Can you give a child under 5 years echinacea?

Echinacea: Probably, but there is no published reputable dosage published for children that would meet fda standards. The nih published a controlled, double-blind study a few yrs ago (nejm) that showed that echinacea was no better than placebo for bolstering immune function or treating viral upper respiratory infections. That said, placebo is pretty good for most folks!