Pennyroyal

PENNYROYAL | POLEO

Pennyroyal is a plant with a scent like mint, a history that spans continents, and a reputation that swings between healing and hazardous. Known botanically as Mentha pulegium (European pennyroyal) and Hedeoma pulegioides(American pennyroyal), this little herb has packed a punch in traditional medicine for centuries- and not always without controversy.

Pennyroyal is part of the mint family (Lamiaceae), and its intense, almost spicy aroma comes from a compound called pulegone. It’s native to Europe, North Africa, and parts of the Middle East, but quickly made its way into North America, where Indigenous peoples and settlers alike found it useful - sometimes essential - in daily health routines.

In ancient Greece and Rome, pennyroyal was a multipurpose herb. It was used to ease digestive problems, relieve menstrual cramps, and ward off insects- particularly fleas. The name pulegium actually comes from pulex, the Latin word for flea. That’s how common its use was as a natural insect repellent.

But pennyroyal’s most talked-about historical use was as an emmenagogue- a plant used to stimulate menstruation. Across cultures, it was used by women to regulate cycles, ease painful periods, and in some cases, to terminate pregnancies. In medieval Europe and early American folk medicine, this use was widespread and, in many communities, kept quietly alive through oral traditions. It was powerful. And that power came with risk.

As European settlers arrived in North America, they brought Mentha pulegium, but Indigenous peoples were already using the native variety, Hedeoma pulegioides, for similar purposes. Native communities used pennyroyal for head colds, fever, indigestion, and sometimes as a poultice for wounds. It became part of the colonial herbal toolkit- readily planted, widely shared, and deeply respected.

By the 19th and early 20th centuries, pennyroyal showed up in materia medica texts and early pharmacopoeias. It was often included in tinctures and tonics labeled for “female complaints,” a euphemism for everything from painful periods to missed ones. Pennyroyal oil was even sold in pharmacies- though even then, it was understood that the essential oil was highly toxic and should never be ingested in pure form.

Today, we know that pulegone, the main compound in pennyroyal, can cause serious liver and kidney damage, and in concentrated forms, can be fatal. Modern herbalists still use the dried herb with caution in external applications, or in extremely diluted infusions, but it’s not a casual cup of tea. Its historical role as a powerful herbal ally - especially in women’s reproductive health - remains, but it comes with a heavy disclaimer.

Pennyroyal is a perfect example of a plant that demands deep respect, informed use, and cultural memory. It reminds us that “natural” doesn’t always mean “safe,” but it also shows us how people throughout history relied on the Earth for care, control, and autonomy.

Medicinal Uses of Pennyroyal

• Stimulates Menstruation (Emmenagogue)
  Historically used to bring on delayed periods, ease menstrual cramps, and regulate the menstrual cycle. This was one of pennyroyal’s most common uses across cultures in both Europe and North America.

• Digestive Aid
  Pennyroyal tea was traditionally used to soothe indigestion, gas, and bloating, especially when tied to nervous tension or cold, sluggish digestion.

• Relieves Head Colds and Congestion
  The herb was used in steam inhalations and teas to help relieve mild fevers, sinus congestion, and coughsassociated with colds and respiratory infections.

• Insect Repellent
  The intense aroma of pennyroyal made it a natural choice for repelling fleas, mosquitoes, and other insects. It was often placed in sachets, rubbed on the skin (diluted), or added to floor washes.

• Mild Sedative and Calmer of Nervous Tension
  In folk medicine, pennyroyal tea was sometimes taken in small amounts to ease anxiety, calm restlessness, and reduce stress-related digestive issues.

• External Use for Headaches and Joint Pain
  Compresses or poultices soaked in pennyroyal tea were applied to the forehead, temples, or aching joints to reduce pain and inflammation.

• Fever Support and Sweating
  Pennyroyal was also used as a diaphoretic—to induce sweating during fever, helping the body cool down naturally.

• Wound Cleansing and Skin Irritation
  Mild pennyroyal infusions were occasionally applied externally to clean minor wounds or soothe itchy skin and insect bites.