Pennyroyal Tea (Poleo Menta): Uses and Safety Risks

Pennyroyal tea is made from Mentha pulegium (poleo menta), a mint that many people in Spain drink after meals to help digestion. No clinical studies show it works. It contains pulegone, which can harm the liver. Pennyroyal oil can kill, and pennyroyal must never be taken in pregnancy or given to babies. This guide is by Dr. Pedro Yelamo Vera, a GP licensed in Spain (Colegiado No. 484814280).

What is pennyroyal?

It is a herb in the mint family that grows in damp places in Europe and North Africa. In Spain it is sold as tea bags, on its own or mixed with camomile, in supermarkets, health shops and bars. It is called poleo menta or poleo. Despite the name, it is not peppermint.

What is pennyroyal tea good for?

People drink it for heavy meals, wind, colic and colds. These are folk uses. No trials show it works better than any other hot drink. There is also no proof that it helps weight loss or "detox".

Why can pennyroyal be dangerous?

Pennyroyal contains pulegone. The liver turns it into menthofuran and other substances that use up the liver's defences and can kill its cells. The European Medicines Agency (EMA) says pulegone intake should be kept as low as possible. It has set limits for herbal products that contain it.

The risk depends a lot on the form:

• Pennyroyal oil: very strong and very toxic. A tablespoon can cause fainting, fits, coma, liver and kidney failure, and death. It must never be taken by mouth.
• Pennyroyal tea: has much less pulegone. An occasional cup in a healthy adult is usually thought to be low risk, but it is not harmless. Poisoning has been reported, above all in babies.

Can I drink pennyroyal tea when pregnant?

No. Pennyroyal was used for centuries to bring on periods and cause abortion. The amounts that do this are toxic. Young women have died of liver failure. Do not take pennyroyal, as tea or oil, if you are pregnant or trying for a baby. If you have an unwanted pregnancy, see a doctor: there are safe, legal options.

Can babies and children have pennyroyal?

No. There are reports of babies given mint tea with pulegone who had liver failure, fits and died. Do not give pennyroyal tea to babies or young children, for colic or for colds. For baby colic, ask your child's doctor.

Who should not drink pennyroyal tea?

• Women who are pregnant or trying for a baby.
• Women who are breastfeeding.
• Babies and young children.
• People with liver or kidney disease.
• People with epilepsy.
• Heavy drinkers, or people who often take medicines that load the liver, such as high doses of paracetamol: ask first.

It is also best not to drink it every day for a long time. This guide does not give amounts. If you drink it, keep it occasional, use shop-bought tea bags, and never use the oil.

Is pennyroyal good for heartburn?

There is no proof that it helps. Mints can relax the valve between the food pipe and the stomach. In some people they make heartburn and reflux worse. If you get heartburn often, read about heartburn treatment.

Is it the same as peppermint or spearmint?

No. Peppermint (menta piperita) and spearmint (hierbabuena) are other plants with far less pulegone. Their oils still need care and are not for young children.

In English: what is the equivalent?

In the UK and the US the plant is called pennyroyal. Pennyroyal tea is rarely sold there. Pennyroyal oil is sold for aromatherapy and as an insect repellent, and it is not for eating. In a Spanish bar or shop, poleo menta is pennyroyal, menta or menta piperita is peppermint, and manzanilla is camomile.

What are the signs of pennyroyal poisoning?

• Feeling or being sick, and tummy pain.
• Dizziness, sweating, drowsiness or agitation.
• Fits.
• Over the next hours or days: yellow skin or eyes, bleeding and confusion.

When to see a doctor

• You drank pennyroyal while pregnant.
• You notice yellow skin or eyes, dark urine or deep tiredness.
• You have stomach problems that keep coming back. They need a check, not just herbal tea.

When to call 112

• Someone has swallowed pennyroyal oil, even if they seem well. Call 112 or the Spanish poisons line, 91 562 04 20.
• A baby has had pennyroyal tea and is very drowsy, vomiting or having fits.
• Fits, fainting, confusion or vomiting blood.

Frequently asked questions about pennyroyal tea

Getting a medical assessment

If you have stomach problems that keep coming back, or questions about a herbal remedy, you can book a video consultation with Dr. Pedro Yelamo Vera, a physician registered in Spain. You can also read about heartburn and care in pregnancy. A prescription is never guaranteed: it is issued only where clinically appropriate after a genuine evaluation, as a private electronic prescription under Spanish law. This service is for urgent, non-emergency care. In an emergency, call 112.

This guide is general information. It does not replace the package leaflet or the advice of your doctor or pharmacist.