Drug & supplement interaction

European Five-finger Grass + Valacyclovir

Valacyclovir brand name: Valtrex.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated June 2026 · Pair last verified Sep 13, 2026

The bottom line No known interaction

We found no known interaction between European Five-finger Grass and Valacyclovir in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first.

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Interaction report

European Five-finger Grass and Valacyclovir

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Valacyclovir and European Five-finger Grass in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

Worth understanding: our licensed dataset holds no drug-interaction record for European Five-finger Grass at all — not against Valacyclovir, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

European Five-finger Grass safety at a glance

European Five-fing... overall Use caution Limited safety data exist, so use it cautiously and at modest amounts.

Pregnancy Avoid Not enough safety information is available, so it is best avoided during pregnancy.

Breastfeeding Avoid Safety while breastfeeding is unknown, so avoid use unless cleared by your doctor.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Valacyclovir and European Five-finger Grass? Ask Dr. Brian Staiger, PharmD, BCPS directly ›

What to actually watch for

What Valacyclovir’s Own FDA Label Lists

This is not an interaction — none of it involves European Five-finger Grass. These are the most notable effects listed in the ADVERSE REACTIONS section of Valacyclovir’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both. 10 of them are worth acting on rather than waiting out — marked below.

Mania or an unusually elevated mood Worth acting on
Dehydration Worth acting on
Unsteadiness Worth acting on
Hallucinations Worth acting on
Confusion Worth acting on
A severe skin reaction Worth acting on
Seizures Worth acting on
Low mood Worth acting on
A low platelet count Worth acting on
Kidney problems Worth acting on

Showing the 10 most notable of 35 label-listed effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

From the ADVERSE REACTIONS section of the FDA label for Valacyclovir. Read the label on DailyMed › European Five-finger Grass’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no European Five-finger Grass side to compare — that is a limit of the record, not a statement that European Five-finger Grass has no side effects.

From our Q&A

Questions About European Five-finger Grass or Valacyclovir

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers European Five-finger Grass or Valacyclovir, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Valacyclovir

This page covers European Five-finger Grass only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Valacyclovir page lists 27 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), African Wild Potato (moderate), Banderol (moderate), Biofeedback (moderate) and Caffeic Acid (moderate).

By severity: 1 major · 17 moderate · 9 minor.

From our pharmacist’s overview on the Valacyclovir page

“Valacyclovir (Valtrex) works against herpes outbreaks only if enough of it gets absorbed into your blood, and most of this list threatens exactly that. Of the 27 supplements on file, 17 can change how well oral medicines like this one are absorbed, and the single major-rated entry, activated charcoal, binds drugs in the gut outright.”

Reviewed by 2 · Jul 18, 2026

Open the Valacyclovir interaction page

How much people look this up

Where European Five-finger Grass and Valacyclovir 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 European Five-finger Grass

Steady interest

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

29 days ago today

Medication Valacyclovir

Top 5%

#30 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.

Where does our data come from?

Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions. European Five-finger Grass is not yet covered by that licensed database, so its write-up cites publicly available medical sources directly (see the references below).
Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every European Five-finger Grass reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The European Five-finger Grass and Valacyclovir records this page draws on were last updated June 22, 2026.
What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.

Data structure & sourcing designed and verified by Dr. Brian Staiger, PharmD, BCPS.

Supplement

About European Five-finger Grass

What is European Five-finger Grass?

Diarrhea
Sore throat and mouth rinse
Skin irritation
Mild inflammation
Digestive upset

European Five-finger Grass (Potentilla reptans) is a traditional European herb used mainly for diarrhea, sore throat, and minor skin problems, largely because of its tannin content. There is very little high-quality human research to confirm it works for any condition, so use it cautiously and talk to your pharmacist or doctor first.

Potentilla reptans · Rosaceae · Leaves, flowers, and roots (aerial parts and rhizome) · Tea, liquid extract, tincture, dried herb, topical preparations

An interaction check asks whether these two react with each other — it does not ask whether European Five-finger Grass is a good idea for someone in your situation. Here is what our European Five-finger Grass record says about it on its own.

European Five-finger Grass: dosing

There is no standardized, scientifically established dose for European Five-finger Grass. Traditional use most often involved a tea made from the dried leaves or roots, but exact amounts varied widely.If you choose to use a commercial product, follow the directions on the label and do not exceed the recommended amount. Because product strength can vary a lot between brands, it is wise to start low.

From our European Five-finger Grass monograph — the full record covers uses, side effects and every documented interaction.

Read the full European Five-finger Grass monograph & all interactions

Medication

About Valacyclovir

What Is Valacyclovir Used For?

Brand name: Valtrex

Valacyclovir tablets are used in adults to treat cold sores (herpes labialis), genital herpes (initial and recurrent episodes), and shingles (herpes zoster). They can also be taken daily as suppressive therapy to reduce how often genital herpes outbreaks occur, and to lower the risk of passing genital herpes to a partner.

In children and adolescents, valacyclovir tablets are used to treat cold sores in those aged 12 and older, and chickenpox in those aged 2 to under 18. Valacyclovir has not been established as safe and effective for most uses in immunocompromised patients, with the exception of suppressive therapy for genital herpes in HIV-infected adults.

Most-Reported Side Effects for Valacyclovir

From FAERS, the FDA’s public side-effect reporting system (70,056 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 4,317 reports

Nausea 3,985 reports

Diarrhea 3,648 reports

Headache 2,964 reports

Fever 2,753 reports

See full Valacyclovir drug information

Keep checking

Other Drugs & European Five-finger Grass

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

0Major

0Moderate

0Minor

2,829No known interaction

2,829 No interaction

No interaction 2,829 drugs checked — show the list

We also checked European Five-finger Grass against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full European Five-finger Grass list.

See the full European Five-finger Grass interactions page

See every supplement checked against Valacyclovir, ranked by severity

Evidence & sources

European Five-finger Grass References

The 2 sources that drive our European Five-finger Grass monograph — publicly available pages from reputable medical and government organizations. Every link was verified to work before publishing. European Five-finger Grass is not covered by the licensed Natural Medicines interaction database, so its page cites these public sources directly.

Herbs at a Glance — NIH National Center for Complementary and Integrative Health Source
Herbs and Supplements — MedlinePlus Source

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking European Five-finger Grass and Valacyclovir Together: Common Questions

Is it safe to take European Five-finger Grass with Valacyclovir?

We do not list a known interaction between European Five-finger Grass and Valacyclovir. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.

Does Valacyclovir interact with any supplements?

Yes. Valacyclovir has documented interactions with 27 supplements in our database — European Five-finger Grass is not one of them. The Valacyclovir interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

European Five-finger Grass monograph Uses, safety profile, and every drug interaction in one place Valacyclovir drug information The full plain-English guide to this medication Valacyclovir supplement interactions Every supplement checked against Valacyclovir, 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 References The 2 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Valacyclovir and European Five-finger Grass?

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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.