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Herbal teas—made by soaking the roots, stems, flowers, and other plant components in hot water— have been used for centuries as natural remedies for various ailments. They contain antioxidants and other beneficial plant compounds that may help with anxiety, sleep quality, and digestion, among other health conditions.
Despite the potential benefits of sipping a daily cup of tea, some herbal teas, such as chamomile, St. John’s wort, and kava tea, may interact with your medications by changing their absorption, metabolism, and excretion.
1. Ginkgo Biloba Tea
Ginkgo biloba is one of the most popular herbal supplements in the United States. Although extremely limited, some data suggest it may help reduce symptoms of anxiety, age-related cognitive decline, and high blood pressure.
However, the herb contains compounds that may slow blood clotting. Consuming ginkgo biloba tea combined with blood thinners such as warfarin and non-steroidal anti-inflammatory drugs (NSAIDs) like aspirin and ibuprofen, which also slow blood clotting, may increase the risk of bruising and bleeding.
Additionally, consuming ginkgo biloba alongside certain anti-depressants may increase the risk of serotonin toxicity.
2. St. John’s Wort Tea
St. John’s wort (Hypericum perforatum) is a plant with yellow flowers that, according to research, may be effective at treating mild to moderate depression.
Data suggests the herb may work similarly to selective serotonin reuptake inhibitors (SSRIs) by increasing levels of serotonin, dopamine, and noradrenaline. These brain chemicals help lift and regulate your mood.
When combined with traditional antidepressants, St. John’s Wort can lead to a rare but life-threatening condition called serotonin syndrome that occurs when serotonin levels get too high.
St. John’s Wort tea may also interfere with the effectiveness of other medications, including:
- Birth control pills
- Medications used to treat human immunodeficiency virus (HIV), cancer, and heart conditions
- Pain medications
- Immunosuppressants (help prevent your body from attacking healthy tissue and cells)
- Blood thinners
- The allergy medication Allegra (fexofenadine)7
3. Chamomile Tea
Chamomile tea is commonly used to calm anxiety and help promote better sleep. While the herb is generally considered safe when used in the amounts typically found in tea, there are some potential medication interactions to be aware of.
There have been some reports of chamomile interacting with the blood thinner warfarin, as well as cyclosporine, a medication used to prevent organ rejection after transplant.8
4. Ginger Tea
Ginger tea, made by steeping fresh ginger root in water, is most commonly sipped to treat nausea and vomiting. Evidence suggests the herb may also help improve digestion, menstrual pain, and inflammation.
Most of the supposed health benefits of ginger come from compounds called gingerols and shogaols. Like many other herbal teas, ginger tea may increase the risk of bleeding when combined with blood-thinning medications.
5. Valerian Root Tea
Valerian tea is an herbal tea made from the dried roots, stems, and rhizomes of the valerian plant (Valeriana officinalis). It has a strong, pungent odor that some people find unpleasant.
Valerian root contains multiple chemical compounds, including valepotriates and sesquiterpenes, which may be responsible for the herb’s mild sedative and tranquilizing effects.12
Many people drink valerian root tea to help with sleep, depression, anxiety, and menstrual cramps, though further research is needed to confirm these benefits.13
Because of valerian’s sedating effect, it may increase the effect of sedatives and other medications and supplements with similar properties. These include:14
- Benzodiazepines, including Xanax (alprazolam), Valium (diazepam), and Ativan (lorazepam)
- Barbiturates, or central nervous system depressants, such as morphine and Diprivan (propofol)
- Dietary supplements, including melatonin and kava
6. Goldenseal Tea
Goldenseal (Hydrastis canadensis) is a perennial herb native to North America. Its leaves are often used to make tea because they’re less bitter than the root.
Today, many people consume goldenseal tea as a natural remedy for colds, ulcers, respiratory tract infections, and digestive problems.
Goldenseal has the potential to interact with diabetes medications, including metformin. A study found that goldenseal extract combined with metformin decreased metformin levels by as much as 25%, increasing the risk of hyperglycemia (high blood sugar).15
Note that goldenseal extract is a much more concentrated form of goldenseal.
7. Kava Tea
Kava (Piper methysticum) is a member of the pepper family that has been used for years to treat everything from anxiety to insomnia. However, despite some evidence linking kava to a slight reduction in anxiety, the herbal supplement has been associated with a risk of severe liver injury. Combining kava with alcohol or Tylenol (acetaminophen) may increase this risk.
Most of the literature on kava and its drug interactions examine kava extract, not tea specifically, so there’s a chance kava tea might not interact in the same way with these supplements and drugs.
Kava may interact with several medications, including:
- Sedatives and sleep aids
- Medicines used to treat Parkinson’s disease
- Muscle relaxants
- Benzodiazepines used to treat anxiety
- Monoamine oxidase inhibitors (MAOI) antidepressants
- SSRI antidepressant medications
- Anti-cancer medications
- Birth control pills
- Anesthesia
Written by Lindsey DeSoto, RD. Medically reviewed by Barbie Cervoni, RD (health.com)
