Herbal Supplements During Cancer Treatment: Are Supplements Helpful or Harmful?

Herbal Supplements During Cancer Treatment

Are Suppliments Helpful or Harmful?

Herbal supplementsHerbs = natural = healthy, right?

Well, it’s not all black and white. While there are many pharmacological benefits to natural substances, there is potential for harmful drug interactions if someone is on a potent cancer treatment like chemotherapy. 

Additionally, the United States Food and Drug Administration (FDA) does not regulate safety or labels before they get on the shelves, so it’s hard to be sure what you’re consuming. The potencies of herbal supplements can also vary greatly depending on harvesting.  

None of this information is apparent, which is why July is Herbal and Prescription Interaction Awareness Month. Here to Serve wants to help bring awareness to this vital topic and empower you to share this information with others in your cancer circle. Of course, it’s essential to talk to your doctor regarding your or your child’s care plan and what supplements may or may not be appropriate.  

Herbs can change the way drugs metabolize 

Many herbs change the way a drug processes in the body. For example, if an herb increases the metabolism of a drug, it can reduce its concentration in the blood and its effectiveness. Meanwhile, decreased drug metabolism can increase the drug’s concentration in the blood, potentially leading to increased side effects. Additionally, herbs can raise or lower blood pressure, increase blood thinning and thereby the risk of bleeding, and change how your body reacts to sedation or general anesthesia.  


What’s safe vs unsafe?  

There are not sufficient data regarding most drug and herbal supplement Interactions. In fact, so many of their effects and reactions remain unclear and inconsistent. This can make navigating this part of the treatment process overwhelming and confusing. However, here’s some of what we do know:  

  • Avoid all supplements when starting treatment or surgery. It’s typically recommended to stop taking herbal remedies and other dietary supplements one or more weeks before having surgery or starting treatment 
  • Avoid antioxidants. Data varies about the use of antioxidants, like vitamin C. While some data suggests it can kill cancer cells or protect healthy cells, these supplements may also make these treatments less effective. Until more is known, it’s best to avoid them during treatment 
  • Spices used for cooking are generally safe. However, if you cook with a spice often or in large amounts, check with your doctor to ensure that it doesn’t interact with treatment. For example, garlic has been associated with postoperative hemorrhage as well as interaction with anticoagulants 
  • Some herbs are associated with greater drug-to-drug interactions. Particular parts of foods and supplements can alter the PK of specific types of drugs. This includes St. John’s wort, grapefruit juice, and epigallocatechin gallate from green tea 
  • Herbs can help alleviate treatment side effects. Talk to your doctor about supplements that can assist certain symptoms. For example, ginger may help nausea, and Astragalus has been shown to reduce adverse reactions to chemotherapy 

Want to look up a specific herb? Memorial Sloan Kettering Cancer Center has a database where you can search by herb and if there are any known drug-to-drug interactions. Of course, always check with your healthcare provider before incorporating any supplements into your or your child’s diet.  

Get answers and help from Here to Serve

There is so much along the cancer journey that can feel overwhelming and confusing. Here to Serve is available to help lessen this burden on families. We provide resources on topics such as nutrition and other hard-to-find resources that may become more relevant to families at any point in the cancer journey. Learn more about the services from Here to Serve, and get help today if you or someone you know needs extra care.

Author: Emily Rogalin 

Connect with Emily on LinkedIn. Emily Rogalin is a copywriter in healthcare advertising in NYC. Having lost multiple members in her family to cancer, she is honored to help bring support to families on this difficult journey.

This blog has been updated from its original post in 2021 

Information on the Here to Serve website is for educational and informational purposes only. Please consult a medical professional for specific medical guidance. 


Memorial Sloan Kettering Cancer Center