Your head is throbbing, your stomach is queasy and bright lights or loud noises make you feel even worse. If you're one of the estimated 30 million Americans who get migraine headaches, you know these classic symptoms of a migraine attack. Learn possible causes, treatments and how to get help...

Although "migraine" is often used to describe any splitting headache, a true migraine headache has distinctive characteristics. For one thing, the pain is typically moderate to severe, with a throbbing or pulsating feeling. A migraine attack generally lasts between four and 72 hours, but, in some cases, it can linger an entire week.

Other symptoms of migraine headaches include nausea or vomiting, or sensitivity to light, sound or odor. In about 60% of cases, the pain centers on one side of the head and face.

An aura, an uncommon reversible neurological symptom, may also occur shortly before or at the onset of pain and last five to 60 minutes. The most common type of aura involves visual changes: You may see spots, specks or wavy or shimmering lines, usually in just one side of your visual field.

Less common are sensory auras, which involve numbness or tingling in the hands or face, or language auras, in which people have trouble speaking.

"Only about 20% of migraine patients will experience [an aura]," says neurologist Brian M. Grosberg, M.D., director of the Montefiore Headache Center in New York City.

When headache pain is accompanied by speech difficulties, it's important to rule out other serious conditions such as stroke and seizures, which can cause similar speech and language problems, he says.

Migraines occur most often in adults between 20 and 50 years old. They're three times more common in women than men, although doctors don't understand why. Experts say hormones play a role.