CHICAGO -- A new study found that sugar pills worked as well at preventing kids' migraines as two commonly used headache medicines, but had fewer side effects.

The results may lead doctors to rethink how they treat migraines in children and teens.

It's the first rigorous test in kids of two generic drugs that are also used for adults' migraines.

They are the anti-seizure medicine topiramate and the anti-depressant amitriptyline. Both drugs reduce by half the number of days kids had migraines over a month's time. But so did placebo sugar pills.

The study was released online Thursday in the New England Journal of Medicine.