Feverfew dangers?

Botanical name: 

Newsgroups: alt.folklore.herbs
Subject: feverfew: effective but possibly dangerous
Date: 15 Jun 1995 17:52:31 GMT

I looked up feverfew in Medline and would like to report what I found there. If you aren't interested in medical experimentation as it applies to herbs, you will probably not be interested in what follows.

The good news (for migraine sufferers): I found two double blind experiments looking at the effectiveness of feverfew on migraines: The first one used 72 migraine sufferers. Half got a capsule per day of feverfew, the other half got a placebo. There was a significant reduction in the mean number and severity of migraine attacks.
The other experiment looked at 17 migraine sufferers who normally ate feverfew to control headaches. They gave placebos to some and continued the feverfew with others. The placebos increased frequency and severity of migraines.

The bad news: Feverfew affects the smooth muscles of the body. These are muscles that control much of your involuntary muscular processes, such as the vascular system (blood vessels), digestive system, internal organs, aorta, etc. From what I can gather from some of the abstracts in Medline, feverfew PERMANENTLY affects the ability of these smooth muscles to contract and relax. Here are some snippets from the abstracts which looked at this:

"(Feverfew)...inhibits smooth muscle contractibility in a time-dependent, non-specific, and irreversable manner."

"(Feverfew)...affects smooth muscles...may represent a toxic modification of post-receptor contractile function in the smooth muscle...effects are potentially toxic"

"...inhibition of eicosanoid generation is irreversable"

"...irreversable loss of tone of precontracted aortic rings...inhibited ability of acetylcholine to enduce endothelium dependent relaxation of tissue."

What does this all mean for the long term health of those who take feverfew? That does not seem to have been looked at yet; these articles were very recent. However, I think that people who take feverfew should know that they may be permanently affecting the smooth muscles in their bodies and may want to take this into account when deciding whether or not to continue taking it.

From: Gregg Pond <gpond.integ.micrognosis.com>

> I have been taking feverfew for migraines and it seems to end my migraines in a relatively short period of time. Has anyone else used feverfew for migraines? Have you had any side effects?

I also have been taking feverfew for the migraines. The only side effect I have seen is they are far less frequent than when I started taking the feverfew. This makes me believe that the warnings being posted about the soft tissue effect on this news group, is a lasting effect that my system needs. I used the feverfew originally for a 3 month period, then stopped taking it. I went from 3 migraines a week to maybe 1 every couple of months. If I suddenly start getting them frequently again, I take the feverfew for a week and it corrects the problem.
I take it in an extract form, 15 drops twice a day.


References about feverfew and its possible detrimental effects on smooth muscles

  • Barsby, R.W. et. al. Feverfew extracts and parthenolide irreversibly inhibit vascular responses of rabbit aorta J Pharm Pharmacol, 1992 Sep;44(9); 737-40.
  • Hay, AJ et. al. Toxic inhibition of smooth muscle contractility... Br J
    Pharmacol, 1994 May; 112 (1); 9-10
  • Barsby. RW et. al. A chloroform extract of the herb feverfew blocks... J Pharm Pharmacol, 1993 jul; 45(7):641-5
  • Barsby, RW et. al. Feverfew and vascular smooth muscle... Planta Med , 1993 Feb; 59(1)
  • Sumner, H. et. al. Inhibition of 5-lipoxygenase and cyclo-oxygenase in leukocytes by feverfew Biochem Pharmacol, 1992 Jun 9; 43(11): 2313-20.
  • Barsby et. al. Irreversible inhibition of vascular reactivity by feverfew (Letter) Lancet, 1991 Oct 19; 338 (8773); 1015

And, studies that showed that feverfew is effective in migraines...

  • Murphy, et. al. Randomised double-blind, placebo controlled trial of feverfew in migraine prevention Lancet, 1988 Jul 23;2 (8604);189-92.
  • Johnson ES et. al. Efficacy of feverfew as prophylactic treatment of migraine Br Med J (Clin Res Ed) 1985 Aug 31; 291 (6495); 569-73.

I didn't show the entire title of some of them because they were too long. (I had to copy it down from Medline by hand.)

From: hd987.cleveland.Freenet.Edu (Eugenia Provence)

I got into Medline myself after reading the post "Feverfew References".

There can't be enough said to emphasize the difference in studies of isolated plant components, like feverfew's parthenolide, and in studies of the effect of whole plant extracts.

The isolated sesquiterpine parthenolide is toxic to just about anything. The parthenolide studies were done in vitro, using excised muscle tissue from rats or bunnies.

None of the whole-plant studies on humans found *any* toxicity.

The *only* precautions in taking feverfew for migraines are (1) not to take in pregnancy, because of the stimulant action on uterine smooth muscle tissue, (2) some people may get mouth ulcers from using the fresh leaves.

Additional benefits from whole-plant use in humans included relief from depression and arthritic pain due to inflammation.

In one of David Hoffmann's lectures at California School of Herbal Studies, he said that Feverfew is an excellent example of the synergistic actiony of plants. The isolated parthenolides don't work on migraines, nor does the whole plant with the parthenolides removed. The parthenolide is bioavailable only in the whole plant.

Fresh or freeze dried preparations are best, and this is one of the few instances where he recommended standardized extracts.

Steven Foster has a very good monograph on Feverfew: Botanical Series No. 310, $1.00, available from the American Botanical Council, P.O. Box 201660, Austin, TX 78720 or (800)373-7105.

If you're taking feverfew for migraine prevention, for heaven's sake, just ignore all the smooth muscle stuff. You're not a piece of muscle tissue in a test tube.

I'll send the Medline cites and a couple of abstracts to anyone who is interested.

Medicinal herb FAQ: http://www.henriettes-herb.com/faqs/medi-2-9-feverfew.html


(he sent me this in April ... and I only got around to it today. Sorry about that.)

Hello, I'm the 'AJ Hay' chap that carried out the experiments on feverfew in the early 90s. I took forward the research that 'Barsby' had performed in the lab the years prior to me. If you'd like more info about feverfew from me directly please feel free to ask. As you can see [...], I went on to study and become a homoeopath. I no longer work in the pharmacology research field but still find it fascinating.

What I will say about the findings of the research is that it is impossible to say from the results whether the effects that we saw were due to the toxic or therapeutic effects of feverfew or indeed a mish-mash of both.

We were using an extract and not 'pure' feverfew. Extracts have had constituents removed that are deemed inactive. The removed constituents may, in fact, act as balancers or buffers in the feverfew plant, making it much less 'toxic' when taken as a whole.

We were using an experimental model outside the living organism and not directly on humans. Unpublished data using the same extracts also showed interesting effects on the aggregation of human platelets in a manner vaguely similar to aspirin, in that it also seemed to inhibit one of the prostaglandin pathways.

These factors must be considered before denouncing feverfew as dangerous.

The most 'active' feverfew is fresh, but when chewed has the potential to cause blistering in the mouth of susceptible individuals. When taken fresh it is advised to eat with bread to buffer the impact on the mouth and palate.

In previous research carried out by Barsby it was apparent that tablets containing dried feverfew had much less 'active ingredients' tinctures made from fresh herb were second to fresh leaf.

Kind regards,

Alastair Hay - www.homeopathical.com

Thanks for that!