Drug & supplement interaction

Fo-ti + Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine

Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine brand names: Histalet Forte, Poly Hist Forte, Vanex Forte.

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

Fo-ti has a moderate interaction with Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine. Theoretically, fo-ti might increase the levels and clinical effects of drugs metabolized by CYP3A4.

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

Fo-ti and Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine

Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Fo-ti interacts with.

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

This combination product packs an antihistamine pair (chlorpheniramine and pyrilamine) plus a decongestant (phenylephrine). The concern here is fairly mild and mostly theoretical. In lab dish studies, Fo-ti showed it might slow down CYP3A4, one of the liver enzymes that helps clear some of these ingredients. If that happened in a real person, the medicine could linger a bit longer, possibly nudging up familiar effects like drowsiness, dry mouth, dizziness, or a jittery, racing-heart feeling from the decongestant.

That said, this has never been reported in actual people, and animal studies didn't confirm it. So I wouldn't lose sleep over it. Still, if you notice extra grogginess or restlessness, mention it to your pharmacist or doctor before changing anything.

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 1,258 moderate known drug interactions in our database — the Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine one above is one of them. If you take anything else, check it against the full list below.

Moderate 1,258 No known interaction 1,572 (incl. Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine)
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 Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine

This page covers Fo-ti only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine page lists 229 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Ephedra (major), Grapefruit (major), Henbane (major) and Lithium (major).

By severity: 10 major · 175 moderate · 44 minor.

From our pharmacist’s overview on the Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine page

“Ephedra is the first thing I would take off the shelf for anyone using chlorpheniramine, phenylephrine, phenylpropanolamine, and pyrilamine (Histalet Forte, Poly Hist Forte, Vanex Forte). This cold and allergy combination contains two decongestants that already raise blood pressure and heart rate, and 44 ingredients on this list, ephed…”

Reviewed by 2 · Jul 18, 2026

Open the Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine 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 Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine 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 Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine 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%

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

29 days ago today
Medication Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine
Top 5%

#119 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
1,258Moderate
0Minor
1,571No known interaction
1,258 Moderate 1,571 No interaction
Moderate

1,258 interactions

Showing 60 of 1,258 moderate interactions — see all 1,258 on the Fo-ti page.

No interaction 1,571 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 1,571 medications checked with no known interaction — see the full Fo-ti list.

See the full Fo-ti interactions page
See every supplement checked against Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine, 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 Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine supplement interactions › Every supplement checked against Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine, 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 Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine Together: Common Questions

Can you take Fo-ti with Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine?
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 Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine 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 Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine 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.