Drug & supplement interaction

Lactobacillus Acidophilus + Phenylephrine

Phenylephrine brand names: Gilchew, AH Chew D, Gilchew IR, Sudafed PE, Biorphen.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Oct 4, 2026

The bottom line No known interaction

We found no known interaction between Lactobacillus Acidophilus and Phenylephrine 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.

Know someone taking this? Share

Facebook Post Reddit Email

On this page

Interaction report

Lactobacillus Acidophilus and Phenylephrine

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 Phenylephrine and Lactobacillus Acidophilus 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.

Lactobacillus Acidophilus safety at a glance

Lactobacillus Acid... overall Generally safe Generally well tolerated in healthy adults and children.

Pregnancy Possibly Safe When used orally and appropriately. A combination of Lactobacillus acidophilus, Lacticaseibacillus casei, and Bifidobacterium bifidum has been used with apparen... Read the full pregnancy detail

Breastfeeding Use caution Likely low risk, but data are limited so ask your healthcare provider.

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 Phenylephrine and Lactobacillus Acidophilus? Ask Dr. Brian Staiger, PharmD, BCPS directly ›

How we checked

Why No Interaction Is Listed for Phenylephrine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Phenylephrine is filed under 5 classifications — including alpha-adrenergic agonists, stimulant drugs, serotonergic drugs. Lactobacillus Acidophilus has documented interactions with 1 drug class — the most serious being antibiotic drugs (moderate) — and none of Phenylephrine’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

Lactobacillus Acidophilus Does Interact With Other Medications

Lactobacillus Acidophilus has 182 moderate known drug interactions in our database — Phenylephrine 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. Phenylephrine)

Taking anything else?

Check Another of Your Medications Against Lactobacillus Acidophilus

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

What to actually watch for

No Interaction Found — But Data Suggests Lactobacillus Acidophilus and Phenylephrine 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.

Vomiting Additional detail
Lactobacillus Acidophilus
“Orally, taking Lactobacillus acidophilus in combination with other probiotics may cause gastrointestinal side effects including epigastric discomfort, abdominal pain, dyspepsia, flatulence, bloating, diarrhea, vomiting, and burping; however, these events are uncommon.”

Lactobacillus Acidophilus · Natural Medicines adverse-effect record, reported in diarrhea.
6 sources cited

90239. Chatterjee S, Kar P, Das T, Ray S, Gangulyt S, Rajendiran C, Mitra M. Randomised placebo-controlled double blind multicentric trial on efficacy and safety of Lactobacillus acidophilus LA-5 and Bifidobacterium BB-12 for prevention of antibiotic-associated

90291. Shavakhi A, Tabesh E, Yaghoutkar A, Hashemi H, Tabesh F, Khodadoostan M,Minakari M, Shavakhi S, Gholamrezaei A. The effects of multistrain probiotic compound on bismuth-containing quadruple therapy for Helicobacter pylori infection: a randomized placebo-c

111785. Sadrin S, Sennoune S, Gout B, et al. A 2-strain mixture of Lactobacillus acidophilus in the treatment of irritable bowel syndrome: A placebo-controlled randomized clinical trial. Dig Liver Dis 2020;52(5):534-540. PubMed

107497. Kumar S, Kumar R, Rohilla L, Jacob N, Yadav J, Sachdeva N. A high potency multi-strain probiotic improves glycemic control in children with new-onset type 1 diabetes mellitus: A randomized, double-blind, and placebo-controlled pilot study. Pediatr Diabete

107520. 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

107537. Xiao SD, Zhang DZ, Lu H, et al. Multicenter, randomized, controlled trial of heat-killed Lactobacillus acidophilus LB in patients with chronic diarrhea. Adv Ther. 2003;20(5):253-60.
Phenylephrine

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

Reported for Lactobacillus Acidophilus but not commonly for Phenylephrine: stomach upset, stomach pain, bloating or gas and a higher chance of infection.

Effects for Phenylephrine come from the ADVERSE REACTIONS section of its FDA label; effects for Lactobacillus Acidophilus come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 221,388 voluntary FDA FAERS reports for Phenylephrine that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Lactobacillus Acidophilus in Pregnancy & Breastfeeding

Pregnancy Possibly Safe

When used orally and appropriately. A combination of Lactobacillus acidophilus, Lacticaseibacillus casei, and Bifidobacterium bifidum has been used with apparent safety for 6 weeks, starting at 24-28 weeks' gestation.

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

Overlapping uses

What Phenylephrine Is Prescribed For, and What Lactobacillus Acidophilus Has Been Studied For

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

Phenylephrine is prescribed for: Phenylephrine is used in several different products, and each one has its own use. Injection (IV): raises blood pressure in adults with clinically important hypotension (low blood pressure) caused mainly by widened blood vessels. Some injections are labeled for anesthesia only. Others are labeled for anesthesia and septic shock.

Read the rest of what Phenylephrine is prescribed for

Eye drops: Phenylephrine Hydrochloride Ophthalmic Solution is used to dilate the pupil. Nasal products: temporarily relieve nasal and sinus congestion from the common cold, hay fever or other upper respiratory allergies. Rectal suppositories: relieve itching, burning and discomfort from hemorrhoids and temporarily shrink hemorrhoidal tissue.

Lactobacillus Acidophilus has been studied for:

Common cold studied, not established Lactobacillus Acidophilus has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

Lactobacillus Acidophilus for common cold

Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

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 Phenylephrine on your own; if you are taking Lactobacillus Acidophilus for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Lactobacillus Acidophilus or Phenylephrine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Lactobacillus Acidophilus or Phenylephrine, 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 Phenylephrine

This page covers Lactobacillus Acidophilus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phenylephrine page lists 81 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Ephedra (major), Lithium (major), Peyote (major) and Rauvolfia Vomitoria (major).

By severity: 6 major · 60 moderate · 15 minor.

From our pharmacist’s overview on the Phenylephrine page

“If you take phenylephrine (Sudafed PE, Biorphen) for congestion, treat this list as one that needs real attention, since six of its 81 entries carry a major rating. Phenylephrine tightens blood vessels to clear your nose, and more than half of the interactions here come from stimulant ingredients, ephedra above all, that can push blood…”

Reviewed by 2 · Jul 18, 2026

Open the Phenylephrine interaction page

One more smart check

Taking Lactobacillus Acidophilus as Part of a Dietary Supplement Product? Check It for Interactions

We hold 6,180 real supplement products containing Lactobacillus Acidophilus, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Lactobacillus Acidophilus. Even though Lactobacillus Acidophilus itself has no known interaction with Phenylephrine, 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 Lactobacillus Acidophilus and Phenylephrine 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 Lactobacillus Acidophilus

Top 5%

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

29 days ago today

Medication Phenylephrine

Top 25%

#668 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 Lactobacillus Acidophilus reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified October 4, 2026. The Lactobacillus Acidophilus and Phenylephrine records this page draws on were last updated July 11, 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 Lactobacillus Acidophilus

What is Lactobacillus Acidophilus?

Digestive health and balance
Diarrhea (including antibiotic-related)
Vaginal yeast and bacterial infections
Lactose intolerance
General immune support

Lactobacillus acidophilus is a 'friendly' bacterium used as a probiotic to support gut and vaginal health. It is generally well tolerated in healthy people, and there is reasonable evidence it may help with certain types of diarrhea, but proof for many other uses is limited. People with weakened immune systems or serious illness should check with a doctor before using it.

Lactobacillus acidophilus · Lactobacillaceae · Live bacterial cultures (the whole microorganism) · Capsules, tablets, chewables, powders, fermented foods (yogurt, kefir), and vaginal suppositories

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

Lactobacillus Acidophilus: dosing

There is no single official dose for L. acidophilus. Probiotic doses are usually measured in 'colony-forming units' (CFUs), and products vary widely in strength and strain.The best approach is to follow the directions on the product label, since these are based on the specific strain in that product. A pharmacist can help you choose a reputable product and a reasonable amount.Probiotics are often taken with or near a meal.

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

Read the full Lactobacillus Acidophilus monograph & all interactions

Medication

About Phenylephrine

What Is Phenylephrine Used For?

Brand names: Gilchew, AH Chew D, Gilchew IR, Sudafed PE, Biorphen

Phenylephrine is used in several different products, and each one has its own use.

Injection (IV): raises blood pressure in adults with clinically important hypotension (low blood pressure) caused mainly by widened blood vessels. Some injections are labeled for anesthesia only. Others are labeled for anesthesia and septic shock.

Eye drops: Phenylephrine Hydrochloride Ophthalmic Solution is used to dilate the pupil.

Nasal products: temporarily relieve nasal and sinus congestion from the common cold, hay fever or other upper respiratory allergies.

Rectal suppositories: relieve itching, burning and discomfort from hemorrhoids and temporarily shrink hemorrhoidal tissue.

Most-Reported Side Effects for Phenylephrine

From FAERS, the FDA’s public side-effect reporting system (221,388 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 20,609 reports

Headache 17,301 reports

Nausea 16,925 reports

Diarrhea 14,221 reports

Dyspnea 13,719 reports

See full Phenylephrine drug information

Keep checking

Other Drugs & Lactobacillus Acidophilus

Browse every other medication we’ve checked against Lactobacillus Acidophilus — 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 Lactobacillus Acidophilus page.

No interaction 2,647 drugs checked — show the list

We also checked Lactobacillus Acidophilus 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 Lactobacillus Acidophilus list.

See the full Lactobacillus Acidophilus interactions page

See every supplement checked against Phenylephrine, ranked by severity

Evidence & sources

Lactobacillus Acidophilus References

The 15 references that drive our Lactobacillus Acidophilus 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.

Pierce A. The American Pharmaceutical Association Practical Guide to Natural Medicines. New York: The Stonesong Press, 1999:19.
Begtrup LM, de Muckadell OB, Kjeldsen J, Christensen RD, Jarbøl DE. Long-term treatment with probiotics in primary care patients with irritable bowel syndrome--a randomised, double-blind, placebo controlled trial. Scand J Gastroenterol 2013;48(10):1127-35 PubMed
Chatterjee S, Kar P, Das T, Ray S, Gangulyt S, Rajendiran C, Mitra M. Randomised placebo-controlled double blind multicentric trial on efficacy and safety of Lactobacillus acidophilus LA-5 and Bifidobacterium BB-12 for prevention of antibiotic-associated
Shavakhi A, Tabesh E, Yaghoutkar A, Hashemi H, Tabesh F, Khodadoostan M,Minakari M, Shavakhi S, Gholamrezaei A. The effects of multistrain probiotic compound on bismuth-containing quadruple therapy for Helicobacter pylori infection: a randomized placebo-c
Karamali M, Dadkhah F, Sadrkhanlou M, et al. Effects of probiotic supplementation on glycaemic control and lipid profiles in gestational diabetes: a randomized, double-blind, placebo-controlled trial. Diabetes Metab 2016;42(4):234-41. PubMed
Badehnoosh B, Karamali M, Zarrati M, et al. The effects of probiotic supplementation on biomarkers of inflammation, oxidative stress and pregnancy outcomes in gestational diabetes. J Matern Fetal Neonatal Med. 2018 May;31(9):1128-1136.
Kumar S, Kumar R, Rohilla L, Jacob N, Yadav J, Sachdeva N. A high potency multi-strain probiotic improves glycemic control in children with new-onset type 1 diabetes mellitus: A randomized, double-blind, and placebo-controlled pilot study. Pediatr Diabete
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
Xiao SD, Zhang DZ, Lu H, et al. Multicenter, randomized, controlled trial of heat-killed Lactobacillus acidophilus LB in patients with chronic diarrhea. Adv Ther. 2003;20(5):253-60.
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
Ozer M, Goksu SY, Shahverdiani A, Mustafa M. Lactobacillus acidophilus-induced endocarditis and associated splenic abscess. Case Rep Infect Dis 2020;2020:1382709.
Sadrin S, Sennoune S, Gout B, et al. A 2-strain mixture of Lactobacillus acidophilus in the treatment of irritable bowel syndrome: A placebo-controlled randomized clinical trial. Dig Liver Dis 2020;52(5):534-540. PubMed
Stoffer JN, Slingsby TJ, Giuliari GP. Lactobacillus acidophilus endophthalmitis after intravitreal bevacizumab injection requiring intraocular lens explantation. Can J Ophthalmol 2022;57(1):e21-e22. PubMed
Cukovic-Cavka S, Likic R, Francetic I, Rustemovic N, Opacic M, Vucelic B. Lactobacillus acidophilus as a cause of liver abscess in a NOD2/CARD15-positive patient with Crohn's disease. Digestion 2006;73(2-3):107-10.
Hui J, Ren Y, Wang Y, Han Q. Lactobacillus acidophilus endophthalmitis postcataract operation: A case report with a literature review. Ocul Immunol Inflamm 2023.

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 Lactobacillus Acidophilus and Phenylephrine Together: Common Questions

Is it safe to take Lactobacillus Acidophilus with Phenylephrine?

We do not list a known interaction between Lactobacillus Acidophilus and Phenylephrine. 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 Lactobacillus Acidophilus and Phenylephrine 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.

Are Lactobacillus Acidophilus and Phenylephrine 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 Lactobacillus Acidophilus in each. That is a conversation for your prescriber, especially if Phenylephrine is being adjusted to a target.

How was the Lactobacillus Acidophilus and Phenylephrine combination checked?

Interactions in our licensed database are recorded against drug classes. Phenylephrine is filed under 5 classifications, and Lactobacillus Acidophilus has documented interactions with 1 drug class — none of Phenylephrine'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 Lactobacillus Acidophilus interact with any other medications?

Yes. Lactobacillus Acidophilus has 182 documented drug interactions in our database — Phenylephrine 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 Phenylephrine interact with any supplements?

Yes. Phenylephrine has documented interactions with 81 supplements in our database — Lactobacillus Acidophilus is not one of them. The Phenylephrine 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

Lactobacillus Acidophilus monograph Uses, safety profile, and every drug interaction in one place Phenylephrine drug information The full plain-English guide to this medication Phenylephrine supplement interactions Every supplement checked against Phenylephrine, 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 15 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Phenylephrine and Lactobacillus Acidophilus?

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.