Herbal Teas and Medications: Potential Interactions You Need to Know

Many people drink herbal teas thinking they’re harmless-just a warm, natural sip of comfort. But if you’re taking prescription medications, that cup of chamomile, hibiscus, or green tea could be doing more than soothing you. It might be changing how your drugs work-sometimes dangerously.

Why Herbal Teas Aren’t Just ‘Herbal’

Herbal teas aren’t tea in the traditional sense. They don’t come from the Camellia sinensis plant. Instead, they’re made from roots, flowers, leaves, or seeds of other plants-chamomile, peppermint, echinacea, hibiscus, St. John’s wort, and more. People drink them for sleep, digestion, immunity, or just because they taste good. But unlike pharmaceuticals, these teas aren’t tested for safety before they hit store shelves. The FDA treats them as food, not medicine. That means no proof of effectiveness, no required warning labels, and no standard dosing.

That’s a problem when you’re on medications that need to stay in a very narrow range to work. Drugs like warfarin, digoxin, cyclosporine, and theophylline have tiny windows between helping you and harming you. Even small changes in how your body absorbs or breaks them down can lead to serious side effects.

Green Tea: The Silent Drug Thief

Green tea is one of the most common herbal teas-and one of the most dangerous when mixed with certain drugs. It’s not just about caffeine. The real issue is epigallocatechin gallate (EGCG), a powerful antioxidant that interferes with how your body moves drugs around.

A 2023 study showed that drinking three cups of strong green tea daily cut the blood levels of nadolol, a beta-blocker used for high blood pressure and heart rhythm issues, by 85%. That’s not a small drop. It means the drug isn’t working. Your heart rate might spike, your blood pressure could climb, and you might not even realize why.

Green tea also messes with statins. Atorvastatin, a cholesterol-lowering drug, saw its effectiveness drop by 31-39% in people who drank green tea regularly. That’s a big deal if you’re trying to avoid a heart attack or stroke. The reason? Green tea blocks transporters in your gut and liver-OATP1A1 and OATP1A2-that are needed to get these drugs into your bloodstream. It’s like putting a lock on the door your medicine needs to walk through.

St. John’s Wort: The Fast-Track to Drug Failure

St. John’s wort is often used for mild depression. But if you’re on antidepressants, birth control, blood thinners, or even some cancer drugs, this tea can make them useless.

It turns on an enzyme in your liver called CYP3A4. This enzyme breaks down drugs faster than normal. So instead of staying in your system long enough to work, your medication gets flushed out too quickly. Studies show it can drop levels of cyclosporine (used after organ transplants) by up to 50%. That could lead to organ rejection. It can also make birth control fail, leading to unplanned pregnancies.

The National Center for Complementary and Integrative Health says St. John’s wort interacts with more than 50 different medications. And most people have no idea. They think, “It’s natural, so it’s safe.” But natural doesn’t mean harmless.

Chamomile, Hibiscus, and Ginkgo: The Bleeding Risks

Chamomile tea sounds gentle. But it contains apigenin, a compound that may interfere with how your body processes hormones. Early research suggests it could reduce the effectiveness of oral contraceptives by affecting liver enzymes.

Hibiscus tea is popular for lowering blood pressure. Sounds good, right? But if you’re already taking lisinopril or another ACE inhibitor, hibiscus can push your blood pressure too low. There are documented cases where patients dropped below 90 mmHg systolic-leading to dizziness, fainting, and even falls.

Ginkgo biloba tea (or supplements) is often taken for memory. But it thins the blood. When combined with warfarin, aspirin, or even ibuprofen, it can increase your risk of bleeding-sometimes severely. The American Heart Association warns people on blood thinners to avoid ginkgo, garlic, and ginseng. And yet, many still drink it thinking it’s “just a tea.”

Goldenseal and Licorice: Hidden Triggers

Goldenseal, sometimes brewed as a tea for colds, blocks two major liver enzymes: CYP2D6 and CYP3A4. That means it can either make drugs build up to toxic levels or stop them from working at all. Over 50% of prescription drugs are affected by these enzymes. That includes antidepressants, painkillers, heart meds, and even some antibiotics.

Licorice root tea is used for sore throats and digestion. But it can lower potassium levels. If you’re on diuretics (water pills) or heart medications like digoxin, that’s a recipe for dangerous heart rhythms. The FDA has flagged licorice as a risk for people with high blood pressure or heart conditions.

What You Should Do Right Now

If you’re taking any prescription medication and drink herbal teas regularly, here’s what to do:

1. Make a list. Write down every tea, supplement, or herbal remedy you take-name, how often, how much. Don’t forget the ones you only drink once a week.
2. Bring it to your doctor. Don’t wait for them to ask. Many doctors assume herbal teas are safe and won’t bring it up. But you need to tell them. A 2022 Mayo Clinic review found only 25% of older adults disclose herbal use to their providers.
3. Be specific about brewing. A weak cup of chamomile is different from a strong, steeped pot. Concentration matters. Tell your doctor how strong your tea usually is.
4. Avoid concentrated extracts. Capsules, tinctures, and powders are far more potent than brewed tea. Stick to brewed teas if you must use them, and even then, be cautious.
5. Watch for changes. If you start a new tea and notice new dizziness, fatigue, bruising, irregular heartbeat, or changes in mood or sleep, stop the tea and call your doctor.

Who’s at Highest Risk?

You’re more vulnerable if you:

• Take medications with a narrow therapeutic index (warfarin, digoxin, cyclosporine, theophylline, lithium)
• Are over 65 and on multiple medications (polypharmacy)
• Have liver or kidney disease
• Take antidepressants, blood thinners, or heart medications
• Use herbal teas daily, not just occasionally

The FDA and NCCIH both warn that older adults are the most at-risk group. They’re the ones most likely to be on multiple meds and most likely to drink herbal teas for “natural” relief. But they’re also the least likely to tell their doctors about it.

The Bigger Picture

The herbal tea market is booming. It’s expected to hit over $11 billion by 2027. Companies market blends for “immunity,” “detox,” “stress relief,” and “energy.” But there’s no oversight. No labeling requirements. No warnings about drug interactions.

Even the word “tea” tricks people. They don’t think of it as a supplement. But it’s still a bioactive substance. A cup of green tea isn’t just a drink-it’s a chemical compound interacting with your body’s systems.

Research is still catching up. Only 17% of known herb-drug interactions have been proven in human studies. That means we might be missing half the risks. Until we know more, caution is the only safe strategy.

Bottom Line

Herbal teas aren’t inherently bad. But they’re not harmless, either. If you’re on medication, treat them like you would any other drug: with respect, awareness, and open communication with your healthcare provider. Don’t assume “natural” means safe. Don’t wait for a problem to happen before you ask. Talk to your doctor. Bring your tea list. Your health depends on it.

Don’t let a warm cup of tea become a silent health risk. Your body is a complex system. What you put in it matters-especially when you’re already managing medication. Stay informed. Speak up. Your next cup of tea shouldn’t be a gamble.