Drug & supplement interaction

Bifidobacterium Breve + Fulvestrant

Fulvestrant brand name: Faslodex.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Bifidobacterium Breve and Fulvestrant 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.

Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Bifidobacterium Breve and Fulvestrant

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 Fulvestrant and Bifidobacterium Breve 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 Breve safety at a glance

Bifidobacterium Br... overall Use caution Generally well tolerated in healthy people, but caution is needed for those who are very ill or immunocompromised.
Pregnancy Use caution Probiotics are often considered low-risk, but evidence is limited, so use only with your doctor's guidance.
Breastfeeding Use caution Limited safety data exist, so check with your healthcare provider before use.

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

Still wondering about combining Fulvestrant and Bifidobacterium Breve? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Fulvestrant

Interactions in our licensed database are recorded against drug classes, not just single drug names. Fulvestrant is filed under a single classification. Bifidobacterium Breve has documented interactions with 1 drug class — the most serious being antibiotic drugs (moderate) — and none of Fulvestrant’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

Bifidobacterium Breve Does Interact With Other Medications

Bifidobacterium Breve has 182 moderate known drug interactions in our database — Fulvestrant 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. Fulvestrant)
Taking anything else?

Check Another of Your Medications Against Bifidobacterium Breve

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

What to actually watch for

What Bifidobacterium Breve Itself Has Been Linked To

This is not an interaction — nothing below involves Fulvestrant. It is the side-effect record for Bifidobacterium Breve on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Bifidobacterium Breve, this list is the first place to look. One entry is worth acting on rather than waiting out — marked below.

  • A bowel blockage / A higher chance of infection Worth acting on Additional detail

    “There have been rare cases of Bifidobacterium bacteremia related to probiotic use in critically ill infants and adults. In addition, cases of B. breve bacteremia have occurred in preterm infants or young children using probiotics. In a review of 298 term and preterm infants who were admitted to the neonatal intensive care unit of a hospital in Japan and received B.”

    Bifidobacterium Breve · Natural Medicines adverse-effect record, reported in diabetes.

    6 sources cited
    1. 102416. 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.
    2. 107597. Sakurai Y, Watanabe T, Miura Y, et al. Clinical and bacteriologic characteristics of six cases of Bifidobacterium breve bacteremia due to probiotic administration in the neonatal intensive care unit. Pediatr Infect Dis J 2022;41(1):62-65. PubMed
    3. 107599. 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
    4. 107596. Ohishi A, Takahashi S, Ito Y, et al. Bifidobacterium septicemia associated with postoperative probiotic therapy in a neonate with omphalocele. J Pediatr. 2010;156(4):679-81. PubMed
    5. 111007. Wakabayashi Y, Nakayama S, Yamamoto A, et al. First case of necrotizing fasciitis and bacteremia caused by Bifidobacteriumbreve. Anaerobe 2022;76:102613.
    6. 111011. Takeda Y, Ota K, Kondo A, et al. A case of necrotizing fasciitis caused by Bifidobacterium breve. IDCases 2022;31:e01667. PubMed
  • Bloating or gas Additional detail

    “Bloating and flatulence have been reported with probiotic use; however, these adverse effects have not been reported from ingestion of Bifidobacterium breve in particular.”

    Bifidobacterium Breve · Natural Medicines adverse-effect record, reported in flatulence.

Everything above comes from the Natural Medicines adverse-effect record for Bifidobacterium Breve — expand a row for the licensed statement it rests on. We read the ADVERSE REACTIONS section of Fulvestrant’s FDA label too, and the two lists don’t meaningfully overlap — which is why no Fulvestrant column appears here.

Everything else you take

See Every Supplement That Interacts With Fulvestrant

This page covers Bifidobacterium Breve only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fulvestrant page lists 1 supplement it has a documented interaction with, worst first, each one explained.

The most serious there right now: Dhea (moderate).

By severity: 1 moderate.

Open the Fulvestrant interaction page

One more smart check

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

We hold 1,771 real supplement products containing Bifidobacterium Breve, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Bifidobacterium Breve. Even though Bifidobacterium Breve itself has no known interaction with Fulvestrant, 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 Breve and Fulvestrant 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 Breve
Top 25%

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

29 days ago today
Medication Fulvestrant
Steady interest

#1,418 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 Breve reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Bifidobacterium Breve and Fulvestrant 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 Breve

What is Bifidobacterium Breve?

  • Digestive health and regularity
  • Infant colic and gut support
  • Diarrhea (including antibiotic-related)
  • Constipation
  • General immune and gut microbiome support

Bifidobacterium breve is a 'friendly' gut bacterium taken as a probiotic, most often to support digestion and balance the gut microbiome. Some studies suggest possible benefits for certain digestive and infant conditions, but evidence is still limited and varies by strain. It is generally well tolerated in healthy people, but anyone with a weak immune system or serious illness should check with a doctor or pharmacist first.

Bifidobacterium breve · Bifidobacteriaceae · Live bacterial cells (probiotic strain) · Capsules, powders, sachets, chewables, drops, and fortified foods or drinks

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

Bifidobacterium Breve: dosing

There is no single standard dose of Bifidobacterium breve. Probiotic amounts are usually measured in colony-forming units (CFU), and products vary widely in their strain and strength.The best approach is to follow the directions on the product label, since dosing was often based on the specific strain studied.

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

Read the full Bifidobacterium Breve monograph & all interactions
Medication

About Fulvestrant Injection

What Is Fulvestrant Injection Used For?

Brand name: Faslodex

Fulvestrant injection treats hormone receptor (HR)-positive advanced breast cancer in postmenopausal women. It can be used alone for women who have not yet had endocrine (hormone-blocking) therapy, or for women whose cancer has grown despite endocrine therapy.

It is also used in combination with other medicines — palbociclib, abemaciclib, or ribociclib — for HR-positive, HER2-negative advanced or metastatic breast cancer in women whose disease has progressed after endocrine therapy. Fulvestrant injection combined with ribociclib may also be used as an initial hormone-based treatment in this setting.

Most-Reported Side Effects for Fulvestrant

From FAERS, the FDA’s public side-effect reporting system (32,843 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Malignant neoplasm progression 4,229 reports
Fatigue 4,182 reports
Nausea 3,029 reports
Diarrhea 2,623 reports
Neutropenia 2,485 reports
See full Fulvestrant Injection drug information
Keep checking

Other Drugs & Bifidobacterium Breve

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

No interaction 2,647 drugs checked — show the list

We also checked Bifidobacterium Breve 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 Breve list.

See the full Bifidobacterium Breve interactions page
See every supplement checked against Fulvestrant, ranked by severity
Evidence & sources

Bifidobacterium Breve References

The 9 references that drive our Bifidobacterium Breve 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. 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
  3. 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.
  4. Ohishi A, Takahashi S, Ito Y, et al. Bifidobacterium septicemia associated with postoperative probiotic therapy in a neonate with omphalocele. J Pediatr. 2010;156(4):679-81. PubMed
  5. Sakurai Y, Watanabe T, Miura Y, et al. Clinical and bacteriologic characteristics of six cases of Bifidobacterium breve bacteremia due to probiotic administration in the neonatal intensive care unit. Pediatr Infect Dis J 2022;41(1):62-65. PubMed
  6. 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
  7. Wakabayashi Y, Nakayama S, Yamamoto A, et al. First case of necrotizing fasciitis and bacteremia caused by Bifidobacteriumbreve. Anaerobe 2022;76:102613.
  8. Takeda Y, Ota K, Kondo A, et al. A case of necrotizing fasciitis caused by Bifidobacterium breve. IDCases 2022;31:e01667. PubMed
  9. Suwantarat N, Romagnoli M, Wakefield T, Carroll KC. Ventriculoperitoneal shunt infection caused by Bifidobacterium breve. Anaerobe 2014;28:1-3. PubMed

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 Breve and Fulvestrant Together: Common Questions

Is it safe to take Bifidobacterium Breve with Fulvestrant?
We do not list a known interaction between Bifidobacterium Breve and Fulvestrant. 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.
How was the Bifidobacterium Breve and Fulvestrant combination checked?
Interactions in our licensed database are recorded against drug classes. Fulvestrant is filed under 1 classification, and Bifidobacterium Breve has documented interactions with 1 drug class — none of Fulvestrant'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 Bifidobacterium Breve interact with any other medications?
Yes. Bifidobacterium Breve has 182 documented drug interactions in our database — Fulvestrant 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 Fulvestrant interact with any supplements?
Yes. Fulvestrant has documented interactions with 1 supplement in our database — Bifidobacterium Breve is not one of them. The Fulvestrant 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

Bifidobacterium Breve monograph Uses, safety profile, and every drug interaction in one place Fulvestrant Injection drug information The full plain-English guide to this medication Fulvestrant supplement interactions Every supplement checked against Fulvestrant, 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 9 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Fulvestrant and Bifidobacterium Breve?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.