Frankly, the causes of migraine headache are poorly understood. There is probably a genetic component as your chances of getting these headaches increases with having family members with the same problem. Migraines are definitely multifactorial, so if we can take away some of the factors, we can prevent the migraine. We will focus on the environmental factors, since this is something you can change.
There are four parts to a migraine, though you won't necessarily have all these parts.
Prodrome — Happens 1-2 days before the migraine and can include constipation, diarrhea, depression, food cravings, hyperactivity or irritability, or neck stiffness.
Aura — Happens in the hour or so directly before the headache, lasts 10-30 minutes and is experienced by the minority of migraine sufferers. Usually visual: seeing shapes, bright spot, flashes or vision loss. Can also be sensory (like pins and needles in arms or legs), motor or verbal disturbances.
Attack — Lasts 4-72 hours, throbbing pain on one side of head; light, sound, smell sensitivities; nausea and vomiting; blurred vision and light headedness. Click here to compare tension and migraine headaches.
Postdrome — After the migraine, may feel drained and washed out.
Dehydration — Not drinking enough water, drinking too much caffeine or alcohol, or over exertion/over heating can create cellular dehydration, increase blood flow to the brain, and precipitate a headache. I deal with this more thoroughly in the Dehydration Headache page.
Trigger points — The best way to find out which muscles might be effected, is to choose your pain pattern from the What Causes Headache page and work through them systematically. Use the various methods outlined on the Trigger Point Treatment page to eliminate them.
Stress — Stress effects our bodies in so many ways and can be one of the main causes of migraine headache in some people. This is partly because it tends to make us tense our muscles. It also changes our biochemistry and puts us in a state of "fight or flight" which creates many problems (including headaches) when we stay that way for extended periods of time. Learn more about healthy ways to deal with your stress.
Foods — Certain foods can trigger migraines in some people. These include alcohol, but especially the sulfates added to preserve the wine, beer, and dried fruit; aged cheese, chocolate, aspartame, and MSG. The blood sugar dip caused by skipping a meal can be one of the causes of migraine headache.
Hormonal changes in women — Fluctuations in estrogen seem to trigger migraines in susceptible women, creating migraines immediately before or during periods. Can be worsened by hormonal medications.
Sensory stimuli — Visual: Bright lights, sun glare, flashing lights. Sounds: loud or repetitive sounds. Smells: perfume, paint thinner, smoke.
Changes in wake-sleep pattern — Missing sleep or getting too much sleep, jet lag.
Changes in the environment — Change of weather or barometric pressure.
Medications — Certain medications can aggravate migraines, especially oral contraceptives and vasodilators, such as nitroglycerin.
With so many causes, how do you figure out what is causing the headaches for you? I recommend making sure you are hydrated and that you don't have any obvious trigger points creating the pain first. If that is not enough, then try keeping a headache diary. Here is a link to information from the National Headache foundation:
If that is not enough, then try keeping a headache diary. Here is a link to a website called MigraineSavvy written by a migraine sufferer with much more information. In this section, she explains how and why to keep a headache diary as well as other tracking tools, and links to much more information.
Don't get discouraged. Migraines are very hard to beat on your own. Start with the information here and you should make some progress. Then seek help from a professional. I recommend finding a chiropractor with experience treating migraines first. Then try an experienced acupuncturist. If you still don't find relief, you may need medication as well.
Hope this helps!