Headache Red Flags: When to Go to the ER

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Written and medically reviewed by Tae Ho Guak, MD, board-certified neurologist · Reviewed July 2026 · Editorial policy

Headache red flags requiring emergency assessment
Five headache red flags that need emergency care: thunderclap onset, fever with neck stiffness, focal deficit, first severe headache after 50, headache worse lying flat

Headaches are common, but not all are safe. Some secondary headaches can be life-threatening. If any of these 7 signs appear, go to the ER immediately.

1. Thunderclap Headache

Explosive onset within seconds — the worst headache of your life. Classic sign of subarachnoid hemorrhage.

2. First Headache After Age 50

New headache in middle age or later: suspect tumor, temporal arteritis, or other secondary causes.

3. Neurological Symptoms

  • Weakness or numbness on one side
  • Slurred speech
  • Blurred or double vision
  • Altered consciousness
  • Seizures

4. High Fever + Stiff Neck

Classic triad of meningitis. Call emergency services immediately.

5. Headache After Head Trauma

May indicate epidural or subdural hematoma. Never ignore post-traumatic headache even with a pain-free interval.

6. Worsening Despite Medication

Headache worsening progressively over days/weeks, or worst in the morning — consider intracranial hypertension or mass lesion.

7. Headache with Systemic Symptoms

Unexplained weight loss, night sweats, or persistent fever with headache may suggest malignancy or systemic infection.

Most headaches are primary and benign — but when in doubt, always get checked. → Back to Headache Information Library

References

  • Do TP, Remmers A, Schytz HW, et al. Red and orange flags for secondary headaches in clinical practice: SNNOOP10 list. Neurology. 2019;92(3):134–144.
  • Headache Classification Committee of the International Headache Society. The International Classification of Headache Disorders, 3rd edition. Cephalalgia. 2018;38(1):1–211.
  • American College of Radiology. ACR Appropriateness Criteria: Headache.

This article was written and medically reviewed by Tae Ho Guak, MD, a board-certified neurologist. Last reviewed July 2026. See our editorial policy.

From the textbook. Chapter 5, “Red Flags, Investigations and When to Image,” of my clinical textbook Headache Medicine covers this topic in full for doctors, with the evidence and decision pathways behind it. About the book →

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