A headache refers to a sensation of pain occurring in any part of the head. The most commonly affected regions of the head are the forehead, the temples, and the back of the head. Sometimes, a headache does not have a specific location, and may be felt throughout the skull. Apart from location, headaches also differ in other characteristics – type of pain, intensity of pain, and duration of pain. Most commonly, headaches are described as feelings of dull pain, throbbing pain, shooting pain or pressure sensation. The pain may either be mild, moderate or severe. It may either last for a few hours or for a few days. It may be a one-time event. Alternatively, it may come back intermittently.
Sometimes a severe headache can occur suddenly. The nature and location of the severe headache varies according to the cause. A severe headache, or a rapidly worsening headache that occurs suddenly could be a sign of some serious underlying condition that needs urgent treatment. It may even be the sign of a life-threatening condition. Therefore, sudden severe headaches should be taken seriously and medical attention must be sought as soon as possible.
Read more on headache location.
Causes of Sudden Severe Headaches
There are myriad causes of sudden severe headaches. The headache may be only one of many symptoms present and often diagnostic investigations are necessary to confirm the exact cause.
Diseases caused by insect bites
Sudden severe headaches are one of the symptoms in diseases caused by certain insect-bites. Examples of such insect-borne diseases include malaria, dengue, African sleeping sickness (trypanosomiasis), typhus, tick fever, and poliomyelitis. Other associated symptoms may include fever (which may be high), vomiting, rashes, fatigue, muscular pain across the body, and sore throat.
Meningitis and encephalitis
Severe headache that starts from the back of the head and is accompanied by stiffness in the neck is a common symptom of meningitis and encephalitis. Meningitis and encephalitis can be caused by exposure to certain bacteria, viruses, fungi or chemicals. Other accompanying symptoms include high fever, nausea, vomiting, back pain, leg pain, and sensitivity to light (photophobia).
Read more on meningitis.
Lyme disease or borelliosis is caused by an untreated tick bite. The symptoms of sudden severe headache, stiff neck, knee arthritis, muscle weakness, numbness, paralysis of facial muscles, heart palpitations, visual problems, and memory problems may arise weeks (and even years in some cases) after the initial tick bite.
Glaucoma causes an increase in pressure within the eyes, resulting in sudden and severe pain in the region around eyes, blurred vision, redness and nausea. It can be triggered by stress, infections, antihistamine medications, certain injuries and surgeries.
A stroke may, in rare cases, be associated with sudden headache. The headache in stroke is usually restricted to one side of the head. However, many stroke patients do not report a headache prior or during a stroke.
Ruptured brain artery aneurysm
Rupture of a brain artery (a result of aneurysm) is characterized by a sudden severe “thunderclap” headache. This headache is accompanied by bleeding in the subarachnoid space in the skull (the space between the brain and its membranous cover), nausea, vomiting, neck stiffness and back pain. Loss of consciousness may also occur in some cases.
Idiopathic intracranial hypertension
Recurrent, throbbing, severe headaches that last for hours may occur in young and obese women. The cause is not known since no head abnormalities can be detected with CT scans or MRI.
Sinusitis (inflammation of the sinuses) is frequently associated with severe headaches that feel like intense pressure in the head. These headaches are associated with tenderness in cheeks and forehead, blocked nose, sore throat, and mild fever. Pain may also be felt in the teeth and in the back of the head. Sinusitis is caused by allergies and infections with bacteria, viruses, and fungi.
Excessive alcohol consumption
Hangovers, resulting from excessive alcohol consumption, are associated with intense and throbbing headaches. Other characteristic features include tiredness, dizziness, nausea, loss of appetite and sensitivity to light.
Severe headaches may occur within a few minutes to a few hours after food poisoning. These headaches are accompanied by vomiting, diarrhea, and abdominal cramps. In some cases, itch, numbness, paralysis, and confusion may also occur.
Severe headache is also a symptom of water-borne infections such as leptospirosis. Leptospirosis is caused by drinking water that is contaminated with animal urine. High fever, muscle aches, red eyes, and jaundice are other features of the disease.
Severe headache associated with the use of illicit recreational drugs such as cocaine, heroin, ecstasy, and speed (amphetamines), could be a sign of intracranial hemorrhage (bleeding inside the brain). Other accompanying signs and symptoms include confusion, nausea, shallow breathing, and constricted or dilated pupils.
Poisoning with carbon monoxide (CO), poisonous mushrooms, and poisonous plants such as the lily of the valley and the foxglove, is associated with severe headache, nausea, fatigue, chest pain, reddish skin, confusion, and hallucinations. Loss of consciousness and death may also occur.
Severe headaches may also arise due to overdose, withdrawal, and side-effects of certain medications. Examples include nitroglycerin, opiates (morphine, codeine), aspirin and high doses of vitamin A.
Severe headaches, especially in the morning, are characteristic of low blood sugar (hypoglycemia). Hypoglycemia is a common condition in diabetics but can also occur even without diabetes, as is the case with the use of certain medication, strict dieting and prolonged fasting.
Blunt trauma to head
Head injury due to blunt force trauma directly causes severe headaches. This may be seen with a blow to the head as a result of a fall, assault, contact sports or motor vehicle collision. These severe headaches may last from a few hours to many days.
A lumbar puncture can produce severe throbbing headaches in some people. It is a diagnostic investigation done to collect a sample of cerebrospinal fluid (CSF), especially when conditions like meningitis issuspected. These headaches may start within a few hours of the procedure and can last for days.
Severe headaches rarely occur with high blood pressure. When they do occur (for example, in case of adrenal tumors), both the sides and the back of the head may be involved. The headaches are of the throbbing type.
Injury to vertebral artery
“Thunderclap” headaches and other neurological problems could occur if the vertebral artery is injured. This may happen in sports injuries.
Severe headache is also associated with brain abscess, or collection of pus in a region of the brain. This mostly happens in patients with a weakened immune system or congenital heart disease.
High altitude sickness
Symptoms of high altitude sickness, including sudden and intense throbbing headaches, may appear within 6 hours to 4 days after climbing a high mountain.
Severe throbbing headache is also a feature of eclampsia, or seizures occurring in some pregnant women.
Migraine is characterized by a one-sided throbbing headache that intensifies with physical exertion. Migraines can be triggered by monosodium glutamate (MSG), red wine, cheese, and strong fragrances.
Severe recurrent headaches are also a feature of increased carbon dioxide levels in the blood.