My herbal tea can do that? Herbal interactions with medicine

Posted: November 7, 2012 in What is ... ?
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Photo Credit: nuchylee via

By Shelly Najjar

What is herbal tea?

Regular tea (such as black, white, oolong, and green teas) are drinks made by soaking the leaves of the tea plant (called Camellia sinensis) in water. The leaves are strained out and the water is consumed.

Herbal teas are drinks made from plants (and plant parts) other than the tea plant, soaked in water. The water is consumed but the wet plants are strained out.

Common plants used in herbal tea include

  • Mint
  • Chamomile
  • Licorice root
  • Orange peel
  • Cinnamon (and other spices)
  • Ginger
  • Vanilla
  • Berries
  • Lemongrass
  • Rosehips
  • Other flowers

Herbal teas do have many benefits, and often people drink them for their medicinal properties. Many herbal teas contain antioxidants, which are lower the risk for developing chronic diseases like heart disease and cancer.

However, because they do have medicinal properties, they can often interact with prescription and over-the-counter medications.

Potential problems

Both regular teas and herbal teas (and other herbal supplements) contain compounds that can interact with medications. Some of these interactions enhance the action of the drug, and some of them decrease the action of the drug. Interactions between herbs (which are regulated like food) and medications are called food-drug interactions.

Why is this important?

Medications are given in specific doses based on how they are expected to act in the body. Regular and herbal teas can affect how a drug acts in the body at a certain dose.

For example, if you are taking Coumadin (or warfarin, or aspirin: anticoagulants/blood thinners to prevent blood clots) and you also are drinking chamomile tea (which can interfere with anti-clotting medications), you could end up with not enough clotting action (a little clotting ability is healthy and necessary to stop bleeding if you get a cut, etc.).

It is very important to talk with your health care provider (especially pharmacists) about all the medications and herbal supplements you consume, including regular and herbal teas. In addition, make sure you know what foods and herbs can interact with the medications you take.

Common interaction warnings

Here are a few herbs that can have the potential to interact with medications. Sources: Natural Standard and UMMC’s CAM Index (see Resources, below)

Note: This is not a complete list. You and your healthcare team are responsible for checking your medications for interactions (also see site Disclosure).

  • Licorice root – Licorice should be avoided or consumed with caution if you are taking ACE inhibitors, diuretics, digoxin, aspirin, corticosteroids, insulin, oral contraceptives, or laxatives. These recommendations are based on animal and human studies, case studies, and expert opinion based on the known effects of licorice.
  • Peppermint – One of the most commonly reported side effects of peppermint is that it causes heartburn. Peppermint can relax the lower esophageal sphincter (the par t of the body that keeps food from going out of the stomach back up into your esophagus, which is the tube the food goes down), especially in people with gastroesophageal reflux disease (GERD), despite medications to prevent this from happening.
  • Ginger – The common warning for ginger is to avoid when taking anticoagulants, based on animal studies and human case studies, where ginger has been shown to have similar properties. Taking both ginger and anticoagulant drugs may cause too much bleeding; however, scientific evidence is limited
  • Chamomile – The usual warning for chamomile is to avoid taking it with sedatives (including alcohol) and anticoagulant medication, based on animal and human studies, because of evidence that it can increase drowsiness and may interact with blood clotting. Chamomile also may have some effect on certain drugs like oral contraceptives and statins that are broken down in the liver, based on in vitro studies.


Here are some resources to find out if you may have a potential interaction.

Note: This is not a complete list. You and your healthcare team are responsible for checking your own medications, using resources not limited to those mentioned here.

  • Pharmacist and integrative pharmacist
  • Food-drug interaction books – lists drugs and the interactions they can have with foods and herbal supplements. My recommendation is Food-Medication Interactions. It’s a resource I used a lot in my nutrition classes, at the undergraduate and graduate levels, and even now in various projects and jobs. If you want to help support me and this blog, click this version of the link that (at no extra cost to you) will give me a very small portion of any Amazon purchase you make in the next 24 hours. If you don’t want to help me in this way, use the first link.
  • Natural Medicines (formerly Natural Standard) – evidence-based resource that reviews complementary and alternative medicines and their uses, effectiveness, side effects, and interactions; some information is only available to subscribers, but you may have access through your local or university libraries
  • Complementary and Alternative Medicine Index from U of Maryland Medical Center – includes descriptions of treatments, side effects, and interactions
  • National Center for Complementary and Alternative Medicine (NCCAM) – safety and effectiveness information, fact sheets, resources, and tips for choosing, using, and reporting alternative therapies use to healthcare providers
  • “When Foods and Drugs Collide — Studies Expose Interactions Between Certain Foods and Medications” interesting article, at the very bottom it has a table of potential food-drug interactions
  • 5 Common Food-Drug Interactions – a dietitian interviews a pharmacist to explain 5 of the most common interactions to be aware of

Note: Regular and herbal teas can also be harmful in certain medical conditions including pregnancy, and you should talk with your healthcare provider and Registered Dietitian if you have any existing medical condition.

(Special Thanks: This post was inspired by 1digitalfingerprint, who wrote a post on herbal tea in September, and suggested I expand my comment on interactions into a full post.)

Shelly Najjar, MPH, RDN is a Registered Dietitian Nutritionist and editor of Nutrition Nuts and Bolts. You can find her on Twitter (@ShellyNajjar), LinkedIn, and at

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  1. Irene Harris says:

    Hi. May I know whether Lemon Grass tea interact with statin(cholesterol lowering medication).
    I would appreciate your reply. Thank you.

    • Hi Irene, thanks for your question. According to Natural Medicines, a peer reviewed resource for health professionals and the public, there are no known interactions between lemongrass and any drugs; however, you should double check this information with your pharmacist as I do not know your full medical situation. Thanks for reading! -Shelly
      (This blog is for informational/educational purposes and not intended to modify an individual’s treatment plan. Please see full disclosure for more information).

  2. […] has many health benefits, but it can also have some very serious interactions with medications. In this Nutrition Nuts and Bolts post, I review potential problems and give you some resources you can use to find out if your herbal […]

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  4. […] has many health benefits, but it can also have some very serious interactions with medications. In this Nutrition Nuts and Bolts post, I review potential problems and give you some resources you can use to find out if your herbal […]

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