Ten Signs a Headache is Serious

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Headaches are one of the most common reasons that people come to see a doctor.  While the headache can be debilitating and extremely painful, most of the time headaches aren’t a sign of serious illness.  For example, while often people with headaches worry about having a brain tumor, that’s pretty unlikely.

Nevertheless, it’s important to recognize when a headache is more than “just a headache.”  Doctors look for certain collections of signs and symptoms to put them on the alert for serious causes of headaches.

None of these are absolute guarantees of a serious cause to a headache, but they are signs that should not be ignored, and in fact may require immediate and urgent investigation.  

1) A severe headache comes on very suddenly.

From the beginning of their medical training, doctors learn to beware a sudden “thunderclap” headache, classically described as “the worst headache of my life.”  The fear is of a subarachnoid hemorrhage—blood that erupts into the space between the brain and the membranes next to the inside of the skull.  This may result from trauma or sometimes a vascular malformation like an aneurysm, a bulge the wall of a blood vessel that can suddenly rupture, leading to significant bleeding which can sometimes be life threatening. 

2) The headache is associated with confusion or a change in consciousness.

The causes of headache associated with confusion are numerous, and few of them can be ignored.

  Seizure, stroke, infection and more can all lead to this one tell tale sign of badness in the brain. 

3) The headache follows an injury to the head.

The problem with this sign is that it seems obvious—of course you have a headache—you just hit your head, after all!  But it’s critical not to overlook serious consequences of traumatic brain injury, or to underestimate the potential for ongoing symptoms.

  For example, an epidural hematoma is a collection of blood in the skull that usually occurs due to head trauma.  Sometimes these injuries are followed by a deceptive “lucid interval” during which the victim seems to be normal, with the exception perhaps of a nagging headache.  By the time more obviously concerning symptoms become apparent, it can be too late.

4) A severe headache comes along with severe nausea or vomiting. 

While some nausea and vomiting with headache may be due to a viral illness, it can also be a sign of increased intracranial pressure.  The skull is only so big, and if the brain swells due to infection, tumor, or inflammation, the brain will have to do some unnatural contortions to stay within its tiny home.  In the worst case scenario, the brain may herniate, meaning that part of the brain shifts through one of the skull’s few natural openings, such as where the spinal cord exits.  The result can be significant damage to parts of the nervous system essential for any kind of meaningful life.

  Other potentially worrying signs of high intracranial pressure include headaches that are worse in the morning or that wake you from sleep, or  headaches that come on right after vigorous activity.

5) The headache is associated with changes in vision.

Changes in vision can sometimes result from a relatively harmless (albeit painful) process such as migraine, but sometimes signify something more serious.  Elevated intracranial pressure can lead to blurry vision and headache, as can significantly high blood pressure.  Sometimes vision loss can occur in the setting of a disease such as temporal arteritis, an inflammation of the blood vessels to the brain, which can lead to permanent vision loss and strokes.   Or the problem can be in the eye itself, as in the case of closed angle glaucoma, a medical emergency.  

6) The headache is accompanied by other symptoms like weakness, numbness, seizures, changes in personality, or speech difficulties.

All of these symptoms can result from part of the brain being damaged, whether by stroke, infection, or a tumor.  Even without a headache, these symptoms maybe serious enough to merit immediate medical attention, especially if they come on quickly and without easy explanation. 

7) New and regular headaches develop after the age of 50.

As the saying goes, getting old isn’t for wimps. Other causes of headache, such as migraine, less commonly come on after middle age, but risks for more serious causes, such as temporal arteritis or tumors, increase as we get older. 

8) A headache that is associated with fever, stiff neck, or rash. 

Meningitis is an inflammation of the tissues around the brain, and can be a medical emergency.  While some of these signs may be attributable to other illnesses, such as the flu, they shouldn’t be taken lightly, especially in combination with other neurological problems, confusion or signs of high intracranial pressure.

9) You have a known medical condition that can contribute to serious causes of headaches. 

If you have high blood pressure and it’s not well controlled, your headache could be a hypertensive emergency.  A history of cancer raises the risks of a headache being due to metastatic disease.  Poor health habits like smoking can raise the chances of stroke.  While it’s no guarantee of a serious cause to a headache, it’s important your doctor know as much as possible about your past health history. 

10)  You’ve never had significant headaches before, or this headache is very different than previous headaches.

Neurologists have been taught to fear change, at least in their patients.  While it’s not that uncommon for something like migraine to change over time, new symptoms deserve some consideration.

The bottom line is that while most of the time a headache has less serious causes, such as migraine or tension, it’s important to ensure that certain headaches aren’t due to a more dangerous illness.  If a headache is new in severity or quantity, if it comes on suddenly, if it is accompanied by other neurological symptoms, or if you have increased risk of serious medical problems, the headache deserves to be evaluated as soon as possible. 


Ropper AH, Samuels MA. Chapter 41. Diseases of the Nervous System Caused by Nutritional Deficiency. In: Ropper AH, Samuels MA, eds. Adams and Victor's Principles of Neurology. 9th ed. New York: McGraw-Hill; 2009

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