Headaches occur commonly for most people, but the sudden onset of a new and severe headache can indicate many serious conditions and should receive medical attention immediately. Those who have frequent headaches, such as migraine sufferers, will usually recognize their normal pattern of pain. According to the Foundation for Education and Research in Neurological Emergencies (FERNE), only one to 5 percent of patients who enter an emergency room complaining of headache have a serious underlying condition, but some of these conditions can prove life threatening.
Stroke
A stroke is defined by interruption of blood flow to the brain, either by a ruptured blood vessel, or by a blood clot. According to FERNE, patients describing their headache as "worse than any headache they have ever had," present a classic sign of bleeding in the subarachnoid space of the brain. Immediate treatment becomes critical for stroke victims as it usually proves much more effective if delivered within three hours. Additional signs of a stroke include weakness or numbness, particularly on one side of the body, slurred speech and difficulty with motor movements.
Medication
Many prescription or over-the-counter medications and even vitamins have the potential of causing a severe headache. According to healthype.com, nitroglycerin, opiates, aspirin and intravenous vitamin A all can potentially cause a sudden severe headache when taken in overdose amounts. It is important to ensure that your doctor knows of all medications including vitamins that you have taken.
Bacterial Meningitis
Sudden onset of a severe headache can result from bacterial meningitis and should be suspected if accompanied by fever. Meningitis is an infection of the coverings of the brain and spinal cord, called meninges, or of the fluid that surrounds them. Patients with meningitis often have neck and head pain that becomes aggravated by bending the head forward, high fever, nausea and vomiting and sensitivity to light, according to Mayo Clinic.
Carbon Monoxide
The Mayo Clinic reports that carbon monoxide poisoning remains a leading cause of death from unintentional poisoning. In addition to a severe headache, other symptoms include confusion, irritability, dizziness, nausea and a rosy flushed appearance. Carbon monoxide has a greater affinity for hemoglobin than oxygen does and makes it impossible for your blood to carry appropriate amounts of oxygen to the brain and other tissues.
Glaucoma
Glaucoma is a condition characterized by very high pressure within the eye which can lead to optic nerve damage, blindness and a severe sudden headache. This pressure can result from stress, antihistamines, infection, injury or surgery, according to healthhype.com. Additional symptoms that may occur with the headache include nausea, blurred vision and eye redness.
Idiopathic
Occasionally an individual will present to their doctor or an emergency room complaining of a sudden severe headache and CT or MRI of the head reveals nothing abnormal. This is referred to as idiopathic intracranial hypertension and according to healthhype.com, it occurs most often in young obese women.
