Herbal Supplement Standardized Extract 0.5%-0.7% Parthenolide A Dietary Supplement Vegetarian/Vegan Botanicals/Herbs Family Owned Since 1968 GMP Quality AssuredFeverfew is an herb that has been traditionally used by European herbalists for centuries. More modern research indicates that its main bioactive compound is parthenolide. Now Feverfew is standardized to 0.5%-0.7% Parthenolide per capsule.