Drug & supplement interaction

Bifidobacterium Longum + Letermovir (IV)

Letermovir (IV) brand name: Prevymis.

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 Bifidobacterium Longum and Letermovir (IV) 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

Bifidobacterium Longum and Letermovir (IV)

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 Letermovir (IV) and Bifidobacterium Longum 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.

Bifidobacterium Longum safety at a glance

Bifidobacterium Lo... overall Use caution Generally well tolerated in healthy people, but caution is needed for those who are seriously ill or immune-compromised.
Pregnancy Possibly Safe When used orally and appropriately, short-term. A combination of Bifidobacterium longum and Lacticaseibacillus rhamnosus has been used with apparent safety thro... Read the full pregnancy detail
Breastfeeding Possibly Safe When used orally and appropriately, short-term. A combination of Bifidobacterium longum and Lacticaseibacillus rhamnosus has been used with apparent safety thro... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Letermovir (IV) and Bifidobacterium Longum? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
Keep it in perspective

Bifidobacterium Longum Does Interact With Other Medications

Bifidobacterium Longum has 182 moderate known drug interactions in our database — Letermovir (IV) 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. Letermovir (IV))
Taking anything else?

Check Another of Your Medications Against Bifidobacterium Longum

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

What to actually watch for

No Interaction Found — But Data Suggests Bifidobacterium Longum and Letermovir (IV) May Share a Side Effect

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.

  • Cough Additional detail

    Bifidobacterium Longum

    “When taken orally, a dry cough has been reported by a single patient in a clinical trial.”

    Bifidobacterium Longum · Natural Medicines adverse-effect record, reported in cough.

    1 source cited
    1. 111851. Tamaki H, Nakase H, Inoue S, et al. Efficacy of probiotic treatment with Bifidobacterium longum 536 for induction of remission in active ulcerative colitis: A randomized, double-blinded, placebo-controlled multicenter trial. Dig Endosc 2016;28(1):67-74.

    Letermovir (IV)

    Listed in the ADVERSE REACTIONS section of the FDA label for Letermovir (IV). Read the label on DailyMed ›

Reported for Bifidobacterium Longum but not commonly for Letermovir (IV): stomach upset, constipation, bloating or gas and a higher chance of infection.

Effects for Letermovir (IV) come from the ADVERSE REACTIONS section of its FDA label; effects for Bifidobacterium Longum 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.

Special populations

Bifidobacterium Longum in Pregnancy & Breastfeeding

Pregnancy And Lactation Possibly Safe

When used orally and appropriately, short-term. A combination of Bifidobacterium longum and Lacticaseibacillus rhamnosus has been used with apparent safety throughout pregnancy. A combination of B. longum BB536 and Bifidobacterium breve M-16V has been used with apparent safety from about 4 weeks before the expected due date until delivery. Also, a combination of B. longum and Lacticaseibacillus paracasei has been used with apparent safety from 2 months prior to delivery until 2 months after delivery during lactation.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

One more smart check

Taking Bifidobacterium Longum as Part of a Dietary Supplement Product? Check It for Interactions

We hold 3,189 real supplement products containing Bifidobacterium Longum, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Bifidobacterium Longum. Even though Bifidobacterium Longum itself has no known interaction with Letermovir (IV), another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Bifidobacterium Longum and Letermovir (IV) 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 Bifidobacterium Longum
Top 10%

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

29 days ago today
Medication Letermovir (IV)
Top 25%

#339 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 Bifidobacterium Longum reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Bifidobacterium Longum and Letermovir (IV) 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 Bifidobacterium Longum

What is Bifidobacterium Longum?

  • Digestive health and regularity
  • Irritable bowel syndrome (IBS)
  • Diarrhea (including antibiotic-related)
  • Immune support
  • Mood and stress (gut-brain axis)

Bifidobacterium longum is a 'friendly' bacterium found naturally in the human gut and used as a probiotic. It is generally well tolerated and is most studied for digestive issues, though evidence for many uses is still limited or mixed. Talk to your pharmacist or doctor before using it, especially if you have a weakened immune system.

Bifidobacterium longum · Bifidobacteriaceae · Live bacterial cells (probiotic) · Capsules, tablets, powders, sachets, fermented foods, and multi-strain probiotic blends

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

Bifidobacterium Longum: dosing

There is no single established 'correct' dose for Bifidobacterium longum. Probiotic doses are usually measured in colony-forming units (CFU), and products vary widely in how many CFU they contain and which strains they include.The best approach is to follow the directions on your specific product's label. Keep the product stored as directed (some need refrigeration) to keep the bacteria alive and effective.

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

Read the full Bifidobacterium Longum monograph & all interactions
Medication

About Letermovir Injection

What Is Letermovir Injection Used For?

Brand name: Prevymis

Prevymis injection is used to prevent cytomegalovirus (CMV) infection and disease in adults and children 6 months of age and older (weighing at least 6 kg) who have received an allogeneic hematopoietic stem cell transplant (HSCT) and are CMV-seropositive (meaning they carry the CMV virus).

Prevymis injection is also used to prevent CMV disease in adults and children 12 years of age and older (weighing at least 40 kg) who have received a kidney transplant and are at high risk — specifically when the donor tested positive for CMV but the recipient tested negative (D+/R-).

See full Letermovir Injection drug information
Keep checking

Other Drugs & Bifidobacterium Longum

Browse every other medication we’ve checked against Bifidobacterium Longum — 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 Bifidobacterium Longum page.

No interaction 2,647 drugs checked — show the list

We also checked Bifidobacterium Longum 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 Bifidobacterium Longum list.

See the full Bifidobacterium Longum interactions page
See every supplement checked against Letermovir (IV), ranked by severity
Evidence & sources

Bifidobacterium Longum References

The 21 references that drive our Bifidobacterium Longum 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. Ha GY, Yang CH, Kim H, Chong Y. Case of sepsis caused by Bifidobacterium longum. J Clin Microbiol 1999;37:1227-8.
  2. Pierce A. The American Pharmaceutical Association Practical Guide to Natural Medicines. New York: The Stonesong Press, 1999:19.
  3. Xiao JZ, Takahashi S, Odamaki T, et al. Antibiotic susceptibility of bifidobacterial strains distributed in the Japanese market. Biosci Biotechnol Biochem. 2010;74(2):336-42. PubMed
  4. Rautava S, Kainonen E, Salminen S, Isolauri E. Maternal probiotic supplementation during pregnancy and breast-feeding reduces the risk of eczema in the infant. J Allergy Clin Immunol. 2012;130(6):1355-60. PubMed
  5. Pruccoli G, Silvestro E, Pace Napoleone C, Aidala E, Garazzino S, Scolfaro C. Are probiotics safe? Bifidobacterium bacteremia in a child with severe heart failure. Infez Med. 2019;27(2):175-178.
  6. Pellonperä O, Vahlberg T, Mokkala K, et al. Weight gain and body composition during pregnancy: a randomised pilot trial with probiotics and/or fish oil. Br J Nutr. 2020 Nov 4:1-11. PubMed
  7. Pellonperä O, Mokkala K, Houttu N, et al. Efficacy of fish oil and/or probiotic intervention on the incidence of gestational diabetes mellitus in an at-risk group of overweight and obese women: A randomized, placebo-controlled, double-blind clinical trial PubMed
  8. Shahriari A, Karimi E, Shahriari M, Aslani N, Khooshideh M, Arab A. The effect of probiotic supplementation on the risk of gestational diabetes mellitus among high-risk pregnant women: A parallel double-blind, randomized, placebo-controlled clinical trial PubMed
  9. Esaiassen E, Hjerde E, Cavanagh JP, Simonsen GS, Klingenberg C; Norwegian Study Group on Invasive Bifidobacterial Infections. Bifidobacterium bacteremia: Clinical characteristics and a genomic approach to assess pathogenicity. J Clin Microbiol. 2017;55(7) PubMed
  10. Enomoto T, Sowa M, Nishimori K, et al. Effects of bifidobacterial supplementation to pregnant women and infants in the prevention of allergy development in infants and on fecal microbiota. Allergol Int 2014;63(4):575-85. PubMed
  11. US Food and Drug Administration (FDA). Dear Healthcare Provider Letter: Warning Regarding Use of Probiotics in Preterm Infants. September 2023. Available at: https://www.fda.gov/media/172606/download?attachment. Accessed November 1, 2023.
  12. Pillai A, Tan J, Paquette V, Panczuk J. Does probiotic bacteremia in premature infants impact clinically relevant outcomes? A case report and updated review of literature. Clin Nutr ESPEN. 2020;39:255-259. PubMed
  13. Sabaté JM, Iglicki F. Effect of Bifidobacterium longum 35624 on disease severity and quality of life in patients with irritable bowel syndrome. World J Gastroenterol 2022;28(7):732-744.
  14. Malaguarnera M, Greco F, Barone G, Gargante MP, Malaguarnera M, Toscano MA. Bifidobacterium longum with fructo-oligosaccharide (FOS) treatment in minimal hepatic encephalopathy: a randomized, double-blind, placebo-controlled study. Dig Dis Sci 2007;52(11) PubMed
  15. Zbinden A, Zbinden R, Berger C, Arlettaz R. Case series of Bifidobacterium longum bacteremia in three preterm infants on probiotic therapy. Neonatology 2015;107(1):56-9.

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 Bifidobacterium Longum and Letermovir (IV) Together: Common Questions

Is it safe to take Bifidobacterium Longum with Letermovir (IV)?
We do not list a known interaction between Bifidobacterium Longum and Letermovir (IV). 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 Bifidobacterium Longum and Letermovir (IV) have any of the same side effects?
Yes — our sources link each of them separately to one 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.
Does Bifidobacterium Longum interact with any other medications?
Yes. Bifidobacterium Longum has 182 documented drug interactions in our database — Letermovir (IV) is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.

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

Where next

Keep Exploring

Bifidobacterium Longum monograph Uses, safety profile, and every drug interaction in one place Letermovir Injection drug information The full plain-English guide to this medication Letermovir (IV) supplement interactions Every supplement checked against Letermovir (IV), 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 21 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

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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.