Feverfew (Tanacetum parthenium)

Feverfew was commonly used by the early Europeans and Greeks to treat fevers, headaches, arthritis, menstrual problems, and other generalised aches and pains. Today, the plant is most commonly used to reduce the frequency and severity of migraines - several placebo-controlled human trials have confirmed feverfew’s effectiveness in this area. The active ingredient in feverfew is a compound called parthenolide, which belongs to a group of compounds known as sesquiterpene lactones. Parthenolide prevents the excessive clumping of platelets in addition to inhibiting the release of certain chemicals, including serotonin and some inflammatory mediators. Feverfew’s anti-migraine action was originally attributed to its parthenolide content, however this has been a subject of recent debate.

Research carried out by Mazor et al in 2000 suggests that sesquiterpene lactones inhibit the expression of the immunoreactive molecule Interleukin (IL) 8, a discovery that could account for feverfew’s anti-inflammatory actions. One study also found that low concentrations of parthenolide were able to inhibit growth of tumor lines in vitro.

Feverfew is sold dried and in capsules, concentrated drops, tinctures and extracts. The newest products are standardized for 0.1 to 0.2% of the chemical parthenolide, , however standardized leaf extracts may contain as much as 0.7%. An average daily dose is 125mg of feverfew (standardized for 0.2% parthenolide) or 250mcg parthenolide. A number of studies done in the last 10 years indicate that several commercial feverfew products contained none of the active compound parthenolide (in addition, parthenolide levels of the dried herb were found to fall during storage). These studies emphasize the importance of using high-quality standardized extracts of this herb in order to obtain proper dosage and reliable effects.

MAXIMUM SAFE LEVEL: Not established

Few side effects have been associated with feverfew products, although eating the fresh leaves can cause swelling of the lips and tongue and mouth ulcers. A withdrawal syndrome called "post-feverfew syndrome" has been described, with symptoms including: nervousness, tension headaches, joint stiffness, and tiredness. People who are allergic to other plants in the daisy family, such as chamomile or ragweed should not take feverfew. The herb is not recommended during pregnancy or lactation and should not be used by children under the age  of two. It has also been reported that the drug may interact with anti-coagulant medicines.