Studies on chemicals found in essential oils support the pharmacological action of these materials. Modern perfumery usually contains synthesized versions of the chemicals found in nature. While the source of the material may be different, the pharmacological action remains. Materials can effect the brain and nervous system via olfactory pathways, trigeminal stimulation, or absorption into the blood stream via the lungs. Changes in cerebral blood flow are thought to be involved in the triggering of migraines.
Some materials used in fragrances have the ability to alter blood flow in the brain.
1,8-cineol, a common chemical in fragranced products, was shown to increase cerebral blood flow. It was readily absorbed from the air with changes in blood flow resulting after 20 minutes of exposure. Initially there was slight vascular dilatation and then a short period of constriction. The third phase was vascular dilatation that persisted for 24 hours. Another study indicates there are EEG changes in response to low level exposures to fragrances to alter neurophysiology.