Migraines and tension headaches are the most common types of headaches. Healthcare providers believe that tense neck and shoulder muscles squeeze nearby blood vessels. This cuts off the supply of blood to the muscles of the face and scalp. Pain is felt in the muscles of the forehead and neck. The pain is often described as a tight band around the head. It is sometimes also felt in the jaw or neck muscles. Tension headaches may be occasional or daily. If you have daily headaches, it is important to get treatment to prevent them from becoming dependent on pain-relieving medicines and to prevent rebound headaches.

Call your doctor if you have any of the following:

• You need to take a pain reliever every day or almost every day
• You need to take more than the recommended doses of over-the-counter medicine to relieve headache symptoms
• You have a stiff neck, fever, or both along with the headache
• You have a headache plus shortness of breath, fever, or unexpected symptoms that affect your eyes, ears, nose, or throat
• You have dizziness, unsteadiness, slurred speech, weakness, or changes in sensation (numbness or tingling) in addition to a headache
• You feel confused or drowsy with a headache
• Your headaches begin after a minor injury, exercise or head injury
• Your headaches change in character
• You have persistent or severe vomiting with a headache
• Your headaches began after you became pregnant
• Your headaches began after age 40
• You have the worst headache of your life or a headache that comes on very quickly

Tension headaches are believed to be caused at least in part by tight muscles in the shoulders, neck, and head. Poor posture puts strain on muscles. Insomnia can cause headaches by increasing stress. Drinking too much caffeine or alcohol, and smoking can all trigger a tension headache. An uneven bite, clenching jaws, or grinding teeth can cause headaches by increasing tension in the jaw muscles.

If you take over-the-counter pain relievers, use the minimum dose and only when needed. Overusing pain medicines can cause a chronic daily headache called a rebound headache. Fasting is a common cause of headaches.

Getting too much caffeine and alcohol can trigger a migraine. Skipping meals or fasting can also trigger a headache. Other food triggers for migraines may include aged cheeses, peanut butter and nuts, and beans such as broad, pole, lima, pinto, and garbanzo.

There are two theories on what causes migraines. One is that the blood vessels of the brain either become more narrow (constrict) or become wider (dilate). Constriction of blood vessels can decrease blood flow to parts of the brain. This causes problems with vision or dizziness. Dilated blood vessels press on nearby nerves, causing pain. Another theory is that the rise and fall of chemicals in the brain can cause migraines. One of these chemicals is serotonin. The trigeminal nerve system provides feeling for the face, teeth, mouth, and nasal cavity. The system does not cause migraines but can be part of the reason why you get throbbing pain, especially on one side of the face or behind the eyes.

If you had migraine headaches before becoming pregnant, you may have stronger headaches or you may have fewer of them. Women usually have fewer migraine headaches during pregnancy.

Overuse means that you take over-the-counter or prescription headache medicine in higher doses or more often than recommended. Overuse can cause a "rebound" headache. Rebound means that the medicine gives you relief at first, but that once the medicine is eliminated from your body, your headache returns. This is especially true if the medicine contains caffeine. Even if the medicine doesn't contain caffeine, but you drink coffee, tea, or caffeinated soft drinks, you could be more likely to have a rebound headache.

The eye on the same side as the pain will often tear. That eye and your nose will look red and swollen. Cluster headaches occur in clusters or groups, with one ore more headaches happening a day for up to 12 weeks. A person with a cluster headache often has no warning it is about to occur, and the pain is severe and intense. This type of headache can go away in a half-hour or last for several hours. The cluster of headaches can continue for weeks or months, but can also disappear for months or years. Although some people have clusters more often in the spring or fall, they are not caused by allergies.