Answer
Its traditional registration is based on longstanding use rather than demonstrated clinical effectiveness.
Sources for this answer
- Care Feverfew Migraine Relief Tablets / MigraEeze Feverfew Tablets — Current selected SmPCemc · Summary of Product Characteristics
- NHS Specialist Pharmacy ServiceNHS Specialist Pharmacy Service · NHS medicine guidance
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.