Feverfew is a traditional well-known and much loved herb used extensively in Chinese medicine, but the essential oil is little used presumably because of the very high (48%) camphor content.
As its name implies, in folk medicine the dried leaves and flowers are used for immune support, and as a general tonic. It also has a reputation as being helpful for the musculoskeletal and digestive systems, but is contra-indicated for pregnant women, as would be the essential oil.
Of course it is unwise to project these characteristics definitively to the essential oil, about which little has been written, but it may give us some clues.
The plant, an obvious asteraceae, spreads rapidly and can be found improbably but persistently growing in the cracks between paving stones in traditional gardens. It is related to the Tansy which hugs the hillsides in Morocco, the oil of which is also ketonic.
This is a pure therapeutic-quality wild-crafted aromatherapy essential oil from Bulgaria, and is obtained from the whole plant.