The healthiest cookies you’ll choose today

Our website uses cookies to collect useful information that lets us and our partners support basic functionality, analyze visitor traffic, deliver a better user experience, and provide ads tailored to your interests. Agreeing to the use of cookies is your choice. Learn more

Decline cookies Accept cookies
Skip to content
Fullscript leaf logo Sign in
Fullscript logo
Fullscript leaf logo
  • Our platform
    • Practitioner software
    • Pricing
    • Integrations
    • Patients on Fullscript
    • Book a demo
  • Learn
    • Spotlight
    • Protocols
    • Wellness blog
    • Practice resources
    • Webinars
    • Ingredient library
    • Practicing virtually
  • Support
    • Practitioner support
    • Patient help
    • Contact us
    • Or chat with us
Sign in Create account
Integrative Medicine
—

The Side Effects of Herbs and Supplements: What You Need to Know

March 14, 2023
Fact checked
Written by Kim Erickson
Medically reviewed by
Dr. Natacha Montpellier, ND, B.Sc.
  1. Wellness blog
  2. The Side Effects of Herbs and Supplements: What...

It’s no secret that dietary supplements are popular. In fact, more than 70% of Americans take at least one supplement every day. (38) And, according to the Office of Dietary Supplements, 29%—primarily older—people take four or more supplements daily. (18) Since herbs and dietary supplements can play an important role in supporting good health, their use can be beneficial. 

However, many people assume that, because herbs and supplements are natural, they are inherently safe. (34) And it’s true that many are. But side effects and drug interactions can and do occur. Although most side effects of herbs and supplements are typically mild, drug interactions can sometimes be serious or even life-threatening. (40)

Did you know? Prescription and non-prescription drugs are estimated to cause approximately 2,216,000 adverse reactions annually. (35) Yet, according to the American Association of Poison Control Centers, in 2020, fewer than 6.5% of those adverse reactions were caused by dietary supplements (including herbal supplements). (22)

side effects of herbs and supplements
Herbs, vitamins, minerals, and other nutrients are all considered dietary supplements.

What is the difference between herbal supplements and dietary supplements?

The U.S. Food and Drug Administration notes that “dietary supplement” is an umbrella term that covers natural products like vitamins, minerals, enzymes, and herbs. (36) 

In the United States, these products are regulated under the Dietary Supplement Health and Education Act of 1994. (13) According to the agency, a dietary supplement: 

  • Is a product taken by mouth that contains a dietary ingredient intended to supplement or enhance the diet
  • May include vitamins, minerals, herbs or other botanicals, amino acids, and substances such as enzymes, organ tissues, glandulars, and metabolites
  • Can be formulated as tablets, capsules, soft gels, gel caps, liquids, or powders (14)

While herbal supplements fall under the official definition of dietary supplements, they typically contain one or more medicinal herbs like ashwagandha or elderberry, and are used for the herb’s therapeutic properties. They are sold as tablets, capsules, powders, teas, extracts, and fresh or dried plants. (23)

Some dietary supplements that are designed to address a particular organ, bodily function, or health condition may contain a combination of targeted nutrients and herbs. 

Quality supplement plans in less than a minute

Try Fullscript

The benefits of herbal supplements and dietary supplements

Just like you can’t out-exercise a bad diet, you can’t out-supplement one either. That said, supplementing a healthy diet with vitamins, minerals, enzymes, and amino acids can be beneficial. For instance, studies suggest that dietary supplements can help to fill any nutritional gaps in the diet. (10)(15) They may also help prevent or manage certain health conditions. (8)(15)(39) Plus, research shows that taking targeted dietary supplements—including herbal supplements—can promote optimal health, longevity, and quality of life. (8)(39) However, problems can sometimes occur when supplements are taken in high doses or if you are also taking certain medications. 

Did you know? Herbal medicine was the primary type of medical care throughout the world before the advent of modern medicine. (34)

woman sitting on a couch holding her forehead
Although dietary supplements are generally safe, side effects such as headache or digestive upset can and do occur.

Side effects of herbs and supplements

Dietary supplements can enhance health when taken appropriately. But, when it comes to some nutrients, you can get too much of a good thing. According to researchers at the University of Maryland School of Medicine, the most common nutrients that can cause problems at high doses include biotin, copper, iron, niacin, vitamins A, D, and E, and zinc. (3)

In one study review conducted at the Mayo Clinic, people with extremely high blood concentrations of vitamin D ranging between 150 and 1220 ng/mL (an optimal concentration should be approximately 75 ng/mL) experienced symptoms of toxicity such as dehydration, loss of appetite, pain, and vomiting. (6)(19)

Supplementing with individual amino acids—a practice popular with athletes and bodybuilders—can also result in side effects. Not only can it cause an imbalance in the body’s amino acid concentrations, it can trigger dehydration, nausea, diarrhea, liver issues, muscle cramps, and water retention. (24)

10 common herb side effects 

Taking herbal supplements may result in side effects. While most are fairly mild, some can be of concern. Here are the most common side effects to look out for, as well as some of the herbs that may trigger these problems.

  1. Allergic reactions (chamomile, feverfew) (11)
  2. Bleeding (dong quai, garlic, Ginkgo biloba, white willow) (1)
  3. Dizziness (cat’s claw, kava, rhodiola) (7)(27)(37)
  4. Dry mouth (peppermint oil, St. John’s wort, valerian)  (33)(41)(43)
  5. Elevated blood pressure (non-deglycyrrhizinated licorice) (12)
  6. Headache (Asian ginseng, Ginkgo biloba, valerian) (4)(20)(43)
  7. Insomnia (Asian ginseng, feverfew, St. John’s wort) (4)(31)(41)
  8. Nausea and digestive upset (bacopa, echinacea, Ginkgo biloba) (2)(20)(16)
  9. Rash (dandelion, mugwort, yarrow) (32)
  10. Sun sensitivity (aloe, angelica, St. John’s wort) (5)(9)(41)
woman holding a supplement bottle using a laptop
If you take a prescription medication, always check for potential interactions before starting a new supplement.

Drug interactions with herbs and supplements

If you’re scheduled for surgery, your doctor will likely ask you to stop taking certain supplements a week or two before hitting the operating room as some can interfere with anesthesia (medications used to decrease or eliminate pain by putting a person to sleep) or could increase the risk of bleeding. (29) You may also be advised to avoid some herbs and nutrients if you’re prescribed certain medications. This is because some supplements can impact the absorption, breakdown, or removal of a particular drug. (30)

Some interactions between a supplement or food and certain drugs are well known. For instance, most people know that grapefruit and statin drugs (medications used to decrease cholesterol) don’t mix because the fruit or juice can cause too much of the drug to remain in the body instead of being broken down and removed from the body. (28) And it’s fairly common knowledge that you need to steer clear of St. John’s wort if you’re taking some antidepressants as it can lead to a life-threatening increase in serotonin levels (substance that contributes to feelings of well-being and happiness). (42) 

Other interactions, however, are less well known. For instance, goldenseal can potentially interact with a number of medications, including codeine (used to decrease pain), digoxin (used to treat heart conditions like heart failure), metformin (used to manage diabetes), and tamoxifen (used to treat breast cancer) (21)(25) And, according to research in the International Journal of STD & AIDS, several common supplements like calcium, iron, vitamin C, and zinc can decrease levels of antiretroviral drugs in the body (medications that treat viral infections). However, cat’s claw and evening primrose oil can increase the levels of these drugs in the body. (26)

Did you know? Adverse effects are more common in the older individuals and in people who are taking multiple prescription drugs. (17) 

The bottom line

Dietary and herbal supplements can be effective remedies and provide many health benefits. However, there can be side effects of herbs and supplements. While usually mild and short lived, some of these adverse effects can be serious. Of more concern, dietary supplements may interact with a myriad of prescription and over-the-counter medications, affecting drug absorption, concentration, and elimination. Because of these caveats, it’s smart to always check with your healthcare practitioner prior to taking any dietary supplement. This is especially important if you are currently taking a prescription drug or over-the-counter medication, or if you have an existing health problem.  

Quality supplement plans in less than a minute

Try Fullscript
References
  1. Abebe W. (2019). Review of herbal medications with the potential to cause bleeding: dental implications, and risk prediction and prevention avenues. The EPMA journal, 10(1), 51–64. 
  2. Aguiar, S. & Borowski, T. (2013). Neuropharmacological review of the nootropic herb Bacopa monnieri. Rejuvenation Research, 16(4), 313–326. 
  3. Anselmo, F. & Driscoll, M.S. (2021). Deleterious side effects of nutritional supplements. Clinical Dermatology, 39(5), 745-756. 
  4. Asian ginseng. (2020) National Center for Complementary and Integrative Health. https://www.nccih.nih.gov/health/asian-ginseng
  5. Bergamante, V., Ceschel, G.C., Marazzita, S., Ronchi, C., & Fini, A. (2007) Effect of vehicles on topical application of aloe vera and arnica montana components. Drug Delivery, 14, 7, 427-432.
  6. Bischoff-Ferrari, H.A. (2008). Optimal serum 25-hydroxyvitamin D levels for multiple health outcomes. Advances in Experimental Medicine and Biology, 624, 55-71. 
  7. Cat’s Claw. (2020) National Center for Complementary and Integrative Health.   https://www.nccih.nih.gov/health/cats-claw
  8. Chauhan, B., Kumar, G., Kalam, N., & Ansari, S.H. (2013). Current concepts and prospects of herbal nutraceutical: A review. Journal of Advanced Pharmaceutical Technology & Research, 4(1), 4–8. 
  9. Committee on Herbal Medicine Products. (2007). Reflection paper on the risks associated with furocoumarins contained in preparations of Angelica archangelica L. European Medicines Agency. https://www.ema.europa.eu/en/documents/scientific-guideline/final-reflection-paper-risks-associated-furocoumarins-contained-preparations-angelica-archangelica-l_en.pdf
  10. Cowan, A.E., Jun, S., Tooze, J.A., Eicher-Miller, H.A., Dodd, K.W., Gahche, J.J., Guenther, P.M., … Bailey, R.L. (2019). Total usual micronutrient intakes compared to the dietary reference intakes among U.S. adults by food security status. Nutrients, 12(1), 38. 
  11. Denisow-Pietrzyk, M., Pietrzyk, Ł. & Denisow, B. (2019). Asteraceae species as potential environmental factors of allergy. Environmental Science and Pollution Research, 26, 6290–6300.
  12. Deutch, M.R., Grimm, D., Wehland, M., Infanger, M., & Krüger, M. (2019). Bioactive candy: Effects of licorice on the cardiovascular system. Foods (Basel, Switzerland), 8(10), 495. 
  13. Dietary supplement health and education act of 1994. Public Law 103-417:103rd Congress. National Institutes of Health: Office of Dietary Supplements. https://ods.od.nih.gov/About/DSHEA_Wording.aspx
  14. Dietary supplements: questions and answers. (2015). U.S. Food & Drug Administration. https://www.fda.gov/drugs/frequently-asked-questions-popular-topics/dietary-supplements-questions-and-answers
  15. Dietary supplements: What you need to know. (2020). National Institutes of Health, Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/WYNTK-Consumer/
  16. Echinacea. (2020) National Center for Complementary and Integrative Health. https://www.nccih.nih.gov/health/echinacea
  17. Felix, T.M., Karpa, K.D., & Lewis, P.R. (2015). Adverse effects of common drugs: dietary supplements. FP Essentials, 436,31-40. 
  18. Gahche, J.J., Bailey, R.L., Potischman, N., & Dwyer, J.T. (2017). Dietary supplement use was very high among older adults in the United States in 2011-2014. The Journal of Nutrition, 147(10), 1968–1976. 
  19. Galior, K., Grebe, S., & Singh, R. (2018). Development of vitamin D toxicity from overcorrection of vitamin D deficiency: A review of case reports. Nutrients, 10(8), 953. 
  20. Ginkgo, (2020) National Center for Complementary and Integrative Health. https://www.nccih.nih.gov/health/ginkgo
  21. Goldenseal. (2021) National Center for Complementary and Integrative Health. https://www.nccih.nih.gov/health/goldenseal
  22. Gummin, D.D., Mowry, J.B., Beuhler, M.C., Spyker, D.A., Bronstein, A.C., Rivers, L.J., Pham, N.P.T., & Weber, J. (2021). 2020 annual report of the American Association of Poison Control Centers’ National Poison Data System (NPDS): 38th annual report. Clinical Toxicology (Philadelphia), 59(12),1282-1501. 
  23. Herbal medicine. (2017). MedlinePlus. https://medlineplus.gov/herbalmedicine.html
  24. Holeček M. (2022). Side effects of amino acid supplements. Physiological Research, 71(1), 29–45. 
  25. Horn, J.R. & Hansten, P.D. (2012). Goldenseal drug interactions. Pharmacy Times, 79(9).
  26. Jalloh, M.A., Gregory, P.J., Hein, D., Risoldi Cochrane, Z., & Rodriguez, A. (2017). Dietary supplement interactions with antiretrovirals: a systematic review. International Journal of STD and AIDS, 28(1), 4-15. 
  27. Kava. (2020) National Center for Complementary and Integrative Health.     https://www.nccih.nih.gov/health/kava
  28. Lee, J.W., Morris, J.K., & Wald, N.J. (2016). Grapefruit juice and statins. American Journal of Medicine, 129(1):26-29.  
  29. Levy, I., Attias, S., Ben-Arye, E., Goldstein, L., Matter, I., Somri, M., & Schiff, E. (2017). Perioperative risks of dietary and herbal supplements. World Journal of Surgery, 41(4):927-934.
  30. Mixing medications and dietary supplements can endanger your health. U.S. Food & Drug Administration. https://www.fda.gov/consumers/consumer-updates/mixing-medications-and-dietary-supplements-can-endanger-your-health
  31. Pareek, A., Suthar, M., Rathore, G.S., & Bansal, V. (2011). Feverfew (Tanacetum parthenium L.): A systematic review. Pharmacognosy Reviews, 5(9), 103–110. 
  32. Paulsen E. (2017). Systemic allergic dermatitis caused by sesquiterpene lactones. Contact Dermatitis, 76(1):1-10.
  33. Peppermint oil. (2020) National Center for Complementary and Integrative Health. https://www.nccih.nih.gov/health/peppermint-oil
  34. Phua, D.H., Zosel, A., & Heard, K. (2009). Dietary supplements and herbal medicine toxicities-when to anticipate them and how to manage them. International Journal of Emergency Medicine, 2(2), 69–76. 
  35. Preventable adverse drug reactions: a focus on drug interactions. (2018). U.S. Food & Drug Administration. https://www.fda.gov/drugs/drug-interactions-labeling/preventable-adverse-drug-reactions-focus-drug-interactions
  36. Questions and answers on dietary supplements. U.S. Food & Drug Administration. https://www.fda.gov/food/information-consumers-using-dietary-supplements/questions-and-answers-dietary-supplements
  37. Rhodiola. (2020) National Center for Complementary and Integrative Health. https://www.nccih.nih.gov/health/rhodiola
  38. Ronis, M., Pedersen, K. B., & Watt, J. (2018). Adverse effects of nutraceuticals and dietary supplements. Annual Review of Pharmacology and Toxicology, 58, 583–601. 
  39. Sachdeva, V., Roy, A., & Bharadvaja, N. (2020). Current prospects of nutraceuticals: a review. Current Pharmaceutical Biotechnology, 21(10),884-896.
  40. Should you take dietary supplements? (2013). NIH News in Health. https://newsinhealth.nih.gov/2013/08/should-you-take-dietary-supplements
  41. St. John’s wort. (2020) National Center for Complementary and Integrative Health. https://www.nccih.nih.gov/health/st-johns-wort 
  42. St. John’s Wort and Depression: In Depth. (2017) National Center for Complementary and Integrative Health. https://www.nccih.nih.gov/health/st-johns-wort-and-depression-in-depth
  43. Valerian. (2020) National Center for Complementary and Integrative Health.https://www.nccih.nih.gov/health/valerian
  • Print
  • Email
  • Facebook
  • LinkedIn
  • Twitter
  • Pinterest

Disclaimer

The information in this article is designed for educational purposes only and is not intended to be a substitute for informed medical advice or care. This information should not be used to diagnose or treat any health problems or illnesses without consulting a doctor. Consult with a health care practitioner before relying on any information in this article or on this website.

Cancel reply

Your email address will not be published. Required fields are marked *

Prev Next
Back to main wellness blog page

Get more resources for your practice

Protocols
Practice resources
Ingredient library
Webinars

Share

  • Print
  • Email
  • Facebook
  • LinkedIn
  • Twitter
  • Pinterest

Fullscript content philosophy

At Fullscript, we are committed to curating accurate, and reliable educational content for practitioners and patients alike. Our educational offerings cover a broad range of topics related to integrative medicine, such as supplement ingredients, diet, lifestyle, and health conditions.

Medically reviewed by expert practitioners and our internal Integrative Medical Advisory team, all Fullscript content adheres to the following guidelines:

  1. In order to provide unbiased and transparent education, information is based on a research review and obtained from trustworthy sources, such as peer-reviewed articles and government websites. All medical statements are linked to the original reference and all sources of information are disclosed within the article.
  2. Information about supplements is always based on ingredients. No specific products are mentioned or promoted within educational content.
  3. A strict policy against plagiarism is maintained; all our content is unique, curated by our team of writers and editors at Fullscript. Attribution to individual writers and editors is clearly stated in each article.
  4. Resources for patients are intended to be educational and do not replace the relationship between health practitioners and patients. In all content, we clearly recommend that readers refer back to their healthcare practitioners for all health-related questions.
  5. All content is updated on a regular basis to account for new research and industry trends, and the last update date is listed at the top of every article.
  6. Potential conflicts of interest are clearly disclosed.
Read more
Fullscript logo

We're certified carbon-neutral. It's part of our commitment to helping people get better.

American flag - toggles to show american specific contentUnited States
Canadian flag - toggles to show canada specific contentCanada
Product
  • Practitioner software
  • Integrations
  • Pricing
  • Patients
  • Supplement quality
  • Treatment adherence
  • Catalog
  • Wholesale
Company
  • Spotlight
  • About Fullscript
  • Collective
  • Leadership
  • Culture guide
  • Careers
  • Engineering
  • News
Support
  • Practitioner support
  • Patient help
  • Testimonials
  • General FAQ
  • Patient shipping
  • Wholesale shipping

© Fullscript 2023. All rights reserved.

*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.

  • Privacy Statement
  • Terms of Service
  • Accessibility Policy
  • Customer Support Policy
  • Acceptable Use Policy
  • California Privacy Notice
Send this to a friend