Carcinogenic oils: Calamus (European and Asian) and Sassafras Also ABSOLUTES are extracted with a solvent, usually alcohol or other hydrocarbons (ie:hexane). Because of the volatile nature of them, they're not suitable for aromatherapy

There are some that need to be used with great caution, or that you shouldn't use on some people. There are people that area allergic to some oils or sensitive to smells and they may get an instant headache, nerve problems or congestion with some oils. Some oils are not safe for children. Many people don't realize that oils need to be diluted usually for use. Things to take into consideration are dosage, purity, application, and interactions with other oils or drugs. If someone is pregnant, there are some oils they need to stay away from. If they suffer from a seizure disorder it's best to avoid Basil, Fennel, Hyssop, Rosemary and Sage. And some people suffer from phototoxicity with the application of some oils and sunlight. Some oils should not be used by people who are not trained clinicians like Birch, Sage, Thuja, and Wintergreen. Calamus (European and Asian), Sassafras are carcinogenic. Some that are considered too hazardous to use are: to be avoided at all costs' list are: Bitter Almond, Calamus, Yellow Camphor, Horseradish, Mugwort, Mustard, Rue, Sassafras, Southernwood, Tansy (other than Annual Tansy), and Wormwood.