The short answer
Yes, some Chinese herbs interact with prescription medicines — and a few of those interactions are serious. This is not a reason to avoid TCM. It is a reason to tell both of your prescribers everything you are taking, and never to stop a prescription in order to take a herb.
The most important sentence on this page: if you take a blood thinner, an immunosuppressant, a cancer drug, digoxin, or a medicine for HIV or epilepsy, do not start a herbal formula without checking with the doctor who prescribes that medicine. These are the drug classes with the narrowest margin for error.
This page is general information, not medical advice, and it cannot account for your particular medicines and condition. Talk to a qualified clinician about your own combination.
The documented interactions
The table below reflects interactions set out by the US National Center for Complementary and Integrative Health and the standard pharmacology literature. It is not exhaustive — hundreds of herbs are in use — but these are the ones with a documented basis.
| Herb | Interacts with | What happens |
|---|---|---|
| Ginkgo biloba | Warfarin; efavirenz | With warfarin, associated with an increased risk of major bleeding compared with warfarin alone. Combined use with efavirenz is not recommended. |
| St John's wort | Cyclosporine, indinavir, oral contraceptives, warfarin, digoxin, benzodiazepines | A potent inducer of cytochrome P450 enzymes and intestinal P-glycoprotein — it speeds up clearance of other drugs, reducing their effect. One of the best-documented herb-drug interactions there is. |
| Asian ginseng | Calcium channel blockers, other antihypertensives, statins, some antidepressants | Interaction potential is uncertain rather than established. Studies on warfarin have had mixed results. Worth flagging to your doctor rather than assuming it is inert. |
| Chamomile | Oral contraceptives; warfarin; sedatives (theoretical) | May reduce the effectiveness of oral contraceptives. Interactions reported with warfarin and with other liver-metabolised drugs. |
| Goldenseal | Metformin | Reduces metformin blood levels by roughly 25%, which can undermine glucose control in type 2 diabetes. |
| Green tea (high doses) | Nadolol; atorvastatin | Reduces blood levels — and therefore the effectiveness — of the beta-blocker nadolol and of atorvastatin. |
| Cat's claw | Anticoagulants/antiplatelets, antihypertensives, calcium channel blockers, CYP3A4 substrates, immunosuppressants | A broad interaction profile; treat with particular caution alongside blood thinners and transplant medication. |
| Cranberry | Warfarin | Evidence is conflicting — some reports suggest an interaction, others do not. Flag it rather than assume either way. |
An important caveat about this table. NCCIH notes that most identified herb-drug interactions are hypothetical, inferred from animal studies or cell assays rather than confirmed in patients. That cuts both ways: it means the list above is probably incomplete, and it means an entry on it is not proof of harm in every person. What it is proof of is that the combination deserves a conversation, not silence.
What the evidence actually supports in TCM
Being clear-eyed about interactions is not the same as dismissing TCM. Some parts of it have a solid evidence base and are used inside mainstream Chinese hospitals, and others do not.
Reasonably well supported
- Acupuncture for chronic pain — back pain, osteoarthritis and migraine. Systematic reviews generally find meaningful reductions in pain compared with sham controls.
- Acupuncture for chemotherapy-induced nausea — well supported, and offered alongside chemotherapy as standard practice in many Chinese oncology departments.
- Specific herbal compounds. Artemisinin, derived from sweet wormwood, won the 2015 Nobel Prize in Physiology or Medicine for malaria treatment — a reminder that a traditional herb can become a mainstream drug.
Treat with scepticism
- Claims that a herbal formula alone cures cancer, reverses chronic disease, or "detoxifies" the body.
- Any practitioner who tells you to stop conventional treatment — particularly chemotherapy, immunosuppressants or cardiac medication.
- Products sold for a named disease with dramatic testimonials and no ingredient transparency.
TCM works best as a complement — symptom management, recovery support, quality of life — not as a replacement for surgery, chemotherapy or other treatments with proven effect.
Six rules if you are using both
- Tell both prescribers everything. Your Chinese doctor and your doctor at home each need the complete list — prescriptions, herbs, supplements, everything, including doses.
- Never stop a prescription to take a herb. If a practitioner suggests it, get a second opinion from the clinician who prescribed it.
- Write down the exact formula. Chinese herbal formulas are often multi-herb. Ask for the ingredient list in writing, with the Latin names, so your home doctor can check it.
- Do not rely on spacing doses apart. Separating doses by a few hours does not fix a real interaction — enzyme induction and blood-level effects do not work that way.
- Be most careful with narrow-margin drugs — cancer chemotherapy, warfarin and other anticoagulants, digoxin, immunosuppressants, antiepileptics and antiretrovirals.
- Buy from a hospital pharmacy, not a marketplace listing. Unregulated herbal products carry risks of mislabelling, contamination and undisclosed pharmaceutical ingredients, quite apart from the herb itself.
Finding a practitioner worth seeing
In China, look for a practitioner licensed by the National Medical Products Administration (NMPA) practising within a university-affiliated TCM hospital. These institutions have standardised, quality-controlled herbal pharmacies and international departments with English-speaking staff, and they operate within a regulated system.
Be cautious of standalone clinics promising miracle cures, and of anyone who discourages you from telling your other doctors what you are taking. A confident practitioner has no problem with you verifying the formula.
Where you source herbs matters as much as which herb. Ask the hospital's international department which pharmacy dispenses their formulas and whether a written ingredient list is available.
Frequently Asked Questions
Can I take Chinese herbal medicine with my prescription medication?
Sometimes, but not without checking. Ginkgo biloba with warfarin is associated with a higher risk of major bleeding than warfarin alone, and St John's wort speeds the clearance of cyclosporine, oral contraceptives, warfarin, digoxin and several other drugs. Tell both prescribers exactly what you are taking, and never stop a prescription in order to take a herb.
Is it safe to mix TCM and Western medicine?
They are routinely combined in Chinese hospitals, sometimes deliberately and under supervision. The risk is untracked self-medication. Both practitioners need the full list. Only some interactions are well documented, and extra care is needed with narrow therapeutic index drugs such as chemotherapy agents, warfarin and digoxin.
Do Chinese herbs interact with blood thinners?
Several do, and this is the class to take most seriously. Ginkgo with warfarin increases major bleeding risk; chamomile has been linked with warfarin interactions; cat's claw may interact with anticoagulants and antiplatelets; cranberry evidence is conflicting. If you take warfarin, a DOAC, aspirin or clopidogrel, do not start a formula without telling your prescriber.
Are Chinese herbs safe to buy online?
Unregulated herbal products carry risks unrelated to the herbs themselves — mislabelling, substitution, heavy metal or pesticide contamination, and undisclosed pharmaceutical ingredients. A hospital pharmacy attached to a university-affiliated TCM hospital dispenses standardised, quality-controlled preparations and is a safer source.
Want a hospital that takes this seriously?
We work with hospitals that run integrated Chinese and Western medicine properly — where the TCM department and the oncology or cardiology team sit in the same building and talk to each other, and where you get the formula in writing.
Ask About Integrated Care →Related
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Sources: US National Center for Complementary and Integrative Health, Herb-Drug Interactions (provider digest); standard herb-drug interaction literature. This page is general information only. It is not medical advice and does not replace a consultation with a qualified clinician who knows your history and medicines.