Pyrethrum

What other names is Pyrethrum known by?

Chrysanthème Insecticide, Chrysanthemum cinerariifolium, Dalmation Insect Flowers, Dalmation Pellitory, Pelitre, Piretro, Pyrèthre, Pyrèthre de Dalmatie, Pyrethrum cinerariifolium, Tanacetum cinerariifolium.

What is Pyrethrum?

Pyrethrum is a plant (Chrysanthemum cinerariifolium). Pyrethrum is also the name of the crude extract obtained from flowers of this plant.

Be careful not to confuse pyrethrum with pyrethrin. Pyrethrin refers to a more refined extract of pyrethrum. Pyrethrin is in body lice medicines such as A-200 Pyrinate, Barc, Lice-Enz, Licetrol, Pronto, R and C, RID, Tisit, Tisit Blue, and Triple X.

People apply pyrethrum directly to the skin as an insecticide, particularly for head lice, crab lice and their nits, and mites (scabies).

Effective for...

  • Head lice and crab lice. Applying pyrethrins to the skin in concentrations of 0.17% to 0.33% for 12-24 hours is effective for treating head lice and crab lice. Pyrethrins are usually combined with piperonyl butoxide (2% to 4%) to increase effectiveness.

Ineffective for...

More evidence is needed to rate the effectiveness of pyrethrum for these uses.

Insufficient Evidence to Rate Effectiveness for...

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

Quick GuideLice & Nits: How to Get Rid of Head Lice

Lice & Nits: How to Get Rid of Head Lice

How does Pyrethrum work?

The active chemicals, the pyrethrins, are toxic to insect nervous systems.

Are there safety concerns?

The commercially available combination of pyrethrins (0.17-0.33%) and piperonyl butoxide (2-4%) seems to be safe when applied to the skin in a nonaerosol product.

Pyrethrum is POSSIBLY SAFE when used on the skin in amounts less than 2 grams. While pyrethrum has limited toxicity at low doses, it can cause some side effects such as headache, ringing of the ears, nausea, tingling of fingers and toes, breathing problems, and other nervous system problems.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Not enough is known about the use of pyrethrum during pregnancy and breast-feeding. Stay on the safe side and avoid use.

Children: It's UNSAFE to put pyrethrum on children less than two years old.

Asthma: Exposure to pyrethrin might make asthma worse. Avoid using pyrethrum or pyrethrin products if you have asthma.

Allergy to ragweed and related plants: The pyrethrum flower or pyrethrin extracted from it may cause an allergic reaction in people who are sensitive to the Asteraceae/Compositae family. Members of this family include ragweed, chrysanthemums, marigolds, daisies, and many others. If you have allergies, be sure to check with your healthcare provider before using pyrethrum.

Dosing considerations for Pyrethrum.

The following doses have been studied in scientific research:

APPLIED TO THE SKIN:
  • For treating head lice and crab lice: An over-the-counter (OTC) product that combines pyrethrins (0.17% to 0.33%) and piperonyl butoxide (2% to 4%) is applied to the affected area and allowed to remain for at least 10 minutes. The product is then thoroughly washed off with warm water. Pyrethrins are extracted from pyrethrum, and kill lice by harming their nervous systems.
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Reviewed on 3/29/2011 12:35:40 PM

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