Drug & supplement interaction

Fo-ti + Atovaquone, Proguanil

Atovaquone, Proguanil brand name: Malarone.

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

Fo-ti has a moderate interaction with Atovaquone, Proguanil. Theoretically, fo-ti may increase the levels and clinical effects of drugs metabolized by CYP2C19.

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

Fo-ti and Atovaquone, Proguanil

Here is the interaction we found between these two, with the evidence behind it.

Moderate

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES

Why this applies to Atovaquone, Proguanil

Atovaquone, Proguanil falls under CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES — the group Fo-ti interacts with.

Theoretically, fo-ti may increase the levels and clinical effects of drugs metabolized by CYP2C19.
Animal and in vitro research suggests that fo-ti may inhibit CYP2C19. An in vitro study suggests that the degree of CYP2C19 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.
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

Here's the part of Malarone that matters here: the proguanil piece is actually a prodrug. Your liver uses an enzyme called CYP2C19 to convert proguanil into its active form, cycloguanil, which is what helps fight the malaria parasite. Fo-ti has shown, in lab and animal studies only, that it might slow that same enzyme down.

If that happened in people, you could end up making less of the active form, which in theory could make Malarone work less well for preventing or treating malaria. That's a real concern when you're relying on it to stay safe in a malaria area. Honestly though, this hasn't been seen in humans, and processed Fo-ti seems to block the enzyme far less than the raw root. Still, I'd run it by your doctor or pharmacist before traveling rather than risk 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

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 Atovaquone, Proguanil one above is one of them. If you take anything else, check it against the full list below.

Moderate 1,256 No known interaction 1,574 (incl. Atovaquone, Proguanil)
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 Atovaquone, Proguanil

This page covers Fo-ti only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Atovaquone, Proguanil page lists 54 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Adrafinil (moderate), Artichoke (moderate), Bacopa (moderate) and Baikal Skullcap (moderate).

By severity: 1 major · 40 moderate · 13 minor.

From our pharmacist’s overview on the Atovaquone, Proguanil page

“Most people taking atovaquone-proguanil (Malarone) are travelers trying to prevent malaria, so this list of 54 interacting supplements deserves real attention, since anything that weakens the drug can leave you exposed to the disease itself. The single major-rated entry is activated charcoal, a common travel remedy for stomach upset, w…”

Reviewed by 2 · Jul 18, 2026

Open the Atovaquone, Proguanil 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 Atovaquone, Proguanil 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 Atovaquone, Proguanil 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%

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

29 days ago today
Medication Atovaquone, Proguanil
Steady interest

#2,139 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
Medication

About Atovaquone and Proguanil

What Is Atovaquone and Proguanil Used For?

Brand name: Malarone

Atovaquone and proguanil is used for two purposes: preventing P. falciparum malaria before and during travel to areas where malaria is common, and treating an active, uncomplicated P. falciparum malaria infection. This includes regions where other antimalarials — such as chloroquine, mefloquine, halofantrine, and amodiaquine — may no longer be effective due to drug resistance.

Both the adult-strength and pediatric-strength tablet formulations share these same two approved uses. The brand Malarone is approved for both prevention and treatment of P. falciparum malaria in adults and in pediatric patients, with dosing based on body weight for children.

See full Atovaquone and Proguanil drug information
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 Atovaquone, Proguanil, 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 Atovaquone, Proguanil supplement interactions › Every supplement checked against Atovaquone, Proguanil, ranked by severity Atovaquone and Proguanil drug information › The full plain-English guide to this medication 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 Atovaquone, Proguanil Together: Common Questions

Can you take Fo-ti with Atovaquone, Proguanil?
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.
How serious is the Fo-ti and Atovaquone, Proguanil 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 Atovaquone, Proguanil 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.