WASHINGTON — Western medicine doesn't have the market cornered on making children feel better: Some products from health food stores work like a charm with sick children, an expert on "alternative" remedies told fellow pediatricians recently.

But other widely available supplements can sicken or kill kids, Cora Collette Breuner said at the American Academy of Pediatrics meeting in Seattle this month.

Unfortunately, pediatricians can't warn most families of dangers, she says; surveys show only about one-third of parents tell doctors about these alternative medicine purchases.

"Pediatricians should ask and parents should be open about what they're giving kids," says Breuner, a pediatrics professor at University of Washington Medical School in Seattle. "We docs tend to downgrade the entire field of herbal and health food products because some of it is contaminated, and that's not fair."

Studies suggest 11 percent to 15 percent of parents use some form of complementary medicine with their children, she says. Herbal supplements commonly are used, and some work.

Herbs such as peppermint and chamomile can soothe children's upset stomachs, she says. Ginger capsules or tea made from fresh ginger also help, says Wake Forest University pediatrician Kathi Kemper, author of "The Holistic Pediatrician."

And probiotics in capsule or powdered form can ease children's diarrhea, Kemper says.

On the other hand, there's no evidence that the wildly popular herb echinacea prevents or shortens children's colds, Breuner says.

Some seemingly harmless natural products may hurt children and teenagers. Garlic, for example, lowers cholesterol up to 10 percent, but it also thins blood, Breuner says. That can increase bleeding in young athletes, she says. Saint John's wort interacts with many medicines, for example, lowering the potency of birth control pills, she adds.

Some so-called natural weight loss products favored by girls might upset their balance of electrolytes, predisposing them to heart arrhythmias, Kemper cautions. Also, certain diet supplements have dangerous stimulants such as ephedra, she says.

Teenage boys who want to "bulk up" might convince their parents it's OK to try innocent-sounding products such as protein powders that turn out to be laced with steroid hormones, according to Kemper.

Sometimes these products are harmless, but contaminated supplements can cause kids to stop growing and even be toxic to the liver, she warns.

Parents should avoid herbal products from developing countries, "particularly China, India and Mexico," Kemper advises, as many contain lead or other dangerous heavy metals.

"If parents can't read the label, they probably shouldn't give it to their child," she says. "We've even seen these 'teething tablets' that look so innocuous, and they end up containing lead."