Are You Aware of These 10 Drug-Herb Interactions?

By Guest Contributor Leondria Taty, MSN, FNP-C

Within the past 24 hours, you’ve probably consumed an herb and didn’t even know it. Think about it – almonds (Prunus Amygdalus), cinnamon (Cinnamomum verum), ginger (Zingiber officinale), cayenne (Capsicum annuum), grapes/grape seed (Vitis Vinifera), tomatoes (Lycopersicon esculentum), goji (Lycium barbarum), soy (Glycine max), and many others like it all derive from an herbal plant. Studies support the myriad of health benefits that herbs can provide, many of which have little to no side effects. 

Hence, consumer demand has grown with many questioning the efficacy and safety of prescription drugs. Many now prefer a more “natural” approach to healthcare. So it’s no wonder that herbal therapy is a constant trend in the complementary and alternative medicine market.

With that said, it’s highly likely that you’re providing care for patients that have either taken herbal supplements, are taking them, or are considering herbal remedies. Are you assessing for herbal use during history taking? Do you ever consider the effects of herbal intake in your list of differential diagnoses? Do you feel prepared to discuss herbal therapy during patient education? For the record, most medical professionals do not, namely because education about herbal therapy is deficient during medical training. This could pose as a major problem, considering that some herbs interact dangerously with prescription medications. There’s a lot to know about the potential risks of herbal supplement use, and knowing about all of them is unrealistic. But if you had to start somewhere, start with these 10 common herb-drug interactions:

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1. Hawthorn (Crataegus monogyna) – Hawthorn is taken to support heart-related disorders. Ironically, this herb can also cause many cardiac problems when taken with beta blockers, calcium channel blockers, nitrates, and digoxin.

2. Evening Primrose Oil (Oenothera biennis) – Primrose oil is particularly popular for women’s health related conditions. However, with blood thinners and first generation antipsychotics, this herbal supplement can increase bleeding and seizure risk.

3. Ginkgo (Ginkgo Biloba) – Credited with mental function improvement, this herbal supplement has the potential to increase bleeding risk when taken with blood thinners.

4. Green Tea Extract (Camellia sinensis L.) – This popular herbal extract boasts many benefits like increased energy, cholesterol reduction, cancer, and weight loss. However, green tea extract can also be hepatotoxic, therefore it negatively interacts with a lot of drugs – stimulants, certain antibiotics, and estrogen-containing medication are just a few.

5. Kava (Piper methysticum) – Primarily used for its anxiety reducing ability, Kava has been associated with hepatotoxicity and liver failure. Taking it with sedatives is a major contraindication.

6. Kratom (Mitragyna speciosa) – Kratum is taken to self-treat opioid withdrawal. There have been cases of respiratory depression, psychosis, seizures, and even death with using the herb. Worsening depression and possible fatal interactions can occur when taken with opioids, alcohol or illegal drugs.

7. St. John’s Wort (Hypericum perforatum) – St. John’s Wort has a reputation for alleviating mild to moderate depression. Be reminded that concurrent use with antidepressants can cause serotonin syndrome. It can also reduce the efficacy of oral contraceptives and many other drugs.

8. Ginseng (Panax ginseng) – Ginseng is marketed to alleviate a number of conditions, like erectile dysfunction and for cancer prevention. However, ginseng use can decrease warfarin levels and cause serious interactions with some antidepressants and anticancer drugs, increase digoxin levels, and can further lower glucose levels in those taking hypoglycemic drugs.

9. Flaxseed (Linum usitatissimum) – The fiber in this herb contributes to its lipid lowering capabilities. Therefore, concurrent use with laxatives and stool softeners should be avoided. Flaxseed also binds with drugs like digoxin, preventing absorption of the medication.

10. Garlic extract (Allium sativum) – People use this garlic for the treatment and prevention of arteriosclerosis. Because it inhibits clotting function, garlic should be used with caution in those with clotting disorders, awaiting surgery, or who take blood thinners.

It can be overwhelming to keep up with the number of herbal supplements available on the market as well as their potential for interaction with pharmaceutical medications. The most important step for nurse practitioners to take is to ask patients about herbal use. Several online directories, such as the NIH Medline Plus Herbs and Supplements Directory, list herb-drug interactions and are a valuable resource. You might also consider developing a consultative and/or referral relationship with a reputable and professionally credentialed medical herbalist in the community you serve. Look for herbalist that received certification from peer-reviewed organizations.


About the Author: Leondria Taty is an advanced practice registered nurse with board certification as a Family Nurse Practitioner and as a Holistic Nurse. Her clinical experience is in public health. Leondria also works as an adjunct clinical faculty member at the University of South Alabama. 


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