http://www.kellymom.com/herbal/ref/herbs_e.html
In normal doses, Echinacea is among the herbs generally recognized as safe for pregnant and lactating mothers. Many people take echinacea, which is reported to boost your immune system (among other things). According to Hale, purified echinacea extract is relatively nontoxic even at high doses. Although no studies have been done on its transfer into human milk or its effect on lactation, no known contraindications to its use during nursing exist other than allergy to the plant family Asteracea (sunflowers).