Pennyroyal
by Ela Heyn
Summer will be soon upon us ... wonderful days on the beach, by the lake, basking in the backyard, kids home from school, and picnics in the woods. Oh, and yes ... fleas and ticks, unfortunately, too.
Around this time of year, a lot of people post to various lists looking for herbs and other solutions to keep pests at bay. One solution that is often suggested is pennyroyal, an herb related to the mint family.
Pennyroyal first became popular in the first century, when the Roman naturalist Pliny noted that skin rubbed with this aromatic herb would repel fleas. Its nickname became "fleabane", and it was found to also repel other insects such as mosquitoes and flies.
Early American colonists introduced the European version of this plant into the United States, but found that the Native Americans were already using a native variety of this plant for insect repellant and other purposes.
There are actually two forms in which one can acquire this herb, and the
distinction is quite important. There is a pennyroyal essential oil, which
is a VERY potent version of the active ingredients in this herb. In an adult
human, as little as 1/2 teaspoon of pennyroyal essential oil can produce
convulsions. The essential oil is also well known as an
abortifacient (substances which induces abortions), and the Journal of the
American Medical Association reports the case of an 18-year-old woman dying
within 2 hours of ingesting 2 tablespoons, despite receiving emergency medical
treatment. The essential oil should be used with extreme caution around
animals, if at all, and pregnant animals should NEVER be exposed to it.
The herb itself, however, is considerably less toxic, and pet beds and pet collars can be stuffed with the dried herb to repel insects safely. University of Illinois pharmacologist Norman Farnsworth, PhD estimates it would take 75 gallons of a tea made with pennyroyal herb to approach a potentially toxic dose of pennyroyal essential oil.
The dried herb can often be bought from online herb vendors. Pet owners interested in growing the herb themselves can contact their local nursery or Richter's to obtain plants.