Drug & supplement interaction

Fo-ti + Etonogestrel

Etonogestrel brand name: Implanon.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Etonogestrel falls into 3 drug categories that Fo-ti can interact with; the most serious is rated moderate. Theoretically, fo-ti might increase or decrease the levels and clinical effects of drugs metabolized by CYP1A2.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions3
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Fo-ti and Etonogestrel

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Fo-ti interacts with whole categories of medication. Etonogestrel falls into 3 of those categories, so it can interact with Fo-ti in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

1 of 3

Why this applies to Etonogestrel

Etonogestrel falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES — the group Fo-ti interacts with.

Theoretically, fo-ti might increase or decrease the levels and clinical effects of drugs metabolized by CYP1A2.
In vitro research suggests that fo-ti might inhibit CYP1A2. Additionally, in vitro research suggests that the degree of CYP1A2 inhibition depends on the type of fo-ti extract (i.e., the raw plant leads to greater inhibition than extensively processed extracts). However, in an animal study, an aqueous extract of fo-ti inhibited CYP1A2 while an alcoholic extract of fo-ti induced CYP1A2. Induction or inhibition of CYP1A2 by fo-ti has not been reported in humans.
Severity Moderate Likelihood Possible Evidence D

Interaction 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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

If you have the etonogestrel implant (Implanon or Nexplanon), here's the honest picture. The interaction on file is about an enzyme called CYP1A2, and lab tests suggest Fo-ti might either block or speed up that enzyme depending on how it's prepared. The catch is that etonogestrel is mostly handled by a different liver enzyme (CYP3A4), so CYP1A2 plays only a minor role in its breakdown.

Because of that, I wouldn't expect Fo-ti to meaningfully change how well your implant prevents pregnancy. This is a theoretical concern from cell and animal studies, with nothing seen in real people. Still, since Fo-ti has been tied to liver problems, please run it past your pharmacist or doctor before starting it.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Unger M, Frank A. Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction. Rapid Commun Mass Spectrom 2004;1 PubMed
  2. 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. DOI
  3. 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. PubMed
Moderate

CONTRACEPTIVE DRUGS

2 of 3

Etonogestrel also falls under CONTRACEPTIVE DRUGS.

Theoretically, taking large amounts of fo-ti might interfere with contraceptive drugs due to competition for estrogen receptors.
In vitro research suggests that fo-ti extract has estrogenic activity.
Severity Moderate Likelihood Probable Evidence D

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the situation with the Implanon implant (etonogestrel) and Fo-ti. Etonogestrel is a progestin that prevents pregnancy, and it works on its own (it doesn't need your body to activate it first). The concern on file is that Fo-ti may have mild estrogen-like activity in lab studies, and in theory large supplement amounts could compete at hormone receptors and nudge how well your birth control does its job.

I want to be honest: this is a theoretical worry based only on test-tube research, not real-world cases of people getting pregnant on the implant. Still, since an unplanned pregnancy is a big deal, I'd play it safe. Before starting concentrated Fo-ti, check in with your pharmacist or prescriber, and consider a backup method if you're worried.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Oerter Klein KO, Janfaza M, Wong JA, Chang RJ. Estrogen bioactivity in Fo-Ti and other herbs used for their estrogen-like effects as determined by a recombinant cell bioassay. J Clin Endocrinol Metab 2003;88:4077-9.. PubMed
  2. Zhang CZ, Wang SX, Zhang Y, et al. In vitro estrogenic activities of Chinese medicinal plants traditionally used for the management of menopausal symptoms. J Ethnopharmacol 2005;98:295-300. PubMed
  3. Kang, S. C., Lee, C. M., Choi, H., Lee, J. H., Oh, J. S., Kwak, J. H., and Zee, O. P. Evaluation of oriental medicinal herbs for estrogenic and antiproliferative activities. Phytother Res 2006;20(11):1017-1019. PubMed
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

3 of 3

Etonogestrel also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, fo-ti might increase the levels and clinical effects of drugs metabolized by CYP3A4.
In vitro research suggests that fo-ti might inhibit CYP3A4. One in vitro study suggests that the degree of CYP3A4 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 evidence conflicts with animal research suggesting that fo-ti does not inhibit CYP3A4. This interaction has not been reported in humans.
Severity Moderate Likelihood Possible Evidence D

Interaction 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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Etonogestrel, the hormone in the Implanon (and Nexplanon) implant, gets broken down by a liver enzyme called CYP3A4. Lab studies hint that Fo-ti might slow that enzyme down, which in theory could let a bit more etonogestrel build up in your body. If anything, that means slightly stronger hormone effects, things like spotting or irregular bleeding, breast tenderness, headaches, or mood changes.

Here's the reassuring part: this is only a theoretical concern from test-tube research, and animal studies didn't agree. It has never been reported in real people, and the implant releases a low, steady dose anyway. Still, since Fo-ti has been tied to liver injury, it's worth a quick chat with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Unger M, Frank A. Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction. Rapid Commun Mass Spectrom 2004;1 PubMed
  2. 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. DOI
  3. 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. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • 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.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Fo-ti Also Interacts With Other Medications

Fo-ti has 1,256 moderate known drug interactions in our database — the Etonogestrel one above is among them. If you take anything else, check it against the full list below.

Moderate 1,256 No known interaction 1,574 (incl. Etonogestrel)
Taking anything else?

Check Another of Your Medications Against Fo-ti

Covers the 2,830 medications we’ve checked against Fo-ti. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Etonogestrel

This page covers Fo-ti only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Etonogestrel page lists 175 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Grapefruit (major), St. John's Wort (major), Acacia Rigidula (moderate), Activated Charcoal (moderate) and Adrafinil (moderate).

By severity: 2 major · 135 moderate · 38 minor.

From our pharmacist’s overview on the Etonogestrel page

“St. John's wort is the supplement to understand first if you use etonogestrel (Implanon), because it revs up the liver enzyme that clears the hormone and can leave you with less pregnancy protection than you think you have.”

Reviewed by 2 · Jul 18, 2026

Open the Etonogestrel interaction page

One more smart check

Taking Fo-ti as Part of a Dietary Supplement Product? Check It for Interactions

We hold 976 real supplement products containing Fo-ti, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Fo-ti. Your product may carry other ingredients that interact with Etonogestrel too, on top of Fo-ti — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Fo-ti and Etonogestrel Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Fo-ti
Top 25%

#210 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Etonogestrel
Steady interest

#1,973 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Fo-ti

What is Fo-ti?

  • Anti-aging and longevity
  • Hair graying and hair loss
  • General tonic for vitality
  • Constipation
  • High cholesterol

Fo-ti (He Shou Wu) is a root used in traditional Chinese medicine, often promoted for healthy aging and hair. High-quality human evidence for these benefits is limited, and processed Fo-ti has been linked to reports of liver injury, so caution and professional guidance are important.

Read the full Fo-ti monograph & all interactions
Keep checking

Other Drugs & Fo-ti

Browse every other medication we’ve checked against Fo-ti — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
1,256Moderate
0Minor
1,573No known interaction
1,256 Moderate 1,573 No interaction
Moderate

1,256 interactions

Showing 60 of 1,256 moderate interactions — see all 1,256 on the Fo-ti page.

No interaction 1,573 drugs checked — show the list

We also checked Fo-ti against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,573 medications checked with no known interaction — see the full Fo-ti list.

See the full Fo-ti interactions page
See every supplement checked against Etonogestrel, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

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.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Fo-ti monograph › Uses, safety, and every drug interaction in one place Etonogestrel supplement interactions › Every supplement checked against Etonogestrel, ranked by severity Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Fo-ti and Etonogestrel Together: Common Questions

Can you take Fo-ti with Etonogestrel?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 3 interactions listed for Fo-ti and Etonogestrel?
Etonogestrel belongs to more than one drug category, and Fo-ti interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Fo-ti and Etonogestrel interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Etonogestrel and Fo-ti?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.