Natural D-Hist contains natural and powerful anti-histamine and respiratory/sinus beneficial herbs and nutrients. These include Quercetin, Stinging Nettles Leaf, Bromelain, and N-Acetyl-Cysteine. This product is a great choice for allergy sufferers and it really works! There are NO stimulants in this product. If you suffer from continuous or seasonal allergies you have to give this product a try. Try D-Hist Jr. for the kids! It is a great tasting chewable that the kids love!