriate responses to questions.
- Behavior and interaction — Ex. Engaged vs withdrawn. Appropriate affect. Makes eye contact. Responds appropriately.
- Family/caregiver input — Ex. “Per spouse, patient at baseline.” Or, “Family reports new confusion starting this morning.”
5. New Headache in Higher-Risk Patients
This one isn’t about the headache itself, it’s about who is having it.
What it looks like:
Headaches that sound benign but occur in:
- Older patients (especially new headaches over age 50)
- Those with a history of cancer
- Immunocompromised patients
- Pregnant or postpartum patients
- Patients with a known clotting disorders or anticoagulation use
Why we care:
The same headache pattern that’s benign in a 22-year-old can mean something very different in a 65-year-old with new symptoms as these patients are more likely to have secondary causes.
What’s common (and often normal):
- Tension-type headaches from stress or poor sleep
- Medication-related headaches
- Dehydration
- Viral illness
What’s not normal:
- Headache that’s new or clearly different from baseline
- Progressive headaches worsening over days to weeks
- Headache with systemic symptoms (weight loss, fevers, night sweats)
- Any neurologic changes, even subtle ones
- Headache that doesn’t respond at all to usual treatment
What to do:
Lower your threshold to pause and reassess.
Focus on:
- Is this headache new for them?
- How is it different from prior headaches?
- Any history that raises concern for secondary causes?
- Are red flags stacking on top of each other?
Context matters more than just the degree of pain.
Final Thoughts
If you take nothing else from this, take this: context matters.
Ask good questions and clarify when you’re unsure. Do a real neuro exam. Look at the patient. Clearly document what you found and your thought process.
If you want a fast way to double-check your red flags, differential, and “does this patient need a higher level of care” thinking, this is exactly why we built Blox IQ.
The AI feature inside Blox is designed to give short, structured answers that fit real clinical workflow.
Example prompt you could use: “How do I work up a 40-year-old female with new onset headache and no focal neuro deficits?”
Use it as a second set of eyes, not a replacement for yours.
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