Fo-ti - Lopressor HCT (Hydrochlorothiazide, Metoprolol) Interaction
Herbal: Fo-ti
Drug: Hydrochlorothiazide, Metoprolol
Brand names:
Lopressor HCT

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
May 04, 2025
Interaction Details
Hydrochlorothiazide, Metoprolol is classified as belonging to the following category: Cytochrome P450 2D6 (Cyp2D6) Substrates
Theoretically, fo-ti may increase the levels and clinical effects of drugs metabolized by CYP2D6.
Animal research suggests that fo-ti might inhibit CYP2D6. Additionally, an in vitro study suggests that the degree of CYP2D6 inhibition may depend on the type of fo-ti extract (i.e., the raw plant leads to greater inhibition than extensively processed extracts). However, this interaction has not been reported in humans.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- Zhang Y, Ding T, Diao T, Deng M, Chen S. Effects of Polygonum multiflorum on the activity of cytochrome P450 isoforms in rats. Pharmazie 2015;70(1):47-54.
- Xing Y, Yu Q, Zhou L, et al. Cytochrome P450-mediated herb-drug interaction (HDI) of Polygonum multiflorum Thunb. based on pharmacokinetic studies and in vitro inhibition assays. Phytomedicine 2023;112:154710.
Interaction Details
Hydrochlorothiazide, Metoprolol is classified as belonging to the following category: Diuretic Drugs
Theoretically, fo-ti, particularly raw fo-ti root, might increase the risk of hypokalemia when taken with diuretic drugs.
Raw fo-ti root contains anthraquinone derivatives, which might have stimulant laxative effects and compound diuretic-induced potassium loss. In vitro research shows that fermented and processed fo-ti root have reduced laxative effects compared with raw fo-ti root.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- Foster S, Tyler VE. Tyler's Honest Herbal: A Sensible Guide to the Use of Herbs and Related Remedies. 3rd ed., Binghamton, NY: Haworth Herbal Press, 1993.
- Laird AR, Ramchandani N, deGoma EM, et al. Acute hepatitis associated with the use of an herbal supplement (Polygonum multiflorum) mimicking iron-overload syndrome. J Clin Gastroenterol 2008;42:861-2.
- Yu J, Xie J, Mao XJ, et al. Comparison of laxative and antioxidant activities of raw, processed and fermented Polygoni multiflori radix. Chin J Nat Med 2012;10(1):63-7.
Fo-ti - More Interactions
Fo-ti interacts with 1215 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
Unknown | No interactions have been reported or no interaction data is currently available. |
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DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
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Drug descriptions are provided by MedlinePlus.