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What to do if…
you have a sudden severe headache that is unusual for you

Short answer

If you have a sudden, severe headache that’s unusual for you—especially a “worst ever” headache—call 911 now and don’t drive yourself.

Do not do these things

  • Do not “sleep it off” if it started suddenly, is extremely severe, or comes with new neurological symptoms.
  • Do not drive yourself to the ER if you feel faint, confused, very drowsy, or your vision is affected.
  • Do not exceed label doses of pain medicines (and don’t double up on products that both contain acetaminophen).
  • Do not drink alcohol or take sedatives to dull symptoms.
  • Do not stay alone if symptoms are severe or changing.

What to do now

  1. Reduce immediate risk. Sit or lie down somewhere safe. If possible, have someone stay with you.
  2. Call 911 right away if any red flags are present (even if symptoms improve or go away):
    • Headache that came on suddenly and is very severe (thunderclap / “worst headache of my life”).
    • Possible stroke signs: face drooping, arm/leg weakness or numbness (especially one side), speech trouble, sudden vision problems, sudden severe dizziness/trouble walking.
    • Confusion, fainting, seizure, or you’re very drowsy/hard to wake.
    • Severe headache after a significant head injury.
    • Severe headache with fever and stiff neck, new rash, or you look/feel seriously ill.
    • Severe headache with a painful red eye or sudden major vision change.
  3. If you’re unsure, it’s reasonable to choose emergency evaluation. For a severe, unusual headache you can’t explain, go to the Emergency Department—and if you don’t have safe transport, or you feel worse while deciding, call 911 rather than driving.
  4. When you call 911 or arrive at the ER, give a tight “timeline + symptoms”:
    • Exact start time, how fast it peaked (seconds/minutes vs gradual), and what you were doing.
    • Any stroke-like symptoms, fever/neck stiffness, vomiting, confusion, or collapse.
    • Pregnancy/postpartum status, recent infection, recent head/neck injury, or unusual exertion.
    • Important meds: blood thinners, steroids, new prescriptions, or substance use that could matter medically.
  5. If pregnant or recently postpartum and you have a home blood pressure cuff: take a reading (if you can do so safely) and share the number with 911/EMS or the ER team. Do not delay calling 911 to do this.
  6. While waiting for help:
    • Keep your phone accessible; gather ID/insurance info if handy; list your meds/allergies (a photo is fine).
    • If nauseated, lie on your side to reduce choking risk if you vomit.
    • Avoid alcohol and sedatives. Small sips of water are usually OK unless you’re very drowsy, actively vomiting, or you’ve been told not to drink.

What can wait

  • Trying to self-diagnose online or asking friends to decide whether it’s “serious enough.”
  • Deciding which test you need or negotiating care plans before you’ve been evaluated.
  • Non-urgent responsibilities like driving home, finishing tasks, or replying to messages.

Important reassurance

Many headaches are not dangerous—but the specific pattern of sudden, severe, unusual headache is one that clinicians treat urgently because some causes are time-sensitive. Getting checked quickly is a protective choice, not an overreaction.

Scope note

This guide covers immediate first steps to keep you safe and get urgent evaluation. Longer-term decisions can come after you’ve been assessed.

Important note

This is general information, not medical advice or a diagnosis. If you think you may be having an emergency, call 911.

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