Researchers found only two drugs known to help migraine-plagued adults reduced the frequency of kids' headaches better than a placebo. And even in those cases, the effect was small - a difference of less than one headache per month compared to the dummy pills.

"Parents should be aware that our medication choices aren't as good as they should be," said Dr. Jennifer Bickel, a neurologist and headache specialist at Children's Mercy Hospitals and Clinics in Kansas City, Missouri.

Bickel, who wasn't involved in the new research, said no drugs have been rigorously tested and approved for preventing migraines in kids, so doctors have to rely on headache drugs made for adults.

Those medicines, she added, are "not a miracle cure."

For cases when medication may not be enough, Bickel told Reuters Health, parents may want to look into relaxation techniques - such as meditation - for kids with chronic headaches.

According to data from the Cleveland Clinic, about 2 percent of young children and 7 to 10 percent of older kids and teenagers up to age 15 get migraines.

In their review, Dr. Jeffrey Jackson from the Medical College of Wisconsin in Milwaukee and his colleagues looked at 21 trials comparing headache drugs to each other or to placebos. They found only topiramate (marketed as Topamax) and trazodone (Oleptro and Desyrel) significantly reduced the frequency of headaches in kids and teens who got regular migraines.

Other adult headache prevention medicines, including flunarizine, propranolol and valproate, were of no help.

"All the drugs in our analysis have been found effective in adults with migraine headaches, but few were beneficial among children," Jackson's team wrote.

"This suggests there may be something different about pediatric migraines or that the response to treatment differs between children and adults."

Bickel said there is the least research on the one percent of kids who are most severely affected by migraines - those with chronic daily headaches. For those youth, "we don't have any evidence to suggest that the medications are enough," she added.

POWER OF PLACEBO?

In the new analysis, published Monday in JAMA Pediatrics, placebo pills alone led to a drop in kids' headache frequency from between five and six headaches per month to three per month.

That may have to do with the effect of seeing a doctor and being reassured the pain isn't due to anything serious, Bickel said.

According to a report from the U.S. Food and Drug Administration published in the same journal issue, two drugs - almotriptan malate (Axert) and rizatriptan benzoate (Maxalt) - are approved to treat (but not prevent) headaches in kids and teens.

In a review of evidence provided to the FDA, Dr. William Rodriguez and his colleagues also found kids tended to get better after treatment with a placebo more often than adults - possibly related to their headaches lasting less time anyway.