Allow me to clear this up. The reason it was on the list is because some people can have a reaction to the plant. It produces mild to moderate stomach upset or dermatitis. The juice, sap, or thorns may cause a skin rash or irritation.
Traditionally and medicinally used in China for tea only the yellow or white flowers are boiled down to make this sweet drink. The tea is prescribed in Chinese medicine for influenza, and it has a cooling effect on the body, so it is used for treating heatstroke.
Chrysanthemum tea also detoxifies the blood; helps with sinus congestion, high blood pressure, and can also calm the nerves. Chrysanthemum Tea can also be used to sharpen vision and hearing, and clear the brain.
So while touching the actual plant's juices may give you a rash, sipping hot tea made from Chrysanthemum flowers has many health benefits.