Headaches 101

This pained expression isn't uncommon for headache sufferers.
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It often begins so innocently -- just a vague sensation of slight pressure around your temples. But soon it intensifies. Before long, it feels as if your head is being squeezed like a stress ball. The pain makes it difficult to focus and starts to affect your mood as well. Only after several hours (and a few pills) does the headache finally subside.

The scenario just described is all too common for the many people who deal with tension headaches. And those who only get this type of headache are the lucky ones. Imagine, for example, the experience of a migraine headache. Strange distortions to your vision might come first as a warning sign, and then the full attack commences. Once the throbbing head pain and nausea are in full swing, resting in a dark room is all you'll feel like doing.


The pain of cluster headaches is even more intense, commonly described as the feeling of a hot poker being stuck into the brain through one's eye socket. Cluster headaches get their name because they come in repeated bursts, with each burst being so excruciating that unlucky victims can often do nothing but pace around in agony.

As opposed to primary headaches, such as the types of headache described above, secondary headaches arise from an underlying injury or illness. For example, a blow to the head can cause internal bleeding that increases pressure within the brain, creating an intense headache. Because secondary headaches can indicate a serious underlying problem, they should never be ignored

So how do you know when it's time to see the doctor about a headache, and what are the different types of headaches it might be? Also, why do headaches hurt in the first place, and how can they be treated?

Let's start on the next page by taking a closer look some of the major headache types.


Tension Headaches and Migraines

Fatigue causing your headaches? Or is it poor posture?
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The experience of a tension headache, described on the previous page, will be suffered by an estimated 90 percent of Americans during their lifetime. These headaches often feel like pressure is being applied uniformly around the head, or as if the head is being steadily squeezed in a vise. Lasting anywhere from 4 to 72 hours, tension headaches are the most common, but fortunately the least severe, of all headaches types.

Tension headaches can be further classified as episodic or chronic. Episodic tension headaches come and go sporadically, often during times of temporary fatigue, stress or anxiety. Over-the-counter medications and rest are generally effective at relieving episodic tension headaches.


Chronic tension headaches occur regularly, sometimes every day, for weeks to months at a time. Often, it's not simply stress or fatigue that causes chronic tension headaches, but physical or psychological problems. For example, a contributing factor could be constantly strained or stretched muscles, resulting from poor posture, eyestrain or a misaligned bite. Arthritis, joint disorders and depression are other common causes of chronic tension headaches. Untold numbers of people shrug off the pain of chronic headaches when a simple trip to the doctor could reveal the problem behind all the pain.

Around 30 million Americans experience the more intense migraine headaches, which can last for days and be painful to the point of preventing the victim from functioning. Migraine headaches have many unique symptoms that set them apart from tension headaches. For example, migraines are often described as a throbbing pain that begins on one side of the head and then spreads out. Migraines can also come with an increased sensitivity to light and worsen with physical exertion. As a result, migraine sufferers often choose to lie down in the dark in an attempt to reduce their pain.

Another characteristic of a migraine is that it's often accompanied by gastrointestinal disturbances, including abdominal pains. This symptom results from stimulation of the sympathetic nervous system, which is normally activated in response to stress or pain. The digestive system disturbances caused by migraines slow the uptake of ingested medications and reduces their effectiveness.

Migraines are also unique because they're often preceded by warning signs, which might include fatigue, depression, euphoria or even cravings for certain types of foods. For about 20 percent of migraine victims, the onset of an attack is signaled by an aura, which can manifest as an abnormal disturbance to any one of the five senses. Visual auras are by far the most common, and often take the form of wavy lines or flashing lights. (For the full story on migraines, check out How Migraines Work.)


Cluster Headaches and Secondary Headaches

The intense pain behind your eye? That's a cluster headache.
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One of the most intense types of headaches is a cluster headache. The pain is usually localized to one side of the head, generally behind one­ eye, which often becomes bloodshot as it tears up and swells. Sometimes the drooping of one eyelid or a reddening eye can indicate the onset of an attack.

Cluster headaches get their name because they can come in repeated bursts, with each burst lasting 15 minutes to three hours. These bursts of pain can appear and disappear, all without warning, in a cycle that continues for days, weeks or months. Sometimes the headaches then stop abruptly for many months, only to start up again during the same season of the following year. Thankfully, only about one in a thousand people has to deal with the experience of cluster headaches.


Tension, migraine and cluster headaches are the three most common types of primary headaches, but countless others exist as well. In total, more than 150 types of headache are categorized by the International Headache Society. Here are a few examples:

  • Exertion or exercise headaches typically appear during or after physical activity, and are linked to the widening of blood vessels required to deliver increased amounts of oxygen to the muscles.
  • Mixed headaches come with symptoms of both tension and migraine headaches. To treat mixed headaches, a combination of tension and migraine treatments must be carefully balanced.
  • Ice cream headaches, also called "brain freeze," occurs when cold foods pressing on the roof of your mouth trigger overlying nerves to quickly widen blood vessels and increase blood flow -- possibly in an attempt to warm up the head as a response to the cold.
  • Migraine equivalents are perceived as pain coming from somewhere besides the head. The most common type is an abdominal migraine, which can result in abdominal pain and vomiting, but no head pain.
  • Hemiplegic migraine is a rare type of migraine that can cause temporary motor paralysis and sensory deficits on one side of the body, followed by a very severe headache.
  • Chronic daily headache (CDH) sufferers experience headaches more than 15 days per month. There are several different types of CDH, including chronic migraines, chronic tension headaches and chronic cluster headaches.

Secondary headaches, in contrast to primary headaches, arise from an underlying injury or illness. They're uncommon but often very serious. There are many possible causes of secondary headaches, including brain tumors, strokes and infections. A sinus infection is one example of a common cause for a secondary headache. In this case, swelling, increased pressure and inflammation in the sinus cavity causes severe, localized pain. Migraines are commonly misdiagnosed as sinus headaches due to similar symptoms. Secondary headaches can indicate the presence of a serious issue that requires immediate medical treatment.

If you experience headaches that are severe, recurring or accompanied by unusual symptoms, it's smart to consult your primary care physician. He or she might ask a series of questions about risk factors and family history, perform a physical exam and run relevant diagnostic tests. Based on the findings of the examination, the physician may recommend lifestyle changes, prescribe drugs or refer you to a headache specialist. Unfortunately, distinguishing between different types of headaches isn't always easy. For example, there aren't even definitive tests able to confirm or rule out the presence of many headache types.

OK, so we've briefly covered some of the major types of headaches, but what causes them? And why are they so painful?


Headache Causes

You can thank your nerves for the pounding pain in your skull.
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Neither your brain tissue nor the bones of your skull contain pain-sensitive nerve endings, so what is the source of painful headaches? The answer has to do with the parts of your head that do have nerve endings. For example, the network of blood vessels that supply the base and surface of your brain are wrapped with sensitive nerve fibers able to fire off pain signals with a hair trigger. Pain-sensitive nerves can also be found in the scalp and in the muscles of your head, among other places.

Stress, muscular tension, inflammation and the constriction or dilation of blood vessels can all trigger the pain-sensitive endings of these nerves to transmit signals that activate the pain centers in your brain. Tension headaches, for example, can be caused by the chronic stretching of muscles that become tensed with stress or prolonged strain. One source of prolonged muscle tension is eyestrain -- a common cause of headache.


As with so many brain-related issues, doctors and scientists haven't fully uncovered all of the precise mechanisms and underlying causes of each type of headache. However, the experts have uncovered and explored many of the typical pathways involved in certain types of headaches. For example, migraine headaches are linked to changes in the flow of blood through vessels in the brain. As part of the migraine process, certain patterns of brain activity are believed to trigger the constriction of blood vessels, reducing the brain's oxygen supply. As part of a chain reaction, the blood vessels then dilate (widen) in response, and certain chemicals known to cause inflammation are released. The nerves coiled around the blood vessels then shoot off throbbing pain signals that pulse along with the blood flow. Some experts have suggested that in people prone to migraines, these blood vessels are overly reactive to certain conditions.

­While the precise biological mechanisms that cause headaches aren't fully understood, many common triggers, or factors that can lead to headaches, are associated with different headache types. For example, stress is the most commonly identified trigger for migraine headaches. Changes in hormone levels within the body are another known trigger, which is why three times more women than men experience migraines.

Experts know even less about the root cause of cluster headaches. Much of what is known about cluster headaches has to do with the common triggers. For example, alcohol (especially red wine) and cigarette smoke are two common factors that contribute to cluster headaches in an unknown way.

­­Because cluster headaches often occur around the same time each day, or during the same season each year, experts do know that cluster headaches are somehow related to the body's natural sleep/wake cycle and with seasonal changes. There's evidence that the hypothalamus, a part of your brain that acts as an internal biological clock of sorts, is involved in the onset of cluster headaches. Unlike tension headaches and migraines, cluster headaches are more common in men. The reason for this is unknown, but could be partially due to a higher link between males and certain risk factors, such as alcohol, smoking and physical exertion.

So we've taken a look at what causes the pain of headaches. Now how do you get rid of it?­


How to Get Rid of Headaches: Drug Treatments

Take two and call us in the morning.
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So what kinds of drugs are helpful for treating headaches, and how do they work? First off, there are two major approaches for treating a headache with drugs. Acute, or abortive, treatments are designed to treat a headache once it begins. However, when a person suffers from frequent headaches that don't respond well to acute treatments, it's worthwhile to consider a regular dosage schedule with preventative drugs, which can help keep headaches from occurring in the first place.

Acute drugs, designed to stop headaches, should be the first treatment approach. For milder headaches, or headaches in their early stages, over-the-counter analgesic drugs are often effective for this purpose. Common examples include acetaminophen (Tylenol) and nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen. Over-the-counter analgesics work by acting on pain centers in the brain or by reducing inflammation around pain-sensitive nerves.


Some common analgesic drugs contain caffeine, which can help to treat headaches by speeding the uptake of medications into the bloodstream. Because caffeine is a stimulant that can alter blood flow within the brain, shifting caffeine levels can also be the cause of headaches. For example, if you try to quit a caffeine addiction cold turkey, you'll be taking away a brain-altering drug that your body was used to having around. Removing it can shift the balance of other chemicals in your brain and lead to withdrawal symptoms -- including major headaches.

­Other acute treatments are designed to act directly on parts of the pathways known to be involved in headaches. For example, drugs classified as triptans or ergotamines are used to combat migraines by constricting dilated blood vessels and adjusting the balance of certain chemicals in the brain. To speed delivery into the blood stream, acute treatments are often given as nasal sprays or are sometimes injectable. In the case of migraines, these non-oral delivery methods are important, since the digestive disturbances associated with migraines can interfere with the uptake of ingested drugs. Quick delivery is also important for cluster headaches, which can come on quickly without warning.

Acute treatments for cluster headaches can be similar to the treatments for migraines, although sometimes pure oxygen breathed through a mask or numbing nasal sprays, such as lidocaine, can offer relief. When normal acute drug treatments aren't enough to relieve the pain of a severe headache, a doctor might prescribe stronger narcotic drugs. However, because these types of drugs are habit-forming, health professionals avoid prescribing them when possible.

Patients who experience headaches on a frequent basis sometimes benefit from preventative drug treatments, designed to reduce the chance that a headache will ever start. For example, four drugs approved by the FDA for migraine prevention have been in widespread use for many years. When conventional preventative drug treatments are ineffective for reducing headache frequency, certain antidepressant drugs might be prescribed as an alternative. These are thought to work by affecting the balance of serotonin, a chemical in the brain often involved in the development of headaches due to its effects on blood vessels. Preventative treatments are seldom perfect, though, so it's important to have acute treatments ready as a backup.

Are drugs the only way to treat headaches? We'll look at alternative options on the next page.


How to Prevent Headaches

Want to avoid a headache? Get your schedule straight and take care of your stress.
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A wide range of non-drug-based treatments and therapies can also be used to relieve or prevent headaches.

One of the most straightforward ways of preventing headaches is to avoid the triggers that cause them. Because stress is one of the most commonly reported triggers for migraine headaches, a good first line of defense for migraine sufferers is to reduce it by managing their daily schedules. Physical and mental stress can result from changing up your normal routine, so one way to lower stress levels is to keep your daily schedule of sleeping, exercising or eating meals constant.


­Other triggers might not be so easy to pick out. Certain foods and drinks, weather patterns and hormonal changes are just a few of the physical and environmental factors that can contribute to certain types of headaches. Because it can be difficult to identify the specific culprit in any one case, some sufferers find it worthwhile to keep a detailed log, called a headache diary. In this log, a person carefully records details about each headache he or she experiences and lists all notable conditions and factors surrounding it. By comparing the common factors that recur around most headaches, major triggers can often be identified and then avoided in the future.

Another way to lower stress levels and combat headaches is relaxation training. Here, the patient learns specific techniques that can be used to relax his or her body and mind. The next step from there might be biofeedback treatments, in which specialized equipment allows the patient to learn how to enhance his or her control over certain bodily responses related to stress. For example, the equipment might monitor heart rate, body temperature or tension in certain muscles, allowing the patient to learn what patterns of thoughts or activities can affect and control these responses. Once the patient learns how to attain better control of these stress-related responses, the equipment is no longer needed.

Other less conventional treatments might include herbal therapies or acupressure or acupuncture treatments. An individual seeking these types of alternative therapies should be sure to rely on a specialist with the proper training and credentials.

As doctors, scientists and engineers continue to learn about the brain and nervous system, more effective methods of combating headache will be developed. For example, specialized drug treatments might one day be custom designed to best treat each individual patient, based upon his or her specific condition and bodily makeup. As another example, a technique called deep brain stimulation is already used to treat certain brain disorders by stimulating specific areas of the brain with tiny pulses of electricity. In exploratory experiments, deep brain stimulation has been used to effectively control headaches that were otherwise untreatable.

For all things headache- and pain-related, try the articles listed on the next page.


Lots More Information

Related HowStuff Works Articles
More Great Links

  • "Headache." Neurology Channel. Jan. 01, 2002. (Aug. 21, 2008) http://www.neurologychannel.com/headache/index.shtml
  • "Headache Education." National Headache Foundation. (Aug. 21, 2008) http://www.headaches.org/education
  • Lee, Dennis. "Headache." MedicineNet.com. March 23, 2007. (Aug. 21, 2008) http://www.medicinenet.com/headache/article.html
  • "Headaches." YourTotalHealth. Jan. 19, 2007. (Aug. 21, 2008) http://yourtotalhealth.ivillage.com/headaches.html
  • "What is a Cluster Headache (CH)?" Organization for Understanding Cluster Headaches. Jan. 01, 2002. (Aug. 21, 2008) http://ouch-os.org/index.shtml
  • "Headache: Hope Through Research." National Institute of Neurological Disorders and Stroke. (Aug. 21, 2008) http://www.ninds.nih.gov/disorders/headache/detail_headache.htm
  • "Headaches in Children." American Headache Society. (Aug. 21, 2008) http://www.achenet.org/education/patients/HeadachesInChildren.asp
  • Preidt, Robert. "Deep brain stimulation aids those with rare headache condition." MedicineNet.com. April 17, 2007. (Sept. 06, 2008) http://www.medicinenet.com/script/main/art.asp?articlekey=88797
  • "Fast Facts about Headaches." The National Pain Foundation. March 27, 2008. (Sept. 6, 2008). http://www.nationalpainfoundation.org/MyTreatment/articles/Headache_FastFacts.asp
  • "Mechanisms of Cluster Headaches." Cluster Busters. (Sept. 08. 2008). http://www.clusterbusters.com/mechanisms.html
  • "The complete guide to headache." The National Headache Foundation. (Sept. 08, 2008). http://www.headaches.org/educational_modules/completeguide/tension3.html
  • "Migraine FAQs: An interview with a Mayo Clinic Specialist." MayoClinic.com. Feb. 19, 2008. (Aug. 21, 2008) http://www.mayoclinic.com/health/migraine-headache/MI00026