Herbs & Supplements

Should I take it?

Pennyroyal plants are believed to be native to both North America and Europe. Several species of pennyroyal are now found in most mild climate areas of the world. Generally, these members of the mint family of plants are smaller than other species of mint and they tend to lie along the ground rather than send their short stems upright like most other mints. Perennials, they spread very easily, with new roots forming at the points where leaf-nodes on the stems touch the ground. The leaves of pennyroyal are light or grayish green in color and the flowers, which bloom in mid-summer, are blue or purple. Pennyroyal has a very strong minty smell and a minty-acidic taste that make it popular in Europe for flavoring foods. It is used to make tea and fresh pennyroyal leaves may be added to salads or cooked dishes. For use as a dried herb in medicine or cooking, the stems--including the leaves--are collected before the flowers appear.

Depending on the species, up to about 2% of the "aerial parts" (flowers, leaves, and stems) of the pennyroyal plant consist of volatile oils, primarily pulegone. Volatile oils are also called essential oils. They possess the characteristic smell and taste of the plant and they usually evaporate quickly at room temperature. In most cases, European pennyroyal contains up to three times as much pulegone as American pennyroyal. Oil distilled from pennyroyal may be used topically as a skin antiseptic or as an insect repellant. In fact, some of its common names (mosquito plant, tick weed) suggest that it has good ability to repel insects and other pests. Some commercially available flea-repelling products for pets contain small amounts of pennyroyal oil, but the death of at least one dog has been documented after pure pennyroyal oil was applied extensively to control fleas. Pennyroyal oil may be included in cosmetics, perfumes, and soaps as a fragrance. It is approved in some countries as a food flavoring, but usually only after the pulegone has been removed.

Dosage and Administration

Pennyroyal oil should not be taken orally.

No dosage recommendations for either oral dried pennyroyal leaves or topical pennyroyal oil have been found in the clinical literature. Because pennyroyal tea and other oral forms of pennyroyal contain very little pulegone, they may be safe to take in small amounts. Pennyroyal oil should be used only topically and only very cautiously because it may be absorbed through the skin.

Summary

Pennyroyal leaves and stems may be dried and used to treat mild stomach complaints such as indigestion. Oil of pennyroyal has been used topically to disinfect skin wounds and to repel insects. Since using either form presents the possibility of severe side effects; however, neither can be recommended for use.

Risks

Pennyroyal should not be taken or applied by pregnant women because it is known to have caused miscarriages. Swallowing it has resulted in death or liver damage in small children. Therefore young children and breast-feeding women should also avoid using pennyroyal. It should also be avoided by individuals with kidney, liver, or lung conditions.

Side Effects

The pulegone in pennyroyal has been known to cause:

• Kidney damage
• Liver damage
• Lung damage
• Nerve damage
• Shock
• Death

Pennyroyal can also cause central nervous system effects such as confusion or gastrointestinal effects such as nausea and vomiting.

Interactions

Although no interactions have been identified between pennyroyal and drugs, herbals, or foods; interactions may exist.

Last Revised April 15, 2008