7 Medications That Don’t Mix Well with Herbal Tea

Herbal teas have been used for centuries across the globe for their medicinal or immune-supporting properties. Since they’re made from plants, it’s easy to assume they’re harmless. But there’s a dangerous downside we don’t hear about very often. “A lot of people don’t think about herbal teas as something that they need to worry about interacting with medication,” says Ginger Hultin, D.C.N., RDN, CSO. “But, many vitamins, minerals and herbal products have moderate to sometimes severe interactions with medications.” Because many herbal teas have similar properties to medications, their side effects can compound, she adds. 

That’s not the only way mixing herbal teas with medication may spell trouble, says Melissa Groves Azzaro, RDN, LD. “Some herbal teas can interact with medications because they are metabolized by the same pathways in the liver. As a result, herbal teas can increase the effects of your medication or make it less effective.” And these seemingly healthy teas can interact with over-the-counter and prescription medications. So, if you’re drinking them and taking OTC meds, your pharmacist may not even be aware that you’re at risk for these interactions. 

Which medications should you avoid if you drink herbal tea? To find out, we asked health experts. Here’s what they told us.

1. Antidepressants

Some herbal remedies are used to improve mood and depression, especially St. John’s wort. However, if you’re taking antidepressants, you’ll want to avoid any teas containing St. John’s wort. Research has found that combining this herb with antidepressants called selective serotonin reuptake inhibitors (SSRIs) may cause a condition called serotonin syndrome. On the mild end, this can lead to nausea, vomiting and diarrhea. At the extreme, it may cause more severe symptoms, like rapid heartbeat, high blood pressure, uncontrollable muscle movements, agitation and hallucinations. , 

Antidepressants aren’t the only medications that don’t mix well with St. John’s wort, says Hultin. “St. John’s wort is an herbal supplement that has a lot of interactions with medications,” she explains. “Because of the large list of medications that interact with St. John’s wort, you need to use a lot of caution before incorporating it into your diet via tea or supplements and be sure you’re checking with your medical team about it for your safety.”

2. Omeprazole

If you’re one of the millions of Americans with frequent heartburn or GERD (aka gastroesophageal reflux disease), omeprazole may be a staple in your medicine cabinet. This medication, also sold under the name brand Prilosec, may not work nearly as well when you combine it with certain herbal teas, especially ginkgo biloba. That’s because this popular herb may interfere with omeprazole’s metabolism. The result? Your medication becomes less effective, and your heartburn doesn’t budge. 

3. Blood Thinners & Ibuprofen

“When taking blood-thinning medication, you need to use caution with certain teas,” says Hultin. That doesn’t just include prescription blood thinners, like warfarin. It also applies to ibuprofen.

According to the National Institutes of Health, ginkgo biloba, cat’s claw and chamomile may all increase the risk of bleeding in people taking blood thinners, like warfarin. , ,  Research has also found that ginseng may increase bleeding risk.  

There have even been reports of fatal cerebral hemorrhage among healthy men who combined ginkgo with ibuprofen. “This is a class of medication that you need to be careful with regarding teas and other supplements you might be taking, even seemingly ‘safe’ options,” says Hultin.

4. Metformin

Metformin is one of the most commonly prescribed blood sugar-lowering medications for people with type 2 diabetes. If you’re taking it, make sure to steer clear of goldenseal tea, says Azzaro. Research has shown that goldenseal (also known as yellow root or golden root) may decrease metformin levels in the blood by as much as 25%. That could make your metformin considerably less effective.

On the opposite end of the spectrum, ginseng has been shown to lower blood sugar. So, drinking ginseng tea with metformin could lead to hypoglycemia, which can also have dangerous consequences.

5. Statins

Grapefruit tea is refreshing and delicious. However, grapefruit can interact with a long list of medications, especially cholesterol-lowering drugs called statins. For instance, research has found that grapefruit can raise blood levels of atorvastatin. This may lead to liver damage and possibly even a serious condition called rhabdomyolysis that accelerates muscle breakdown. 

That’s not all. Mixing atorvastatin with St. John’s wort–containing herbal teas may have the opposite effect, decreasing atorvastatin’s effectiveness and blunting its cholesterol-lowering action.  

6. Cyclosporine

Cyclosporine is a medication used after an organ transplant to prevent organ rejection. It is also used to treat certain autoimmune diseases, such as rheumatoid arthritis and psoriasis. If you’re taking cyclosporine, definitely talk to your health care provider before drinking any kind of herbal tea, as this medication has dangerous interactions with several drugs, says Hultin. For instance, grapefruit, chamomile and berberine may increase cyclosporine levels in the blood. Conversely,  St. John’s wort may block cyclosporine’s effectiveness.

7. Benzodiazepines

Some people sip valerian tea to alleviate stress, anxiety or depression. But combining it with anti-anxiety medications, like benzodiazepines such as diazepam (Valium), alprazolam (Xanax) or clonazepam (Klonopin) can be dangerously sedating. So, choose one or the other, but not both. 

Potential Risks of Herbal Tea and Medication Interactions

“Herbal teas may lower blood pressure or blood sugar, and many people are on medications that also have those mechanisms,” says Hultin. “It’s important to run any herbal product or tea by your pharmacist, doctor or dietitian to check for safety first.” 

Once you do, you may find that you can still enjoy these teas—with a few caveats. “If an herbal tea has a moderate interaction, it doesn’t mean do not use, it just means use with caution,” says Azzaro. “This means if someone on diabetes medications regularly uses a tea that may lower blood sugar, we don’t necessarily have them stop using the tea. We have them monitor their blood sugar and adjust the dose of medications as needed,” she says

Once you get the green light from your health care provider, Azzaro recommends only purchasing herbal teas from trusted sources. While the online dealer selling them at a discount may seem attractive, there’s no guarantee exactly what is in their tea.

Our Expert Take

Herbal teas may offer a refreshing way to relax and unwind. But they aren’t a one-sip-fits-all kind of beverage. Many herbal teas can have dangerous interactions with lots of medications, especially antidepressants, omeprazole, blood thinners, metformin, statins, cyclosporine and benzodiazepines. These drugs may not safely mix with herbal teas containing St. John’s wort, ginkgo biloba, grapefruit, valerian, ginseng and others. “Although herbal teas are natural, that doesn’t mean they’re safe or appropriate for everyone,” says Azzaro. “Many herbs contain bioactive substances that can interact with medications, so it’s always best to check with your doctor whether a specific herbal tea is right for you or not.”