Herbal Teas That Can Affect Your Medications

Some popular herbal teas can interact with medications. Teas made with herbs such as St. John’s wort, ginkgo biloba, chamomile, ginger, valerian root, kava and ashwagandha may affect how certain prescription or over-the-counter medicines work in the body.

That does not mean every herbal tea is unsafe. But it does mean “natural” does not always mean risk-free. This is especially true if you take medications for heart disease, blood pressure, blood clots, depression, anxiety, diabetes, sleep, immune conditions or chronic pain.

If you drink herbal tea occasionally, it may feel like a simple wellness habit. But herbs contain active compounds. In some cases, those compounds can increase side effects, reduce a medication’s effectiveness or change how quickly your body processes a drug.

If you have concerns about how an herbal tea may interact with any medications you’re taking, it’s a good idea to talk with your doctor or pharmacist before adding a new herbal tea to your routine, especially if you drink it daily or use it for a specific health purpose.

How does herbal tea affect medication?

Herbal teas may affect medication because the plants used to make them can contain compounds that can affect your body in several ways.

Absorption

Some herbs may change how a drug is absorbed. This can affect how much medication enters your bloodstream.

Metabolization

Some herbs may change how a drug is metabolized. This means the herb may speed up or slow down the way your liver or other systems break down the medication.

Excretion

Some herbs may change how a drug is excreted. This can affect how quickly the medication leaves your body.

Additive effects

Some herbs may amplify the effects of certain medications . For example, an herb that causes drowsiness may increase the sedating effect of a sleep medication. An herb that affects clotting may increase bleeding risk when combined with a blood thinner.

Antagonistic effects

Some herbs may work against a medication. For example, an herb may lower the amount of medication in your body, making the medication less effective.

Unintended side effects

Some may increase side effects, such as bleeding, drowsiness, changes in blood pressure, changes in blood sugar, or serotonin-related symptoms.

Because these interactions can be hard to predict, the safest approach is to ask a clinician or pharmacist before making herbal teas part of your daily routine.

Risk factors

Your individual risk factors for an adverse reaction depend on several things, including:

• The type of herb in the tea
• How much you drink
• How often you drink it
• The medication you take
• Your age and overall health
• Whether you take multiple medications or supplements
• Whether you have liver, kidney, heart, bleeding, immune or mental health conditions

This is especially important for people taking medications with a narrow therapeutic index. These are medicines where even a small change in drug levels can make a difference in safety or effectiveness. Examples can include warfarin, digoxin, cyclosporine and certain seizure medications.

Why “natural” does not always mean safe

Herbal teas are often marketed as gentle, calming or wellness-supporting. Many people use them for sleep, digestion, stress, nausea, immune support or mood. But “natural” products can still have powerful effects in the body.

The same is true for many herbal supplements. A tea may contain a lower amount of an herb than a capsule or extract, but the risk is not always zero. Some teas include concentrated blends, multiple herbs or ingredients that are not obvious from the front of the package.

That is why it is important to read labels carefully. A tea marketed for “calm,” “sleep,” “detox,” “focus,” “immunity” or “mood support” may contain herbs that can interact with medications.

Herbal teas that may interact with medications

The herbal teas below are common examples of teas that may affect certain medications. This list is not complete, and not every interaction applies to every person. Before using herbal teas regularly for wellness purposes, ask your doctor or pharmacist whether the ingredients are safe with your medications.

St. John’s wort tea

Why people drink it: St. John’s wort is often promoted for mood support.

Medication concern: St. John’s wort is one of the best-known herbs for drug interactions. It may reduce the effectiveness of several medications by speeding up the way the body breaks them down. It may also increase the risk of serotonin-related side effects when combined with certain antidepressants or other medications that affect serotonin.

St. John’s wort may interact with medications such as:

• Antidepressants
• Birth control pills
• Blood thinners
• Some heart medications
• Some HIV medications
• Some transplant medications
• Certain pain medications
• Some cancer medications

People taking antidepressants should be especially cautious. Combining St. John’s wort with medications that affect serotonin may increase the risk of serotonin toxicity, sometimes called serotonin syndrome.

Serotonin is a chemical messenger that helps regulate mood, behavior, digestion, appetite, memory and body temperature. When serotonin levels become too high, symptoms can range from mild to severe. Warning signs may include tremor, agitation, sweating, diarrhea, confusion, muscle stiffness, fever or a rapid heartbeat.

Seek medical care right away if you develop severe symptoms or believe you may be experiencing serotonin toxicity.

Ginkgo biloba tea

Why people drink it: Ginkgo biloba is often promoted for memory, focus or cognitive support.

Medication concern: Ginkgo may increase bleeding risk, especially for people taking anticoagulant or antiplatelet medications.

Use caution with ginkgo if you take medications such as:

• Warfarin
• Aspirin
• Clopidogrel
• Nonsteroidal anti-inflammatory drugs, such as ibuprofen or naproxen
• Other medications that affect bleeding or clotting

People scheduled for surgery or procedures should also tell their care team if they use ginkgo or any herbal products. Your clinician may recommend stopping certain herbal products before a procedure to reduce bleeding or anesthesia-related risks.

Chamomile tea

Why people drink it: Chamomile is commonly used for relaxation, sleep, anxiety, indigestion or general calming.

Medication concern: Chamomile may interact with blood thinners and certain medications that affect the immune system. People taking warfarin, cyclosporine or other medications with important dosing requirements should ask a clinician before drinking chamomile regularly.

Chamomile may also be a concern for people with allergies to plants in the daisy family, including ragweed, chrysanthemums, marigolds and daisies.

Ginger tea

Why people drink it: Ginger tea is often used for nausea, digestion or soothing an upset stomach.

Medication concern: Ginger may increase bleeding risk in some people, especially when used regularly or in large amounts with blood-thinning medications. It may also affect blood sugar or blood pressure in some cases.

Use caution with ginger tea if you take:

• Blood thinners
• Aspirin or other antiplatelet medications
• Diabetes medications
• Blood pressure medications

Small amounts of ginger used in food may not carry the same level of concern as concentrated supplements or large, frequent servings of strong ginger tea. Still, people on medications should ask a doctor or pharmacist what amount is appropriate.

Valerian root tea

Why people drink it: Valerian root is commonly promoted for sleep or relaxation.

Medication concern: Valerian may increase drowsiness, especially when combined with other substances or medications that slow the central nervous system.

Use caution with valerian root tea if you take:

• Prescription sleep medications
• Benzodiazepines or other anxiety medications
• Opioid pain medications
• Muscle relaxers
• Sedating antihistamines
• Alcohol or other sedating substances

Combining valerian with sedating medications may increase the risk of extreme sleepiness, slowed reflexes, dizziness, confusion or falls. Do not drive or operate machinery if you feel drowsy after using valerian.

Kava tea

Why people drink it: Kava is traditionally used for stress relief, relaxation or anxiety.

Medication concern: Kava may interact with sedatives, antidepressants, anticonvulsants and other medications. It has also been associated with liver injury in some cases.

Use caution with kava if you take:

• Sedatives or sleep medications
• Anti-anxiety medications
• Antidepressants
• Seizure medications
• Medications that affect the liver
• Alcohol

People with liver disease or people taking medications that may affect the liver should avoid kava unless a clinician specifically says it is safe. Warning signs of liver problems can include unusual fatigue, nausea, loss of appetite, dark urine, pale stools, abdominal pain or yellowing of the skin or eyes. Seek medical care promptly if these symptoms occur.

Ashwagandha tea

Why people drink it: Ashwagandha is often promoted for stress, sleep, energy or general wellness.

Medication concern: Ashwagandha may interact with several types of medications and may not be appropriate for everyone. It may affect thyroid function, blood sugar, blood pressure, the immune system or sedative effects.

Use caution with ashwagandha if you take:

• Thyroid medication
• Diabetes medication
• Blood pressure medication
• Sedatives
• Immunosuppressants
• Medications for autoimmune conditions

People who are pregnant, breastfeeding, have autoimmune disease, have thyroid conditions or take multiple medications should talk with a clinician before using ashwagandha.

Goldenseal tea

Why people drink it: Goldenseal is often promoted for colds, digestion or immune support.

Medication concern: Goldenseal may affect how the body processes certain medications. Because it may interfere with drug metabolism, it can potentially change medication levels in the body.

Use caution with goldenseal if you take prescription medications, especially medications with narrow dosing ranges or medicines that require consistent blood levels. Ask your doctor or pharmacist before using goldenseal tea or supplements.

Other herbs and teas to ask your doctor or pharmacist about

Some other herbs and tea ingredients may also interact with medications or affect medical conditions. These include:

• Echinacea
• Garlic
• Milk thistle
• Green tea extract or high-caffeine green tea products
• Licorice root
• Turmeric
• Cranberry
• Black cohosh
• Dong quai
• Ginseng

This does not mean everyone needs to avoid these herbs. It simply means people who take medications should check before using them regularly, especially in concentrated teas, powders, extracts or supplements.

Which medications are more likely to interact with herbal teas?

Herbal teas and supplements may be more concerning for people taking certain medication categories. These include:

• Blood thinners and antiplatelet medications
• Antidepressants and other serotonin-affecting medications
• Anti-anxiety medications and sedatives
• Sleep medications
• Seizure medications
• Heart rhythm medications
• Blood pressure medications
• Diabetes medications
• Birth control pills
• HIV medications
• Transplant medications
• Immunosuppressants
• Pain medications
• Cancer treatments
• Medications processed by the liver
• Medications with a narrow therapeutic index

If you take any of these, ask your doctor or pharmacist before adding herbal teas for a specific health benefit.

Signs an herbal tea may be affecting your medication

Call your doctor, pharmacist or another healthcare professional if you notice new or unusual symptoms after starting a new herbal tea, supplement or wellness product.

• Possible warning signs include:
• Unusual bruising or bleeding
• Nosebleeds or bleeding gums
• Black or bloody stools
• Severe headache or dizziness
• Extreme drowsiness
• Confusion
• Agitation or restlessness
• Tremor or shaking
• Rapid heartbeat
• Sweating or fever
• Nausea, vomiting or diarrhea
• Yellowing of the skin or eyes
• Dark urine
• Mood changes
• Low blood sugar symptoms, such as shakiness, sweating or weakness
• Very low blood pressure symptoms, such as fainting or lightheadedness

Call 911 or seek emergency care if symptoms are severe, sudden or life-threatening.

How to enjoy herbal tea more safely

You may not need to give up herbal tea. But if you take medications, it is smart to sip with more awareness. Before adding a new herbal tea, consider these steps:

• Ask your doctor or pharmacist whether the ingredients are safe with your medications.
• Bring the tea box, ingredient list or a photo of the label to your appointment or pharmacy.
• Read the full ingredient list, not just the front of the package.
• Be careful with teas marketed for sleep, detox, mood, stress, focus, immunity or weight loss.
• Avoid using herbal teas as a substitute for prescribed medication.
• Use herbal teas in moderation unless your clinician recommends otherwise.
• Tell every member of your care team about teas, supplements and natural products you use.
• Stop using the product and seek guidance if you notice unusual symptoms.

It is also important to tell your care team about herbal products before surgery, dental procedures or new prescriptions. This helps your clinicians look for possible interactions before they become a problem.

What to ask your doctor or pharmacist

If you are unsure whether an herbal tea is safe for you, ask your doctor:

• Can this tea interact with any of my medications?
• Could it increase bleeding, drowsiness, blood pressure changes or blood sugar changes?
• Could it make my medication less effective?
• Is it safe with my medical conditions?
• How often is it safe for me to drink this tea?
• Should I avoid it before surgery or medical procedures?
• Are there safer alternatives for sleep, stress, nausea or digestion?

Your pharmacist can also be especially helpful because pharmacists are trained to evaluate medication interactions, including interactions with supplements and herbal products.

The bottom line on herbal teas and medication safety

Herbal tea can be a comforting ritual, and many people enjoy it without problems. But some herbal teas can affect medications, especially when used regularly or combined with prescriptions for chronic conditions.

The safest approach is simple: do not assume a tea is safe just because it is natural. Read the label, know what is in your cup and ask your doctor or pharmacist before adding herbal teas to your daily routine.

Frequently asked questions

Can herbal tea interact with prescription medication?

Yes. Some herbal teas can interact with prescription medications by increasing side effects, reducing effectiveness or changing how the body processes a drug. The risk depends on the herb, the medication, how often you drink the tea and your personal health history.

What herbal teas should I avoid with blood thinners?

People taking blood thinners or antiplatelet medications should ask a doctor or pharmacist before drinking teas that contain ginkgo biloba, ginger, chamomile, garlic, turmeric, dong quai or other herbs that may affect bleeding or clotting. Do not stop or change a prescribed blood thinner without medical guidance.

Can St. John’s wort tea affect antidepressants?

Yes. St. John’s wort may interact with antidepressants and other medications that affect serotonin. Combining them may increase the risk of serotonin-related side effects, which can sometimes be serious. It may also reduce the effectiveness of several medications, including birth control pills and some heart, HIV, transplant and pain medications.

Is chamomile tea safe with medication?

Chamomile tea is common, but it may not be safe for everyone. It may interact with blood thinners, transplant medications or other drugs with important dosing requirements. People with allergies to ragweed, daisies, marigolds or related plants should also use caution.

Can ginger tea interact with medication?

Ginger tea may interact with blood thinners, diabetes medications and blood pressure medications, especially when used often or in large amounts. Ask your doctor or pharmacist what amount of ginger is safe for you.

Can valerian root tea be taken with sleep medicine?

Valerian root may increase drowsiness when combined with prescription sleep medications, anti-anxiety medications, opioids, muscle relaxers, sedating antihistamines or alcohol. Combining sedating products can increase the risk of dizziness, slowed reflexes, falls or extreme sleepiness.

Is kava tea safe?

Kava may not be safe for everyone. It can interact with sedatives, antidepressants, seizure medications and other drugs. Kava has also been associated with liver injury. People with liver disease or people who take medications that affect the liver should avoid kava unless their clinician says it is safe.

Should I tell my doctor about herbal teas?

Yes. Tell your doctor and pharmacist about all herbal teas, supplements, vitamins and natural products you use, especially if you drink them regularly or use them for a health purpose. This helps your care team check for possible interactions with your medications or medical conditions.

Is one cup of herbal tea always safe?

Not always. One cup may be low risk for many people, but safety depends on the herb, the strength of the tea, your medications and your health conditions. Some people should avoid certain herbs entirely. When in doubt, ask a healthcare professional.

Who should be most careful with herbal teas?

People who should be especially cautious include those who take multiple medications, blood thinners, antidepressants, sedatives, diabetes medications, blood pressure medications, transplant medications, immune-suppressing medications or seizure medications. People who are pregnant, breastfeeding, preparing for surgery or living with liver, kidney, heart, bleeding, immune or mental health conditions should also check with a clinician.

References

1. National Center for Complementary and Integrative Health. How Medications and Supplements Can Interact.
2. National Center for Complementary and Integrative Health. Herb-Drug Interactions.
3. U.S. Food and Drug Administration. Mixing Medications and Dietary Supplements Can Endanger Your Health.
4. National Center for Complementary and Integrative Health. St. John’s Wort
5. National Center for Complementary and Integrative Health. Ginkgo
6. National Institutes of Health Office of Dietary Supplements. Valerian: Health Professional Fact Sheet.
7. National Center for Complementary and Integrative Health. Kava
8. MedlinePlus. Herbs and Supplements.