Yes. Medicinal herbs can change how prescription drugs work, sometimes enough to make a medicine less effective or increase side effects. The best-established examples involve herbs that alter drug metabolism, affect blood clotting, change sedation, or act on the same body systems as a prescription medicine. Current U.S. guidance from the National Center for Complementary and Integrative Health (NCCIH) and the Food and Drug Administration (FDA) continues to emphasize the same practical point: tell your clinician or pharmacist about every herbal product you use before you start, stop, or change a prescription drug.
This article does not diagnose any individual reaction. A new symptom after combining a herb and a medicine may be caused by an interaction, by the medicine itself, by the underlying condition, by a different product, or by something unrelated. The safest response is to look at timing, dose, product ingredients, and the specific prescription involved rather than assuming the herb is either harmless or definitely responsible.
Herbs and prescription drugs can interact through several mechanisms. An herb may speed up the enzymes or transporters that clear a medicine from the body, lowering the drug level. Another herb may slow drug clearance, raising the level. Some herbs also add to a medicine’s pharmacologic effect, such as increasing sedation or affecting bleeding risk. FDA consumer guidance explains that supplements can alter the absorption, metabolism, or excretion of medicines, which can make a drug too weak or too strong. See FDA guidance on mixing medicines and dietary supplements.
What to do: If you take a prescription medicine and are considering a new herb, check the exact product with a pharmacist or prescribing clinician first. Bring the bottle or a photo of the ingredient panel, because “herbal blend” names are often too vague to assess reliably.
Among commonly used medicinal herbs, St. John’s wort has some of the strongest evidence for clinically important drug interactions. NCCIH states that it can speed up processes that convert many medicines into inactive substances, lowering drug levels. It can weaken the effects of medicines including cyclosporine, some seizure medicines, warfarin, some HIV medicines, some cancer medicines, certain statins, some heart medicines, and hormonal birth control. It can also interact with medicines that affect serotonin, including some antidepressants, in a way that may increase serious serotonin-related effects. Current NCCIH information is available at St. John’s Wort: Usefulness and Safety.
This is not a reason to assume that everyone taking St. John’s wort will have a dangerous reaction. Risk depends on the prescription drug, dose, herbal preparation, timing, and individual factors. But it is a strong reason not to add or discontinue St. John’s wort without checking first when an important prescription medicine is involved.
What to do: If you already take St. John’s wort with a prescription drug, do not automatically stop either product based only on an internet interaction list. Contact a pharmacist or the prescriber promptly so they can tell you whether the combination matters for your specific medication and whether monitoring or a supervised change is needed.
NCCIH’s current herb–medicine interaction guidance distinguishes stronger evidence from uncertainty. That distinction matters because many online lists present every theoretical interaction as if it were proven in people.
| Herb or product | What current guidance says | Practical implication |
|---|---|---|
| St. John’s wort | High potential for clinically important interactions with many medicines; can lower drug levels and may increase serotonin-related effects with certain drugs. | Check before starting or stopping it if you take any prescription medicine. |
| Goldenseal | May change how the body processes many drugs; NCCIH specifically notes a potential interaction with metformin. | Ask a pharmacist to check the exact prescription and product. |
| Concentrated green tea extract | Can reduce blood levels of some drugs, including atorvastatin and nadolol, according to NCCIH. | Do not assume a concentrated extract behaves like an ordinary cup of tea. |
| Asian ginseng | Possible interactions have been reported or proposed with blood-pressure medicines, statins, and some antidepressants, but uncertainties remain. | Treat the interaction as something to verify, not as proof that a symptom was caused by ginseng. |
The NCCIH summary is available at 6 Tips: How Herbs Can Interact With Medicines.
因應方法：當證據不確定時，避免兩個截然相反的錯誤：不要排除藥物交互作用的可能性，也不要假定藥物交互作用一定能解釋所有症狀。請查閱處方標籤、草藥成分錶以及專業的藥物交互作用資源。
草藥產品含有生物活性化學物質。這既是人們使用它們的原因之一，也是它們可能與藥物產生交互作用的原因。在美國，膳食補充劑的監管方式與處方藥不同，通常無需獲得美國食品藥物管理局 (FDA) 的批准即可銷售。 FDA 還警告說，膳食補充劑可能含有具有強烈生物活性的成分，並且某些產品存在品質或標籤問題。請參閱FDA 101：膳食補充劑。
不同產品之間的差異至關重要。即使兩瓶產品標籤上都標示是同一種草藥，它們所使用的植物部位、萃取方法、濃度或添加成分也可能不同。茶、酊劑、標準化萃取物和複方草藥膠囊並非一定可以互換使用。
操作步驟：記錄品牌、完整產品名稱、服用劑量、服用量、使用頻率。如果可能，請保留包裝，直到問題解決。
美國國家補充與綜合健康中心（NCCIH）特別建議，當草本產品與治療指數較窄的藥物合用時，應格外謹慎。這類藥物的濃度即使發生微小的變化，也可能導致治療效果從無效變為有害。 NCCIH列舉的例子包括地高辛、環孢素和華法林。
其他高風險情況可能包括用於預防癲癇發作、預防器官移植排斥反應、治療愛滋病或癌症、控制心律不整或預防嚴重血栓事件的藥物。具體風險取決於藥物種類。籠統地說「草藥會幹擾血液稀釋劑」或「草藥會幹擾心臟藥物」過於模糊，不足以引導安全決策。
應該怎麼做：如果某種藥物需要定期驗血、監測藥物濃度或仔細調整劑量，那麼在服用第一劑之前，最好先檢查一下新的草藥產品。
並非所有新出現的症狀都意味著存在危險的草藥-藥物交互作用。常見的可能原因包括：藥物的預期副作用、草藥的預期副作用、空腹服用、不同補充劑含有重複成分、脫水、飲酒、近期劑量調整，或原有病情自行改善。此外，症狀也可能與藥物交互作用無關。
時間點很重要。詢問症狀是否是在開始服用草藥、改變劑量、更換品牌、開始服用處方藥或改變處方藥劑量後出現的。清晰的時間軸並不能證明因果關係，但可以為臨床醫生提供有用的信息。
操作方法：記錄每種產品的開始使用時間、劑量調整時間、症狀出現時間。包括漏服的劑量以及同期服用的任何非處方藥。
某些藥物交互作用會降低血液中處方藥的濃度。聖約翰草就是一個典型的例子，因為它能增強藥物代謝途徑和轉運蛋白的活性。這可能導致藥物暴露量減少，從而降低療效。
但藥物「藥效減弱」可能還有其他原因：漏服、嘔吐或腹瀉、所治療的疾病發生變化、服用了新的相互作用的處方藥，或者儲存不當。未經專業指導，切勿以加倍劑量來彌補藥效減弱。
因應方法：如果在添加草藥產品後，某種藥物似乎停止起作用，請聯繫處方醫生或藥劑師，而不是自行增加處方劑量。
藥物交互作用也可能疊加。例如，鎮靜草藥與鎮靜處方藥合用可能會加劇嗜睡。影響凝血的產品可能會增強抗凝血劑或抗血小板藥物的作用。具有血清素活性的草藥可能會增強提高血清素水平的藥物的作用。
具體風險取決於草藥種類和處方。網路上發布的警告往往過於籠統，無法確定對特定個體而言的實際風險。
應對措施：在核對密碼組合之前，如果您突然感到困倦、頭暈或意識不清，請避免駕駛或從事其他危險活動。如果症狀嚴重或迅速惡化，請立即就醫。
有些症狀不應等到常規藥物交互作用檢查才被發現。美國食品藥物管理局 (FDA) 列出了飲食補充劑可能引起的嚴重反應，包括咽喉、嘴唇或舌頭腫脹；喘息或呼吸急促；昏厥；胸痛；心悸或心律不齊；嚴重持續性嘔吐或腹瀉；嘔吐物、糞便、尿液或痰液中帶血；異常出血；皮膚或眼睛發黃；嚴重行為改變；以及類似中風的症狀。請參閱FDA 關於嚴重補充劑反應的指南。
聖約翰草與血清素能藥物併用也可能引發嚴重的血清素相關不良反應。 MedlinePlus建議，如果出現血清素症候群的症狀，應立即聯繫臨床醫師；嚴重症狀可能危及生命。請參閱MedlinePlus上關於血清素症候群的資訊。
應對措施：如果出現呼吸困難、臉部或喉嚨嚴重腫脹、昏厥、類似中風的症狀、嚴重的胸部症狀或其他迅速惡化的反應，請立即撥打 911 或當地急救電話。不要等到完成線上互動搜尋後再採取行動。
發現草藥與藥物之間可能存在交互作用固然令人擔憂，但突然停用處方藥可能會帶來第二種風險。某些藥物如果突然停用，可能會引起戒斷症狀、反彈效應、癲癇發作風險、血壓變化、血栓風險，甚至導致病情惡化。
最安全的做法通常是先確定藥物種類，評估情況的緊急程度，然後詢問處方醫生或藥劑師是否需要先更換某種藥物。如果出現嚴重不良反應，急診醫師可能會建議採取與常規處理不同的緊急措施。
應該怎麼做：除非臨床醫生有緊急指示，否則不要僅僅因為在網路上發現可能存在藥物交互作用就自行停止服用重要的處方藥。
美國食品藥物管理局 (FDA) 建議，所有處方藥、非處方藥、膳食補充劑、維生素、植物藥、礦物質和草藥都應與臨床醫生或藥劑師討論。處方標籤和患者用藥指南也可能包含具體的藥物交互作用警告。您可以透過美國國家醫學圖書館的DailyMed資料庫查詢藥品標籤資訊。
草藥可能會改變處方藥的療效，但並非所有草藥或藥物的風險都相同。聖約翰草就是一個典型的例子，它與多種藥物有重要的臨床交互作用。北美黃連和濃縮綠茶萃取物也存在已知的相互作用問題，而其他一些草藥的相關證據尚不完整或取決於具體情況。
下一步最有效的辦法不是自行診斷藥物交互作用。列出你正在服用的所有藥物，記錄下哪些藥物發生了變化以及變化的時間，然後請藥劑師或處方醫生仔細核對藥物組合。如果出現嚴重過敏反應、大出血、昏厥、胸部症狀、類似中風的症狀或其他迅速惡化的症狀，請立即尋求緊急醫療協助，而不是等待例行藥物評估。
Medicinal herbs can raise or lower prescription drug effects. Learn which interactions are well established, what remains uncertain, and which warning signs need urgent care.
Nguyen Tran Anh Thu 醫生分享肉荳蔻。肉荳蔻還用於治療腹瀉、嘔吐、消化系統疾病，有時還用於增強厭食症的風味。
雄木瓜花用於治療呼吸道疾病，如咳嗽、喉炎……據說有抗乳腺癌的作用。
