MODEL RELEASED. Feverfew in medicine, conceptual composite image. Feverfew (Tanacetum parthenium, lower right) is a herb that has been used for centuries to reduce fevers and treat headaches and migraines. The digital thermometer at lower left shows 38.47 degrees Celsius, slightly higher than the normal body temperature of around 37 degrees. A high temperature is usually caused by an infection. A stethoscope is also seen (upper right).