Headache Red Flags: When a Headache Is an Emergency and When It Can Wait
Written by Naurah Gaspard, DNP, FNP-C, FNP-BC · Medically reviewed by Cherlie Joseph, MSN, FNP-BC · Updated November 2026
Most headaches are tension headaches or migraines and are not dangerous. Call 911 for a sudden, explosive headache that peaks within a minute, a headache with stroke signs such as weakness or trouble speaking, fever with a stiff neck, confusion, a seizure, or a headache after a head injury. A new or changing headache pattern, especially after age 50 or during pregnancy, should be checked soon.
In this guide
Primary vs secondary headaches
A primary headache is the condition itself: tension-type headache, migraine and cluster headache. They can be painful and disruptive, but they are not caused by damage or disease elsewhere. A secondary headache is a symptom of something else, such as an infection, bleeding in or around the brain, a blood clot, very high blood pressure, a head injury or carbon monoxide exposure.
Red flags are the clues that a headache might be secondary. Clinicians often use a checklist called SNNOOP10 to screen for them. You do not need to memorize it; the practical version is below.
Call 911 right away for these
These can signal a stroke, brain bleed, meningitis or another emergency. Do not drive yourself, and do not wait to see if it passes.
- Thunderclap headache: a sudden, explosive headache that reaches full strength within about a minute, often described as the worst headache of your life. This is the classic sign of bleeding around the brain.
- Stroke signs: face drooping, arm or leg weakness or numbness, slurred or confused speech, sudden vision loss or trouble walking.
- Fever with a stiff neck, a new rash, confusion or unusual sleepiness, which can point to meningitis.
- Seizure, fainting or confusion with a headache.
- Headache after a head injury, especially with vomiting, drowsiness or if you take a blood thinner.
- Several people in the same home with headache, dizziness and nausea, particularly when a generator, gas appliance or car is running nearby. Get everyone into fresh air first; this may be carbon monoxide poisoning.
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These are not always emergencies, but they need a prompt, in-person evaluation:
| Red flag | Why it matters |
|---|---|
| New headache after age 50 | Higher chance of a secondary cause, including giant cell arteritis (with scalp tenderness, jaw pain when chewing or vision changes) |
| Headache that keeps getting worse over days or weeks | Can signal pressure inside the skull |
| A clear change from your usual pattern | New features, frequency or severity deserve a fresh look |
| Headache that is worse lying down or standing, or with coughing or straining | Can point to pressure changes inside the head |
| Headache during pregnancy or after giving birth | Can be a sign of preeclampsia, especially with high blood pressure, vision changes or swelling |
| New headache with cancer, HIV or a weakened immune system | Higher risk of infection or spread to the brain |
| Aura that lasts more than an hour or includes weakness | Needs evaluation to rule out stroke |
Headaches that can usually wait for a routine visit
Most headaches are not dangerous. These can usually be handled at a scheduled visit or with home care:
- A familiar headache that matches your usual tension or migraine pattern
- Headaches linked to a clear cause, such as a cold, a missed meal, poor sleep, dehydration on a hot Florida day or caffeine withdrawal
- A sinus-type headache with congestion
- Headaches that are getting more frequent but have no red flags; this is a good time to talk about prevention
Watch your pain-reliever use. Taking pain medicine or triptans on many days a month can cause medication overuse headache, which NINDS notes can worsen attacks or cause new headache symptoms.
How OurTopClinic can help
OurTopClinic is an online clinic and is not for emergencies. If you have any red flag above, call 911 or go to the nearest emergency room. For familiar headaches, we can help with a prevention plan or a refill of a medicine that already works for you. A provider will review whether it is appropriate. We do not prescribe controlled substances, such as butalbital combinations or opioids.
Get in-person care or call 911 if you have:
- A sudden, explosive headache that reaches full strength within about a minute
- Weakness, numbness, facial droop, slurred speech, vision loss or trouble walking
- Fever with a stiff neck, a new rash, confusion or a seizure
- A headache after a head injury, especially if you take a blood thinner
- Headache, dizziness and nausea in several people at home, especially with a generator or gas appliance running
Frequently asked questions
What does a thunderclap headache feel like?
It is a sudden, severe headache that hits like a clap of thunder and reaches its peak within about a minute. People often call it the worst headache of their life. It needs emergency care right away, even if it starts to ease.
When is a headache a sign of a stroke?
Be concerned when a headache comes with sudden weakness or numbness on one side, facial droop, trouble speaking or understanding, vision loss, or loss of balance. Call 911 and note the time symptoms started.
Can high blood pressure cause a headache?
Usually not at typical high readings. A severe headache with a very high reading, chest pain, shortness of breath, confusion or vision changes is an emergency. Check your blood pressure if you have a home monitor, but do not delay calling 911.
Sources
Keep reading
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- Telehealth vs urgent care
- Back pain red flags
- Browse all conditions and treatments A to Z
Already treated for migraines and need a refill?
$79 refill review by a nurse practitioner licensed in your state. Adults 18+ in FL, NM, OR and WA.
Request a medication refill →
Naurah Gaspard, DNP, FNP-C, FNP-BC
Board-certified family nurse practitioner licensed in Florida, New Mexico, Oregon and Washington, caring for adults online at OurTopClinic. Meet our providers.
This article is for general education and is not a substitute for medical advice. Treatment, including any prescription, is decided by a licensed provider after reviewing your health history. OurTopClinic is not for emergencies; if you have a medical emergency, call 911. OurTopClinic serves adults located in Florida, New Mexico, Oregon and Washington. Learn more at ourtopclinic.com.
