Yarrow essential oil is a volatile oil including a chemical called proazulenes. The dark blue essential oil, extracted by steam distillation of the flowers, is generally used as an anti-inflammatory or in chest rubs for colds and influenza. Yarrow oil has a sweet, spicy smell and the viscosity is watery. It is a perennial herb that grows up to 1 meter (3 feet) high and has fern-like feathery leaves and bears numerous pink-white, dense flower heads. It is also known as milfoil, referring to its feathery appearance and was used as a charm in Scotland and was credited with having powe...