While there are few drawbacks to aromatherapy, there are some that could be very dangerous. In some aromatherapy cases, oils are used and rubbed onto the skin. These oils have chemical properties that can enter the bloodstream, and for some patients they may be very dangerous when used with certain cancer therapies such as chemotherapy or radiation. Also, people with high blood pressure or diabetes or who are pregnant should avoid certain oils. You should consult with your doctor if you have any serious medical conditions before starting any type of aromatherapy.