September 22, 2023: Why use Emmenagogues?


September 22, 2023

Why use Emmenagogues?

First of all-what is an emmenagogue? Emmenagogues are herbs or plants that are used as supplements to stimulate menstrual flow. The thought is that blood flow is increased to the pelvic area and uterus, which may stimulate menstruation. Efficacy data is lacking for many of these products. Nutraceuticals are also an unregulated industry with no jurisdiction or oversight by the Food and Drug Administration. Some of these products, when taken in excessive dosing, can result in severe systemic toxicity.

Pennyroyal oil: Mentha pulegium is in the mint family and has a fragrance similar to spearmint. Pennyroyal is supposed to enhance the release of the uterine lining. Pennyroyal oil contains pulegone which is a monoterpene and is thought to be the causative agent of toxicity. This is a known hepatotoxin that has a clinical picture, like acetaminophen poisoning. Neurotoxicity, including seizures, has been reported.

Rue: Ruta graveolens comes from a Mediterranean shrub and is typically consumed as a tea. Rue has been associated with multi-organ system failure, particularly liver failure.

Blue Cohosh: Caulophyllum thalictroides has been used as a labor induction agent. The alkaloid that is thought to be the primary agent is n-methylcytisine, which is similar to nicotine. When used in high doses, nicotinic effects may predominate. Given that nicotinic receptors are both on the sympathetic and parasympathetic sides of the autonomic nervous system, the patient may manifest muscarinic signs (“SLUDGE” mnemonic) in addition to sympathomimetic effects such as tachycardia, hypertension, and seizures. Of note, other compounds in the herbal have vasoconstrictive properties, which can also promote hypertension.

Of note, black cohosh is used as a dietary supplement for hot flashes and other menopausal symptoms. Liver injury has been associated with black cohosh, but causation is not definitive.


Bakerink JA, et al. Multiple organ failure after ingestion of pennyroyal oil from herbal tea in two infants. Pediatrics 1996:989:944-47

Feng C, et al. Toxicities of herbal abortifacients. Am J Emerg Med 2023;68:42-46.

Question submitted by Saralyn Williams, MD, Professor of Emergency Medicine, Internal Medicine, and Pediatric.

Comment: Great Question. Pennyroyal oil is an essential oil that is used as an abortifacient. Toxicity can occur with ingestion of more than 10 mls. Use as an abortifacient is certainly one of the herbal practices that you will see in Tennessee. It is a good reminder to always ask about the ingestion of any OTC supplements. ds

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Professor Emeritus
Department of Medicine






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