Headaches Explained: Causes, Symptoms, And Treatments

Almost everyone gets headaches now and then, but for some, the frequency or severity of their headaches can be debilitating and might constitute a disorder. As the World Health Organization (WHO) explained, headache disorders can cause "substantial personal suffering, impaired quality of life and high financial cost." Tension-type headaches and migraines are the most common of these headache disorders. Globally, about a third of men and half of women get tension-type headaches. Migraines impact about one in seven individuals worldwide.

While tension-type headaches and migraines may be the most prevalent, there are, according to the Cleveland Clinic, more than 150 distinct types of headache. They fall into two broad categories: primary and secondary (via the Mayo Clinic). Primary headaches aren't caused by another medical condition and are the result of "overactivity of or problems with pain-sensitive structures in your head." Chemical activity in the brain, the nerves or blood vessels surrounding the skull, or the muscles of the head and neck can all play a role in primary headaches. Genetic factors and lifestyle choices may also contribute to who gets primary headaches and when they occur. 

Secondary headaches, on the other hand, can be attributed to an underlying cause, such as alcohol, a concussion, or a brain tumor. The symptoms of a headache can give medical professionals important clues about its cause and guide treatment options.

Tension-type headaches

As the Cleveland Clinic explained, tension-type headaches, often referred to as tension headaches, are the most common type of headache. Tension-type headaches are classified based on how often an individual experiences them. Episodic tension-type headaches occur fewer than 15 days a month. An estimated two-thirds of adults get episodic tension-type headaches. Chronic tension-type headaches occur more than 15 days a month for at least three months in a row. Only about 3% of adults get chronic tension-type headaches.

The exact cause of tension-type headaches is unknown, although possible triggers include tightened muscles in the back of the head and neck, stress, sleep problems, and pain elsewhere in the head and neck, such as jaw pain. Although tension-type headaches aren't generally considered dangerous, in some cases they may be caused by an underlying medical condition that needs to be addressed, such as thyroid disease.

An individual tension-type headache can last anywhere from 30 minutes to months. Most episodic headaches last hours to no longer than a week. Compared to other types of headaches, tension-type headaches usually cause only mild to moderate pain and aren't usually accompanied by other symptoms such as nausea or vision changes. They're often described as something pressing on both sides of the head or a tight band constricting the head. In most cases, tension-type headaches can be treated with over-the-counter pain relievers such as aspirin, ibuprofen (Advil), naproxen (Aleve), or acetaminophen (Tylenol). The antidepressant amitriptyline (Elavil) also appears to help alleviate chronic tension-type headaches.

Migraine

According to the Cleveland Clinic, migraines affect approximately 12% of American adults, and women are three times as likely as men to experience them. There are many subtypes of migraines, but the most prevalent are migraine without aura (also known as a common migraine) and a migraine with aura (complicated migraine). About 15% to 20% of migraine sufferers experience aura. Migraines have four stages, although not everyone will experience all four. The prodrome phase lasts a few hours to a few days and can include difficulty concentrating or sleeping, irritability, and fatigue. 

The aura stage (if it occurs) lasts as short as five minutes and up to 60 minutes and can include vision changes and ringing in the ears. The aura sometimes happens with the headache itself. A migraine headache lasts four to 72 hours and is generally described as severe drilling or throbbing pain that starts on one side of the head and then spreads to the other. In addition, people often experience sensitivity to light, sound, or certain smells, nausea, sweating or chills, dizziness, and speech changes. Finally, the postdrome phase (also known as the migraine "hangover") lasts one to two days and is characterized by depression, difficulty concentrating or comprehending information, and fatigue. About 80% of people who get migraines experience the "hangover."

It's unclear what causes migraines, although many things, including stress and hormonal changes, can trigger them. Treatment options include medications to stop or shorten migraines once they've begun, as well as medications to minimize the chance of them happening in the first place.

Cluster headaches

According to the Cleveland Clinic, cluster headaches are generally considered to be the most severe type of headache an individual can experience. In fact, they're sometimes referred to as "suicide headaches" because people have taken their lives during or in anticipation of a cluster headache. Fortunately, they're rare, affecting only about one in every 1,000 people. Men and women are affected equally, and cluster headaches usually first appear between age 20 and 40.

Cluster headaches get their name from the (characteristic) grouped pattern they follow. During an attack, individuals can experience up to eight severe headaches a day, each lasting 15 minutes to three hours. This happens daily for weeks or months, and then the headaches go away for months or even years before reappearing. About 20% of cluster headache sufferers, however, have chronic cluster headaches that don't go into remission. The exact cause of cluster headaches is unknown, although a brain structure called the hypothalamus, as well as the trigeminal nerve, appear to be involved. 

The onset of cluster attacks often coincides with a change in seasons. Cluster headache pain is severe, described as burning or piercing, and one-sided. It's centered behind the eye but can spread to the forehead, temple, nose, and gums on the same side. People often feel like they can't sit still and need to pace. Medications or oxygen may help stop cluster headaches when they occur or shorten a cluster cycle, but cluster headaches can't be cured or prevented.

Caffeine withdrawal headaches

If you're a long-time coffee drinker who suddenly decides to switch to decaf, it's very likely that you'll experience withdrawal headaches. Caffeine is a vasoconstrictor, which means it causes blood vessels to narrow. In fact, according to a 2009 study published in Human Brain Mapping, blood flow to the brain is reduced by an average of 27% among moderate and heavy caffeine consumers. Over time, the body adapts to compensate for this reduction in blood flow. It does this mainly by increasing the number of adenosine receptors on blood vessel walls. 

Adenosine is a chemical byproduct produced by the normal functioning of the nervous system and it stimulates vasodilation (the enlargement of blood vessels). Caffeine closely resembles adenosine and can bind to adenosine receptors instead, crowding out the adenosine. The body makes more receptors so that the adenosine has somewhere to go and can combat the vasoconstrictive powers of caffeine.

When you suddenly stop consuming caffeine, however, this adaptive system quickly backfires. As the study explains, without caffeine molecules blocking some of the adenosine receptors, adenosine can bind to all of them. This causes an extreme widening of the blood vessels, substantially increasing blood flow to the brain. The rapid shift in blood flow is what causes the headaches commonly seen during caffeine withdrawal. The good news is that headaches and other caffeine withdrawal symptoms usually subside in two to nine days after quitting caffeine (per the Cleveland Clinic).

Rebound headaches

Ironically, overusing medication to treat headaches can actually cause more headaches, according to WebMD. Known as rebound headaches, they occur when the pain reliever you took for your initial headache wears off and your body has a withdrawal reaction, triggering another episode of pain and prompting you to reach for more medication. This can create a vicious cycle that's hard to break. 

Pain relievers that can lead to rebound headaches include aspirin, NSAIDs, acetaminophen (Tylenol), butalbital drugs (used to treat tension-type headaches), triptans (used to treat migraines), and ergotamine drugs (used to treat migraines and cluster headaches). Sedatives used as sleep aids, sinus decongestants, and prescription narcotics can also cause rebound headaches. Medications such as Excedrin that contain caffeine increases the likelihood of developing rebound headaches.

The best way to deal with rebound headaches is to prevent them from happening in the first place. It's important to only take pain relievers in the doses recommended by the manufacturer or your doctor. If possible, limit use of pain relievers to just once or twice a week. Avoid medications with caffeine. If you do find yourself in a cycle of rebound headaches, you'll need to either stop taking the medication that's triggering the headaches or gradually reduce the dose. Individuals whose rebound headaches are caused by sedatives or narcotics may need closer medical supervision as they wean off these drugs. Although coming off medication can temporarily increase headache frequency, this should resolve within a couple weeks.

Sinus headaches

If you've got a throbbing pain in your face, you may assume you have a sinus headache. But, according to the Cleveland Clinic, about 80% of headaches people believe are sinus headaches are actually migraines with nasal symptoms. True sinus headaches only occur because of a sinus infection, which causes pain and pressure in the sinuses. Sinus headaches, are, however, a very common symptom of sinus infections. Depending on which sinuses are infected, you may feel pain across your forehead, the bridge of your nose, or your cheekbones. 

Pain tends to get worse whenever you move your head suddenly. Other symptoms that can accompany a sinus infection include fever, nasal congestion, thick and discolored mucus, fullness in the ears, and a swollen face. Although migraine headaches can also include facial pain, nasal congestion, and a runny nose, secretions are clear rather than thick and discolored.

Sinus infections are caused by bacteria and viruses, and anything that causes mucus to build up in the sinuses can trigger a sinus infection by creating a perfect breeding ground for these germs. Common triggers of sinus infections include the common cold, seasonal allergies, a deviated septum, and nasal polyps. Treating a sinus headache involves resolving the underlying infection (usually with antibiotics if it's caused by bacteria). Warm compresses, saline nasal spray, and decongestants can also help mucus exit the sinuses and relieve the symptoms of a sinus headache.

Dehydration headaches

Dehydration is a common but completely preventable cause of headaches. According to Medical News Today, "When the body is dehydrated, the brain can temporarily contract from fluid loss. This causes the brain to pull away from the skull, causing pain and resulting in a dehydration headache." This pain can range from dull to intense and may be felt on the front, sides, back, or all over the head. Unlike with some other types of headaches, a dehydration headache is unlikely to cause facial or neck pain. 

It's usually accompanied with other signs of dehydration, such as extreme thirst, dark-colored urine, and dizziness. The key to treating a dehydration headache is restoring fluids and electrolytes, as well as avoiding heat, physical exertion, and substances like alcohol and caffeine that can increase dehydration.

It's important to note that hydration levels can also affect other types of headaches. For example, dehydration can be a common migraine trigger. In a study published in 2020 in the Journal of Clinical Neuroscience, researchers examined the hydration habits of 256 female migraine sufferers. They found a correlation between low water intake and frequent migraine attacks. They also noted that women who drank less water tended to have more severe and longer-lasting migraines than those who drank more water. A pilot study published in the European Journal of Neurology in 2005 found that participants who drank an extra 1.5 liters of water a day had shorter, less severe headaches.

Hangover headaches

Many of us have been there before: After a night of overindulging in alcohol, you wake up with a pounding hangover headache (probably also accompanied by other unpleasant hangover symptoms, such as nausea, dry mouth, and even diarrhea). According to Verywell Health, although hangover headaches are very common — also known as delayed alcohol-induced headaches — their exact cause remains unknown. Possible mechanisms for alcohol's ability to cause a headache include the direct effect of alcohol on the brain, the effect of acetaldehyde (a byproduct of alcohol metabolism) on the brain, dehydration, alcohol withdrawal, additives in alcohol, and alcohol's ability to impact hormone balance. 

Compounds called congeners in dark-colored alcohols such as whiskey and brandy can lead to more severe hangover headaches, and some people may be genetically predisposed to worse hangovers. Hangover headaches tend to occur on both sides of the head with pain that's localized in the forehead and/or temples, pulsates, and gets worse with physical activity.

Unfortunately, there's no miracle cure for a hangover headache. To make symptoms more bearable, however, individuals should focus on rehydrating and resting. Cold compresses and taking NSAIDs can also be helpful. It's important to avoid using acetaminophen (Tylenol), however, as it can cause liver damage when taken immediately before, during, or immediately after consuming alcohol (via Verywell Health). Most hangover headaches will last about 24 hours. To minimize the chance of a hangover headache, drink only in moderation and be sure to consume plenty of water alongside the booze.

Exertion headaches

According to the Cleveland Clinic, exertion headaches occur during or immediately after physical activity. Exertion headaches are also known as exercise-induced headaches because they're often triggered by exercise, particularly weightlifting and running. But any strenuous physical activity has the potential to trigger an exertion headache, including sex, a sneezing or coughing fit, or even straining hard to go to the bathroom. The mechanism behind exertion headaches is believed to be the rapid expansion of blood vessels. When doing something strenuous, the body's requirements for blood flow and oxygen increase, which causes veins and arteries to expand. 

But this dilation and increased blood volume can raise pressure inside the skull, leading to a headache. The pain of an exertion headache can be felt on one or both sides of the head and is often described as pulsating or throbbing. It may be accompanied by neck pain, nausea, sensitivity to light, and vision changes. Exertion headaches usually last a few minutes to a few hours, but may last up to a couple of days.

Exertion headaches can be treated like regular headaches. Over-the-counter or prescription-strength NSAIDs can reduce pain, or beta blockers may be prescribed for those who get frequent exertion headaches but can't take NSAIDs. Strategies for avoiding an exertion headache include avoiding the physical activity that triggers them (if possible), drinking plenty of fluids, and including proper warm-ups and cool-downs as part of your exercise regimen.

Hormonal headaches

You can add headaches to the list of unpleasant impacts hormone fluctuations can have on women. According to the Mayo Clinic, the drop in estrogen right before your period begins can trigger headaches, particularly migraines, in some women. These hormone-induced headaches can be treated the same way as other migraines, including NSAIDs, triptans (medications that block pain signals), ice, and relaxation exercises. Doctors may prescribe triptans and other medications for prevention of hormonal headaches. These medications can be taken several days before your period starts if your cycle is regular, or may need to be taken daily if it's irregular. Hormonal birth control reduces hormonal headaches for some women but increases their frequency for others.

Because estrogen levels increase at the beginning of pregnancy and remain high throughout gestation, pregnant women often see a substantial reduction in hormonal headaches. After delivery, however, estrogen levels drop, which, combined with all the stress and disruptions to normal sleep and eating routines a newborn can cause, may lead to a resurgence of hormonal headaches. During the years leading up to menopause (perimenopause), estrogen rises and falls unevenly, which can increase the frequency of hormonal headaches. Once menopause occurs and periods stop completely, many women experience fewer hormonal headaches, although they may see an increase in tension-type headaches. 

Hormone replacement therapy (synthetic estrogen) can improve hormonal headaches for some perimenopausal and menopausal women, worsen them for others, or have no impact.

Eye strain headaches

As Hackensack Meridian Health explained, eye strain can happen whenever you focus on something up close for a long time. In our technology-obsessed world, however, it's most likely to occur from staring at a computer or other screen for hours on end (known as digital eye strain). Eye strain can often cause headaches around and behind the eyes. In fact, an estimated 27% of individuals have experienced a headache because of digital eye strain. Digital eye strain can also include other symptoms like dry eye, blurry vision, pain in the neck and upper back, and irritability. 

Resting your eyes and focusing on something farther away can help alleviate the symptoms of an eye strain headache, but prevention is the best cure. Simple tweaks like keeping your computer screen at least 20 to 25 inches away from your face, removing glare on your screen, and ensuring that the ambient lighting in the room is as bright as the light from your screen can be helpful. Taking frequent breaks (short breaks every 20 to 30 minutes and a 20-minute break every two hours) and allowing your eyes to relax will also head off an eye strain headache before it starts.

But, according to Nvision, eye strain doesn't lead to headaches as often as many people think. However, Nvision also says, "Other types of eye problems — such as dry eye, injury to the eye, degenerative eye disease, uncorrected nearsightedness and farsightedness, and eye infection — can also cause headaches."

Concussion headaches

If you're unlucky enough to get a concussion (perhaps from a car accident or while playing sports), you're likely to experience a headache, according to Fraser Health. They can take several forms. Some people may experience a dull, constant pain at the base of their head that can spread across the top of the skull to the front. This type of headache is usually caused by irritation of a muscle in the neck. Others may have migraines or tension-type headaches. It's important to get plenty of rest after a concussion, which, along with medication, will help ease headache symptoms.

According to the Mayo Clinic, headaches are also a symptom of post-concussion syndrome (PCS). In PCS, symptoms experienced during the initial concussion last longer than is typical. Headaches and other PCS symptoms may persist for months or even years. Headaches can be either tension-type or migraines, although the former is more common and may be related to a neck injury sustained during the concussion. The other common symptoms of PCS include dizziness, fatigue, insomnia, irritability, ringing in the ears, difficulty concentrating, and blurry vision. 

Scientists are unclear as to why some people get headaches and other PCS symptoms. These lingering issues may be the result of structural brain damage or malfunctioning of normal nerve signaling, while others believe there's a psychological component. Concussion severity doesn't appear to affect the likelihood of PCS, and the only way to prevent PCS headaches is to avoid a concussion in the first place.

Thunderclap headaches

Although the pain they cause can be severe, most headaches aren't life or death situations. Thunderclap headaches, however, are an exception. As the Mayo Clinic explained, "Thunderclap headaches live up to their name, striking suddenly like a clap of thunder ... Thunderclap headaches are uncommon, but they can warn of potentially life-threatening conditions — usually having to do with bleeding in and around the brain." These conditions can include hemorrhagic stroke (rupture of a blood vessel in the brain), ischemic stroke (blockage of a blood vessel in the brain that cuts off blood supply), bleeding between the brain and the membrane covering the brain, hypertensive crisis (extreme elevation in blood pressure), leaking of cerebrospinal fluid (the liquid that surrounds your brain and spinal cord), and infection in and around the brain. 

In some cases, however, doctors can't determine a cause. Thunderclap headaches appear very quickly and cause severe pain that peaks within a minute. The pain may be accompanied by nausea, vomiting, fever, altered mental state, or seizures.

It's critical to seek immediate medical attention if you experience a thunderclap headache. Doctors may perform a variety of tests, including a CT scan or MRI of the head, mapping blood flow inside the brain (a procedure known as magnetic resonance angiography), or extracting and analyzing a small sample of cerebrospinal fluid for signs of bleeding or infection. While the thunderclap headache itself doesn't need to be treated, it's important to address its root cause as quickly as possible.

Headaches caused by brain tumors

When a severe headache hits, many people worry that it's a sign of a brain tumor. But, as Dr. Alan Carver, a neurologist at Memorial Sloan Kettering Cancer Center explained, this is rarely the case. For starters, brain tumors are very uncommon — each year, only five people out of 100,000 are diagnosed with one. Symptoms such as severe pain, nausea, and sensitivity to light may be very troubling, but statistically speaking they're much more likely to be signs of a migraine. In fact, the symptoms that are much more likely to indicate a brain tumor are neurological and include difficulty speaking, weakness on one side of the body, changes in vision, and seizures.

Neurologists can determine if a person's headache warrants further investigation into the possible presence of a brain tumor by examining a few key factors. Does the individual have any other symptoms that might indicate a brain tumor? Can the person pass a basic neurologic exam, or are there visible signs of impairment, such as dragging a leg or slurred speech? Has the headache built gradually or come on suddenly? How old is the individual? Because brain tumors are much more common in older adults. Does the individual have a past history of headaches?

And because the brain doesn't contain pain receptors, some brain tumors never cause headaches. A person will have a headache only if the tumor is large enough to press on surrounding nerves and blood vessels (via Johns Hopkins Medicine).