Almost everyone experiences a headache now and then. This common symptom can range from mild to severe, though most last less than 24 hours. Many common causes of headaches are minor and will go away on their own or with a dose of an over-the-counter painkiller. In rarer instances, a headache can be a sign of something more serious.

Eye Strain

Especially with the increase in time spent on computers these days, eye strain is a common cause of headaches. Strain is placed on the eyes from staring at a computer screen for long periods, reading in poor light, or any other situation where your eyes must work harder than usual due to lighting that is not optimal.

Headaches from eye strain do not necessarily mean that there is anything wrong with your eyes. While you can't avoid the need to look at your computer screen for work, you can minimize headaches from eye strain by ensuring your eyes are rested and relaxed at regular intervals throughout the day and as much as possible when you're not working. Make sure to have sufficiently bright lighting when reading or doing other close-up work, particularly if you wear glasses.

woman in front of laptop computer rubbing sore eyes


Muscle Tension

Tight, stiff, or strained muscles can lead to tension headaches. This is especially true for people who have a job that requires them to sit in the same position for long periods, as well as those who experience a lot of anxiety and stress.

Usually, it's tension in the muscles of the head, jaw, neck, or upper shoulders that lead to this kind of headache. Getting massages or taking a regular yoga class are great ways to reduce chronic tension headaches, but using a heating pad, stretching at home, or massaging the areas yourself or with a foam roller can help with this too. As with eye strain, make sure to take breaks during sedentary work days to move any tense muscles.

woman sitting at a desk stretching sore back and neck


Bright Lights

Bright lights can cause headaches for reasons similar to too little light: the eyes are forced to adjust to brightness levels that are not optimal for them. Some people who are particularly affected by bright lights find they even trigger migraines.

Not surprisingly, removing the trigger is the best way to ease a headache caused by bright lights. Go into a dark room or cover the face and let the eyes relax. OTC medications can also help alleviate the headache more quickly.

woman in bright room rubbing eyes from headache



Dehydration is another common cause of headaches—in fact, the head pain during a hangover is mostly due to this factor. Often, this kind of headache causes a pulsing sensation in the temples. To prevent them, aim to drink water regularly throughout the day.

Don't wait until you are thirsty; the body is already dehydrated at this point. Most people should drink around two liters of water a day. Increase this if it's hot outside or you've been exercising. In many cases, headaches caused by dehydration will start to go away once you've corrected this imbalance in your body.

man on his couch with glass of water headache dehydration


Cold or Flu

Sinus headaches occur when the sinuses—hollow cavities that run throughout the head—are swollen, irritated, or inflamed. Allergies and cold and flu viruses can impact the sinuses and cause these headaches, as well as infections like sinusitis.

Headaches caused by a virus can be painful and debilitating—especially if you’re already suffering from other cold and flu symptoms—but they can usually be treated with over-the-counter medication, such as decongestants and analgesics.

woman with cold or flu headache


Food Additives

Many people report developing headaches after eating certain foods. In some cases, it's the additives and artificial chemicals that add flavor and preserve foods that cause this symptom; some people seem to be more sensitive to these than others.

If you find certain foods trigger your headaches, it may help to keep a diary of what you're eating and when the headaches occur. Research the foods that seem linked to the symptom and see if they contain nitrites, sulfates, or one of the many other additives that have been linked to headaches. You may need to find alternatives to these foods.

plate of food additives with labels



Although some people find caffeine can help relieve their headaches, too much can also cause them, not to mention nausea, vomiting, dizziness, weakness, and even abnormal heart rhythms.

The amount of caffeine that causes headaches varies from person to person—some people may be able to tolerate more than others without experiencing side effects. But as a general rule of thumb, 300 milligrams (mg) per day is enough to cause symptoms in some people; this is about 4 cups.

Alternatively, suddenly stopping caffeine can cause withdrawal headaches if you are a regular caffeine drinker, so if you're planning to cut back, you may want to slowly reduce your consumption. Try swapping it out for decaf coffee or tasty teas, which generally have 50% or less caffeine than coffee.

hand holding coffee cup with empty coffee cups stacked


Hormone Changes

Hormones are chemicals produced by the body that regulate growth, development, and reproduction. A sharp rise or drop in one of these hormones can cause headaches.

This is particularly common for women before menstruation and during ovulation, as the hormone estrogen drops. Menstrual headaches rarely last more than a day and can be managed using over-the-counter remedies.

pregnant woman on couch with a headache


Brain Aneurysm

Most headaches are caused by one of the factors outlined previously. In some rare cases, though, headaches are symptoms of serious conditions. If a headache comes on suddenly and is blindingly painful, it could be caused by a brain aneurysm. This symptom has been described as "the worst headache imaginable," so it should be easy to distinguish from a regular headache. If you develop a sudden, extremely painful headache, it is crucial to seek immediate medical attention, as a brain aneurysm is life-threatening.

doctor looking at blood flow to the brain on monitor


Brain Tumor

In extremely rare cases, constant headaches are a symptom of a serious disease, such as a brain tumor. If you experience chronic headaches, along with nausea, vomiting, or weakness in your arms or legs, visit a doctor to investigate the cause.

Brain tumors can also cause seizures. If other symptoms accompany your persistent headaches, it is best to seek medical advice to rule out any sinister cause. Keep in mind, however, that brain tumors are rare and not a common cause of headaches.

doctor pointing to scans of a patient's brain


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