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8 Common Herbal Supplement & Medication Interactions to Look Out for

Over the last several years, many people have turned to herbal medicine to boost their immune systems, treat various diseases, and restore their overall health and well-being – me being one of them. In 2022 alone, the global herbal medicine market was valued at 166 billion dollars, and it is expected to reach 348 billion dollars by 2029! This shift towards natural herbal remedies is largely due to the perception that herbal supplements are more effective and safer than their synthetic counterparts. 

While it is true that herbal remedies are less likely to cause side effects and are often just as effective as their pharmaceutical equivalents, they do not come without risks. Particularly for those who take prescription and over-the-counter medications, consuming herbs with pharmaceuticals can increase the risk of negative interactions. I have worked with numerous clients who were unknowingly taking combinations of herbs and prescriptions that were negatively impacting each other. As a huge advocate for herbal remedies, my number one priority is to ensure that my clients are taking them properly and cautiously. Therefore, I have outlined the eight most common herbal supplements and their medication interactions. 

St. John’s Wort

Native to Europe, St. John’s wort is a plant with distinctive yellow, star-shaped flowers that is often touted for its anti-depressive benefits. In fact, it is equally as effective as antidepressant medications against mild and moderate depression. This herbal supplement may also help reduce menopausal symptoms—especially hot flashes. 

However, St. John’s wort is known to negatively interact with numerous prescription and over-the-counter medications. Specifically, it can weaken the effects of Xanax, Warfarin, antidepressants, birth control pills, cyclosporine, cancer medications, HIV drugs, statins, and heart medications such as digoxin and ivabradine. Therefore, if you are currently taking any of these medications, it is best to avoid using this herb.


Grown commercially in the Blue Ridge Mountains, goldenseal is one of the most commonly used herbal supplements in the U.S. Although more research is needed, it is often used to treat colds, hay fever, acne, eczema, conjunctivitis, and digestive discomfort. 

Similar to St. John’s wort, goldenseal should not be used in combination with most medications because it has been shown to inhibit the metabolism of over half of the currently used pharmaceuticals—including anticoagulant, antihypertensive, and antidiabetic medications. For example, a recent study found that goldenseal extract can decrease the level of metformin (a diabetes medication) in healthy adults by up to 25 percent. 

Black Cohosh  

Black cohosh was traditionally used by Native Americans to treat musculoskeletal pain, cough, fever, pneumonia, and irregular menstruation. Today, it is an incredible herbal remedy for the hot flashes and night sweats associated with menopause. There are also claims that it can alleviate menstrual pain and induce labor. 

Fortunately, it is among the few herbs with a low likelihood of interacting with medications. However, there are concerns that it could interact with over-the-counter and prescription medications, such as Allegra, glyburide, amiodarone, and statins. Therefore, it is best to consult your healthcare provider before you add it to your herbal regime. 


Ashwagandha is an Ayurvedic herb that has become increasingly popular for its ability to regulate stress and anxiety. It is one of my favorite adaptogenic herbs because it enhances the body’s resilience to stress by relieving adrenal dysfunction and lowering cortisol levels. Ashwagandha may also improve the quality and quantity of sleep for individuals with insomnia.

However, there is evidence that it may interact with diabetes, high blood pressure, immunosuppressant, sedative, thyroid, and anti-seizure medications. Ashwagandha may also increase testosterone levels; therefore, those with hormone-sensitive prostate cancer should steer clear of this herb.


Indigenous to the region east of the Rocky Mountains, echinacea has gained widespread recognition for its immune-enhancing properties. This medicinal coneflower was originally used by Native Americans to treat infections and wounds. But, current research supports its use to prevent the common cold. 

Though the risk of interactions between echinacea and most medications is low, there is evidence that it can potentially alter concentrations of certain antipsychotic and antidepressant medications. Echinacea has also been found to increase plasma levels of caffeine by blocking its metabolism.  

Asian Ginseng 

Asian ginseng has been used in traditional Chinese medicine for thousands of years. Similar to Ashwagandha, Asian ginseng is an adaptogenic herb that helps the body resist physical and psychological stress. It is also believed to improve physical stamina, concentration, memory, and immune function. 

But like most herbal remedies, Asian ginseng may interact with certain medications. Evidence has shown that it can decrease the effectiveness of medications, such as calcium channel blockers, statins, antidepressants, antihypertensives, and some chemotherapeutic and HIV agents. Asian ginseng may also affect the metabolism of the anticoagulant warfarin—but studies have yielded mixed results. 


Originally used by Pacific islanders for ceremonial and medicinal purposes, kava is revered for its anti-anxiety properties. Most clinical research shows that kava can specifically help to relieve non-psychotic anxiety symptoms. Due to its calming effects, kava extract may also reduce stress and insomnia.

Kava should not be taken with acetaminophen, nonsteroidal anti-inflammatory drugs, angiotensin receptor blockers, Glucotrol, glyburide, Avandia, warfarin, and proton pump inhibitors because it can inhibit the metabolism of these medications. In addition, those undergoing surgery are advised to stop taking kava five days before procedures that involve general anesthesia. Oral ingestion of kava can also increase the risk of drowsiness when taken with nervous system depressants like benzodiazepines or alcohol. 


Dating back to Ancient Greece and Rome, valerian was historically used to treat fatigue, migraines, and stomach pain. It is now used for insomnia, depression, anxiety, PMS, menopausal symptoms, and headaches. Because the evidence is inconsistent, the American Academy of Sleepy Medicine does not recommend taking valerian for chronic insomnia.

Nonetheless, valerian should not be consumed with alcohol or sedatives because of its potential sleep-inducing properties. The long-term use of valerian has not been researched extensively, but it is generally safe for most adults to use short-term. 


As always, please speak with your doctor before you begin taking any herbal supplement – or any supplement for that matter. If you are interested in learning more about herbal medicine and how it could benefit your health, book a one-on-one consultation with me here.



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