Studies have found that chamomile is a mild sedative that seems to be safe for children of all ages. (It may trigger an allergic reaction, however, especially if a child is sensitive to ragweed.)
Bottom line: If not allergic to ragweed or other similar plants, drink up.
Herbs for Kids: What's Safe, What's Not
Echinacea. This herb flies off the shelves on the premise that it boosts the immune system and helps fend off colds. Scientific studies, however, have found conflicting results. Kemper reports that taking echinacea can cause dermatitis, but, like chamomile, it seems to be generally safe for children who aren't allergic to it
Herbs for Kids: What's Safe, What's Not