Rep. Michele Bachmann told a crowd in Aiken, S.C., today that her migraine headaches are under control with medication and would not affect her ability to be president, playing down reports that the ailment has prevented her from doing her job.
Her spokeswoman told ABC News earlier today that the migraines have not interfered with her presidential campaign or her ability to serve as a member of Congress. She denied reports that Bachmann's migraines have "incapacitated" her in the past.
"Twelve percent of Americans suffer from migraines, so if you're saying that Americans who suffer from migraines can't do their jobs, then I think you're going to run into problems," said Alice Stewart, a spokeswoman for the Minnesota congresswoman.
But doctors who specialize in treating migraines say that while they can't speak for Bachmann, 55, many migraine sufferers experience headaches that can be incapacitating.
"The World Health Organization has ranked migraines in its top 20 incapacitating disorders during an attack," said Dr. Jan Brandes, assistant clinical professor in the Department of Neurology at Vanderbilt University in Nashville, Tenn. "They can be as incapacitated as someone who suffers from quadriplegia."
Brandes says about 10 percent of migraine sufferers experience incapacitating headaches, but data from some studies indicate as many as 50 to 80 percent of people with migraines report being severely debilitated.
Dr. Joel Saper, founder and director of the Michigan Headache and Neurological Institute in Ann Arbor, said, "Two to three days of debilitation is not unusual. You have not only the pain but you have nausea, sometimes vomiting, a visual aura and other neurological disturbances as well as a mental fog that can be caused by the pain or the headache itself.
"We grade these things from 1 to 5," Saper said. "If it's a very severe 4 or 5, some people can't get out of bed, they're dizzy or they vomit and they're just in bad shape."
Medications can also affect the ability to function because they often have a sedative effect or cause nausea while making the pain go away.
People experiencing severe migraines might also not be able to think clearly and be unable to move, because any movement at all can exacerbate the pain.
"Many people want to be in a still, dark place with very little sound," Vanderbilt's Brandes said. "People are not really functional during this kind of attack."
ABC News' Brian Ross, Matthew Jaffe and Z. Byron Wolf contributed reporting.