Peppermint Interactions Overview

Do Peppermint Supplements Have Any Drug Interactions?

While peppermint oil is generally considered safe to use, it does have some potential drug interactions important to be aware of.

Below is some general oil regarding potential peppermint interactions. We have all these interactions documented in more detail on our individual drug-herbal interaction pages.

Interaction with Cyclosporine

Peppermint oil may increase the levels and adverse effects of cyclosporine, a medication commonly used to prevent organ rejection after transplantation.

Animal research suggests that peppermint oil inhibits cyclosporine metabolism, but this interaction has not been reported in humans.

If you take cyclosporine, it is recommended to be cautious when using peppermint oil.

Interaction With Cytochrome P450 1A2 (CYP1A2) Substrates

Peppermint oil may increase the levels of CYP1A2 substrates, which are medications metabolized by the enzyme CYP1A2 in the liver.

While in vitro (i.e., in a lab) and animal research suggests that peppermint oil inhibits CYP1A2, clinical research shows that peppermint tea did not significantly affect the metabolism of caffeine, a CYP1A2 substrate.

More research is needed to confirm this interaction but it appears to be clinically insignificant.

Examples of CYP1A2 substrates include:

• Caffeine
• Clozapine
• Duloxetine
• Fluvoxamine
• Melatonin
• Ropinirole
• Tacrine
• Tizanidine
• Theophylline
  

Interaction with Cytochrome P450 2C19 (CYP2C19) Substrates

Peppermint oil may increase the levels of CYP2C19 substrates, which are medications metabolized by the enzyme CYP2C19 in the liver.

In vitro research suggests that peppermint oil inhibits CYP2C19, but this interaction has not been reported in humans.

More studies are needed but it is unlikely that this is a clinically significant interaction.

Examples of CYP2C19 substrates include:

• Citalopram
• Diazepam
• Omeprazole
• Phenytoin
• Propranolol
• Sertraline
  

Interaction with Cytochrome P450 2C9 (CYP2C9) Substrates

Peppermint oil may increase the levels of CYP2C9 substrates, which are medications metabolized by the enzyme CYP2C9 in the liver.

In vitro research suggests that peppermint oil inhibits CYP2C9, but this interaction has not been reported in humans and it is assumed to be unlikely to occur.

Examples of CYP2C9 substrates include:

• Warfarin
• Phenytoin
• Celecoxib
  

Interaction with Cytochrome P450 3A4 (CYP3A4) Substrates

Peppermint oil may increase the levels of CYP3A4 substrates, which are medications metabolized by the enzyme CYP3A4 in the liver.

Clinical research in healthy volunteers suggests that a single dose of peppermint oil inhibits CYP3A4 enzymes and increases the AUC of felodipine, a CYP3A4 substrate.

However, in vitro research suggests that peppermint oil only inhibits CYP3A4 at very high concentrations.

The dosages used in supplements are unlikely to cause an interaction, but it is nevertheless important to be aware of.

Examples of CYP3A4 substrates include:

• Simvastatin
• Clarithromycin
• Atorvastatin
• Cyclosporine
• Tacrolimus
• Midazolam
• Sildenafil
  

Interaction with Iron Supplements

Peppermint oil may inhibit the absorption of iron supplements, reducing their effectiveness.

If you take iron supplements, it is recommended to avoid the concomitant use of peppermint. It is important to inform your healthcare provider of all medications and supplements you are taking, including peppermint oil, to avoid potential interactions and side effects.

Are Peppermint Supplements Standardized?

While different manufacturers use different standardizations for their supplements, peppermint is generally standardized in some way when manufactured in supplement form.

Peppermint oil is a mixture of different compounds, with the major compounds being menthol, menthone, and menthyl acetate. 'Pharmaceutical grade' peppermint oil generally contains at least 44% menthol.

It is important to note that peppermint oil can also contain a substance called pugelone, which can be harmful in high concentrations. Young peppermint leaves have higher concentrations of pugelone than mature leaves.

To ensure safety, peppermint oil products should contain less than 1% pugelone, and some manufacturers use methods to reduce the amount of this substance.

Lastly, many peppermint oil supplements have modified release systems, designed to dissolve in a particular part of the gastrointestinal tract.

For example, one peppermint oil product that has been studied in clinical trials is called IBgard. It is designed to release the oil slowly in the small intestine, using a triple-coated capsule with a solid form of peppermint oil inside.

Drugs that interact with Peppermint