Only Migrelief contains Puracol™, a whole herb, GMO-free feverfew with all of its therapeutic constituents intact and a high parthenolide content. Puracol™ is the most potent whole leaf feverfew available. Puracol™ contains high levels of parthnolide and assures the presence of all naturally occurring feverfew compounds which extracts may remove. Directions. As a dietary supplement, take one table twice daily or as directed by your healthcare professional. Benefits should be noticed in 4-8 weeks.