Extract that can be very soothing to skin but also potentially sensitizing if a specific constituent of the feverfew plant known as parthenolide (technically, sesquiterpene lactone) is present. If the parthenolide is removed from feverfew, the ingredient is not a problem for skin and may actually be beneficial because parthenolide-free feverfew has potent skin-soothing properties and can help to diminish redness.
If a skincare product contains feverfew, you must contact the company to confirm that the feverfew in their products is parthenolide-free. Note: All Paula's Choice products that contain feverfew are parthenolide-free.
References for this information:
Journal of Dermatological Sciences, December 2013, pages 304-31
Pharmacognosy Review, January-June 2011, pages 103-110
Archives of Dermatologic Research, February 2008, pages 69-80