Rarely though, Yarrow flowers are known to cause skin rashes. They sensitize the skin to sunlight and exposure to sunlight soon after handling yarrow plants, may cause sunburns. Do not use in pregnancy. Yarrow causes headache and dizziness in large doses.
Do not take zinc supplements in quantities more than 25mg in a day unless prescribed by a doctor. Zinc supplements may impair immunity if taken in excess. Zinc supplements must always include copper for best results.