How Herbal Supplements Can Interfere with Medications

Since herbal supplements are often marketed as natural remedies for a variety of health conditions, many people mistakenly assume that these supplements are harmless. However, they can sometimes interfere with prescription and over-the-counter medications, sometimes with serious consequences. 

Certain herbal supplements can alter the way your body absorbs, metabolizes or responds to prescription drugs. This not only can lead to diminishing the drugs’ effectiveness, but it can also lead to harmful side effects in some cases. In this article, we’ll explore some of the most common herbal supplements and their resulting impact on medications.

What Are Herbal Supplements? 

Herbal supplements are often made from whole plants or parts of plants such as leaves, roots, seeds or flowers. Because they are derived from plants, they are often seen as “natural” alternatives. However, one should not underestimate their potent biological effects. Some herbs contain compounds that can interfere with the same bodily pathways as prescription and over-the-counter drugs, leading to unintended interactions. As such, herbal supplements should be treated with the same consideration as any medication, especially when using alongside other treatments. And always talk to your healthcare team before trying something new or adding something to your regimen. 

How Herbal Supplements Can Interfere with Medications

When adding herbal supplements into your diet, it’s crucial to understand how they can interact with your medications. We asked dietitians for their expert input on four common herbal supplements and their role in drug interaction.

Turmeric

A common herbal supplement that interferes with a number of medications is turmeric. Turmeric and its bioactive compound curcumin are recognized for their anti-inflammatory and brain health benefits. While turmeric is generally safe in small amounts from food, high doses from supplements could interfere with various medications, leading to significant health risks. 

Registered dietitian Bree Phillips, M.S., RD advises, “Turmeric may also lower blood sugar levels, potentially causing hypoglycemia when combined with diabetes medications like insulin or metformin.” The liver uses certain enzymes to process drugs, and turmeric can slow down these enzymes. As a result, medications might stay in your body longer than they should, which could increase the chances of side effects or even make the drug too strong. Additionally, Phillipps tells us, “Turmeric has blood-thinning properties that may amplify the effects of anticoagulants like warfarin, rivaroxaban and apixaban, increasing the risk of bleeding.”

Cinnamon

According to Sheila Patterson, RD, CDCES, while a small amount of cinnamon in your diet is usually fine, high doses or supplements could have a more noticeable effect. High doses of cinnamon can influence the liver’s ability to process various medications. Specifically, Cassia cinnamon, which is the form often found in supplements, contains a compound called coumarin, which can thin the blood. If you’re already taking prescription blood thinners like warfarin, aspirin or clopidogrel, adding cinnamon supplements could raise your risk of excessive bleeding or bruising. 

Similarly to the way turmeric can interfere with liver enzymes, Patterson warns, “Supplementing cinnamon can impact interactions with medications that the liver processes such as statins and acetaminophen.”

St. John’s Wort

St. John’s Wort has been touted for its use in a variety of conditions including depression and even wound healing. However, consumers should proceed with caution as this supplement can interact with several types of medications, leading to potential complications. 

St. John’s Wort can cause serotonin syndrome, a serious condition resulting from excessive serotonin levels, when combined with selective serotonin reuptake inhibitors (SSRIs). This is because a few of the compounds within St. John’s Wort also work to inhibit the reuptake of these neurotransmitters. Additionally, supplementing with St. John’s Wort can also reduce the effectiveness of birth control pills, immunosuppressants and blood thinners because it induces liver enzymes, which leads to an increase in the rate at which these drugs are broken down.

Echinacea

Echinacea, which people frequently use to support their immune system, can affect how some medications work in the body. Similarly to the other supplements we’ve discussed, supplementation of echinacea can change how the liver processes drugs, which might make them less effective. 

For those on immunosuppressants—medications that help prevent the body from attacking itself or rejecting a transplanted organ—echinacea’s effects might make these medications less effective. These medications work by dampening the immune system’s response to ensure it doesn’t target the transplanted organ or self-tissues. However, echinacea stimulates the immune system, which can counteract the intended effects of these drugs.

Tips for Including Herbal Supplements in a Healthy Way 

To ensure that you benefit from herbal supplements without compromising your health, it’s important to follow some key guidelines for their safe and effective use.

Consult a healthcare provider. 

Phillips advises, “To safely incorporate herbal supplements, it is essential to consult a healthcare provider. They can help determine the right dosage and assess potential risks or interactions to ensure the supplement supports your overall health.”

Choose third-party tested products

Phillips also recommends, “Because herbal supplements are not regulated by the Food and Drug Administration, it is important to choose products from a reputable brand and purchase from a trusted vendor.” To help ensure this, look for products with a third-party certification on their label (some common certifications include USP, Consumer Lab and NSF). Additionally, the potency of herbal supplements can vary widely, and their labels may not always reflect what’s inside the product. 

Consider timing.

Some supplements may be best taken with food, while others might be more effective on an empty stomach. It’s crucial to follow specific instructions for optimal absorption and effectiveness. And if you have questions about your specific supplement and medication regimen, talk to your healthcare team about the best schedule for you. 

The Bottom Line

Some herbal supplements—like turmeric, cinnamon, St. John’s Wort and echinacea—can interfere with how your body processes prescription and over-the-counter medications, leading to potential side effects or reduced drug efficacy. To navigate these interactions safely, it is crucial to consult with a healthcare provider before you start taking any new supplement. Choosing high-quality, third-party tested products and paying attention to timing and dosage will also help ensure that you reap the benefits of herbal supplements without compromising your health.