Pyrethrins - Fact Sheet

Pyrethrin - Natural insect control for your home, garden and pets

Natural pyrethrum from ChrysantehemumsPyrethrin is a natural insecticide, derived from the crude extract of the Chrysanthemum flower (Pyrethrum). It has been used to control pests for over a century and is generally considered quite safe. There are two types of Pyrethrins found in these flowers - appropriately called Pyrethrin I and Pyrethrin II - they are usually combined in pest control formulas.

Pyrethrin should not be confused with pyrethroids (such as Permethrin) which are synthetic insecticides. The natural and artificlal substances, though similar, have different properties and important differences in their level of safety, especially around pets.

Pyrethrins are considered one of the insecticides least toxic to mammals. They are biodegradable and break down in the environment with exposure to light.

How to Use

Pyrethrin products are available in powders and sprays. They are also found in bug bombs and foggers and head lice treatments. You can use a duster or fogger to distribute the powdered products. Dusters are effective at getting pyrethrin powder into cracks and crevices around your house - a must if you are trying to get rid of bedbugs!

As with any insecticide, always use as directed and pay special attention to precautions and instructions shown on the product label.


Pyrethrin is an insecticide which works by having a neurotoxic effect on insects. There is evidence that it also has some insect repellent properties. It is often combined with other substances, such as piperonyl butoxide (a synthetic sassafras oil) which makes the insects more susceptible to the Pyrethrin, or Diatomaceous Earth (silicon dioxide) a safe, mechanical insecticide which works by drying out the insects' outer skeletons (exoskeletons).

Insecticides such as Diatect® use a combination of all 3 ingredients. These insecticides typically have an EPA classifaction of "least toxic", meaning they have low or no acute or chronic toxicity to humans, affect only a limited number of species and can be applied in a way that limits or prevents exposure to any organisms except the pests they are meant to control.

Pyrethrin is effective against many insects, including fleas, ticks, ants, roaches, bedbugs, silverfish, lice, mites and mosquitos.

Pyrethrins and Pets

Pyrethrin is the active ingredient in many commercial flea and tick products, particularly powders and sprays. Unlike Permethrin, Pyrethrin flea and tick control products can be used on cats.

Although Pyrethrin is a "natural" product, there can be toxicity issues if it is ingested, or overused - follow your vet's instructions and precautions on the label and use with care! Signs of pyrethrin toxicosis include trembling, vomiting, drooling and sometimes seizures. If you note any of these symptoms after using a Pyrethrin product on your pets, promptly consult your veterinarian.

Pyrethrin is toxic to fish and should NOT be used around fish or fish ponds.

Additional health precautions

Pyrethrin/Pyrethrum can aggravate asthma in susceptible individuals.

Pyrethrum and Pyrethrum can cause an allergic reaction in people who allergic to ragweed and related plants, including daisies, marigolds and chrysanthemums. If you have any of these allergies, talk to your health provider before using Pyrethrin or Pyrethrum products.


Pyrethrin is a naturally-derived pest control substance with a high safety rating which is effective against many types of insects . Use may be contra-indicated for individuals with certain health issues. As with any product, carefully read and follow the label precautions and instructions for use.

Pyrethrin Products