What do Julius Caesar, Thomas Jefferson, Elizabeth Taylor and Elvis Presley all have in common? Unfortunately, all have suffered from migraine headaches, those severe, debilitating headaches that typically appear as throbbing aches near the side of the forehead.

Have you had them? Are they frequent? You aren't alone. Nearly 30 million Americans suffer from migraine headaches.

At times, migraine headaches can be unbearable. They can interfere with your emotional life, work, school and family routines. These interruptions can last beyond the time of the headache itself. Some migraine headaches can be so profound they cause you to seek bed rest for relief.

How do you know if you have migraine headaches? Migraines generally occur at a minimum of once a month. The pain is accompanied by throbbing on one side of your head that is triggered and becomes worse with movement. You may also experience nausea or vomiting as well as light and sound sensitivity.

Some people who experience migraines describe visual symptoms such as seeing shapes or colors about half an hour before their headaches begin. Vaguer symptoms can occur a day or two before an attack, such as mood changes, food cravings, abdominal cramps, diarrhea or constipation. When your migraine attack is over, you may feel irritable and tired.

What causes a migraine?

Researchers are still studying migraines and what causes them. Experts say possible causes or triggers include physical or emotional stress, sleep pattern changes, alcohol or caffeine consumption, and noise, light or certain odors. Some say it may be linked to hormones in women who experience a drop in estrogen just before menstruation. This type of migraine has a tendency to last longer.