Drug & supplement interaction

Levilactobacillus Brevis + Valacyclovir

Valacyclovir brand name: Valtrex.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Levilactobacillus Brevis 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. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Levilactobacillus Brevis 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 Levilactobacillus Brevis 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.

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.

Levilactobacillus Brevis safety at a glance

Levilactobacillus... overall Use caution Generally well tolerated in healthy people, but people who are seriously ill or immunocompromised should be cautious.
Pregnancy Use caution Not enough reliable safety data; talk to your doctor before using during pregnancy.
Breastfeeding Use caution Limited data on use while breastfeeding; check with your doctor or pharmacist first.

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

Still wondering about combining Valacyclovir and Levilactobacillus Brevis? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Valacyclovir

Interactions in our licensed database are recorded against drug classes, not just single drug names. Valacyclovir is filed under 3 classifications — organic anion transporter 1 (oat1) substrates, seizure threshold lowering drugs, oral drugs. Levilactobacillus Brevis has documented interactions with 1 drug class — the most serious being antibiotic drugs (moderate) — and none of Valacyclovir’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Levilactobacillus Brevis Does Interact With Other Medications

Levilactobacillus Brevis has 182 moderate known drug interactions in our database — Valacyclovir isn’t one of them. If you take anything else, check it against the full list below.

Moderate 182 No known interaction 2,648 (incl. Valacyclovir)
Taking anything else?

Check Another of Your Medications Against Levilactobacillus Brevis

Covers the 2,830 medications we’ve checked against Levilactobacillus Brevis. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Levilactobacillus Brevis and Valacyclovir May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. One of them is worth acting on rather than waiting out — marked below.

  • A higher chance of infection Worth acting on Additional detail

    Levilactobacillus Brevis

    “Since Levilactobacillus brevis preparations contain live and active microorganisms, there is some concern that they might cause pathogenic infection in some patients. Some lactobacilli species have been isolated in cases of bacteremia, sepsis, splenic abscess, endocarditis, necrotizing fasciitis, pancreatic necrosis, and meningoencephalitis.”

    Levilactobacillus Brevis · Natural Medicines adverse-effect record, reported in sepsis.

    1 source cited
    1. 107543. Rossi F, Amadoro C, Gasperi M, Colavita G. Lactobacilli infection case reports in the last three years and safety implications. Nutrients. 2022;14(6):1178. PubMed

    Valacyclovir

    Listed in the ADVERSE REACTIONS section of the FDA label for Valacyclovir. Read the label on DailyMed ›

  • Diarrhea / Nausea Additional detail

    Levilactobacillus Brevis

    “Orally, taking Levilactobacillus brevis has rarely caused nausea, abdominal fullness, or mild diarrhea, in clinical research.”

    Levilactobacillus Brevis · Natural Medicines adverse-effect record, reported in diarrhea.

    2 sources cited
    1. 110959. Tasli L, Mat C, De Simone C, Yazici H. Lactobacilli lozenges in the management of oral ulcers of Behçet's syndrome. Clin Exp Rheumatol. 2006;24(5 Suppl 42):S83-6.
    2. 110962. Silva NLNV, Della Bona A, Cardoso M, et al. Lactobacillus brevis CD2 attenuates traumatic oral lesions induced by fixed orthodontic appliance: A randomized phase 2 trial. Orthod Craniofac Res. 2021;24(3):379-385.

    Valacyclovir

    Listed in the ADVERSE REACTIONS section of the FDA label for Valacyclovir. Read the label on DailyMed ›

Effects for Valacyclovir come from the ADVERSE REACTIONS section of its FDA label; effects for Levilactobacillus Brevis come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Overlapping uses

What Valacyclovir Is Prescribed For, and What Levilactobacillus Brevis Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Valacyclovir is a prescription medicine with approved uses on its FDA label. Levilactobacillus Brevis is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Valacyclovir is prescribed for: 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.

Levilactobacillus Brevis has been studied for:

  • Genital herpes studied, not established Levilactobacillus Brevis has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Levilactobacillus Brevis for genital herpes

    It is unclear if intravaginal Levilactobacillus brevis is beneficial for genital herpes.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Valacyclovir on your own; if you are taking Levilactobacillus Brevis for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Levilactobacillus Brevis 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 Levilactobacillus Brevis 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 Levilactobacillus Brevis 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 Levilactobacillus Brevis 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 Levilactobacillus Brevis
Steady interest

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

29 days ago today
Medication Valacyclovir
Top 5%

#31 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.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Levilactobacillus Brevis reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Levilactobacillus Brevis and Valacyclovir records this page draws on were last updated July 10, 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 .
Supplement

About Levilactobacillus Brevis

What is Levilactobacillus Brevis?

  • Digestive health
  • Gut microbiome support
  • Immune support
  • Oral and dental health
  • Vaginal health

Levilactobacillus brevis (formerly Lactobacillus brevis) is a lactic acid bacterium found in fermented foods like sauerkraut, pickles, and kimchi, and is used as a probiotic. Early research suggests possible benefits for gut and immune health, but strong human evidence is still limited. It is generally well tolerated in healthy people, but anyone with a weakened immune system or serious illness should talk to a doctor first.

Levilactobacillus brevis · Lactobacillaceae · Whole live bacteria (probiotic strain) · Capsules, tablets, powders, fermented foods, and combination probiotic products

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

Levilactobacillus Brevis: dosing

There is no official standardized dose for Levilactobacillus brevis. Probiotic amounts are usually measured in colony-forming units (CFU), and products vary widely in strength and strain.The best approach is to follow the directions on the product label. Doses are often taken once or twice daily, sometimes with food.

From our Levilactobacillus Brevis monograph — the full record covers uses, side effects and every documented interaction.

Read the full Levilactobacillus Brevis 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 & Levilactobacillus Brevis

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

0Major
182Moderate
0Minor
2,647No known interaction
182 Moderate 2,647 No interaction
Moderate

182 interactions

Showing 60 of 182 moderate interactions — see all 182 on the Levilactobacillus Brevis page.

No interaction 2,647 drugs checked — show the list

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

Showing the 60 most looked-up of 2,647 medications checked with no known interaction — see the full Levilactobacillus Brevis list.

See the full Levilactobacillus Brevis interactions page
See every supplement checked against Valacyclovir, ranked by severity
Evidence & sources

Levilactobacillus Brevis References

The 4 references that drive our Levilactobacillus Brevis monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Pierce A. The American Pharmaceutical Association Practical Guide to Natural Medicines. New York: The Stonesong Press, 1999:19.
  2. Rossi F, Amadoro C, Gasperi M, Colavita G. Lactobacilli infection case reports in the last three years and safety implications. Nutrients. 2022;14(6):1178. PubMed
  3. Tasli L, Mat C, De Simone C, Yazici H. Lactobacilli lozenges in the management of oral ulcers of Behçet's syndrome. Clin Exp Rheumatol. 2006;24(5 Suppl 42):S83-6.
  4. Silva NLNV, Della Bona A, Cardoso M, et al. Lactobacillus brevis CD2 attenuates traumatic oral lesions induced by fixed orthodontic appliance: A randomized phase 2 trial. Orthod Craniofac Res. 2021;24(3):379-385.

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 Levilactobacillus Brevis and Valacyclovir Together: Common Questions

Is it safe to take Levilactobacillus Brevis with Valacyclovir?
We do not list a known interaction between Levilactobacillus Brevis 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.
Do Levilactobacillus Brevis and Valacyclovir have any of the same side effects?
Yes — our sources link each of them separately to 3 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Are Levilactobacillus Brevis and Valacyclovir used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Levilactobacillus Brevis in each. That is a conversation for your prescriber, especially if Valacyclovir is being adjusted to a target.
How was the Levilactobacillus Brevis and Valacyclovir combination checked?
Interactions in our licensed database are recorded against drug classes. Valacyclovir is filed under 3 classifications, and Levilactobacillus Brevis has documented interactions with 1 drug class — none of Valacyclovir's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Levilactobacillus Brevis interact with any other medications?
Yes. Levilactobacillus Brevis has 182 documented drug interactions in our database — Valacyclovir is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Valacyclovir interact with any supplements?
Yes. Valacyclovir has documented interactions with 27 supplements in our database — Levilactobacillus Brevis 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

Levilactobacillus Brevis 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 4 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Valacyclovir and Levilactobacillus Brevis?

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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.