Probiotics can help lower the chance of diarrhea caused by antibiotics, and the strains most often named are Saccharomyces boulardii, a yeast, and some Lactobacillus strains. In a 2020 meta-analysis of 36 placebo-controlled trials in adults, probiotics cut the rate of antibiotic-associated diarrhea by 38% compared with placebo. Which one, if any, fits you depends on your antibiotic, your health and how you take it, so bring that question to your prescriber or pharmacist.
Do engineered probiotics change what I should do?
Whether engineered probiotics work the same way in people is not known yet.
“Engineered” means the bacteria were changed in the lab. A review of probiotics and antibiotic side effects says natural gut microbes may be a potentially safer alternative to genetically modified strains, which it says may carry unforeseen risks. The same review says larger randomized human trials are still needed to establish the efficacy of specific probiotics in these settings.
So engineered probiotics are at an early stage. They don’t change the questions to ask about the probiotics available to you now.
Which probiotics help with antibiotic diarrhea, and which is best?
WebMD’s guide to probiotics for diarrhea says Saccharomyces boulardii and some strains of lactobacillus can work for diarrhea from antibiotics. The 2020 meta-analysis pooled 12 studies of Lactobacillus and found a lower risk of diarrhea (relative risk 0.67, 95% CI 0.50 to 0.91). It names Lactobacillus rhamnosus GG as the most studied Lactobacillus. It found no significant difference between single-species and multi-species products, and its authors say dosage, duration and strain-specific effects still need study before a specific recommendation can be made.
| Option | What the studies found | Who the study covered | Limits |
|---|---|---|---|
| Saccharomyces boulardii (yeast) | WebMD says it can work. In a meta-analysis cited by the 2020 review, it reduced diarrhea (relative risk 0.51, 95% CI 0.42 to 0.62) in people taking antibiotics for H. pylori treatment. | People on H. pylori eradication treatment in that analysis | WebMD calls the overall evidence for preventing C. difficile inconsistent. |
| Lactobacillus strains (12 studies pooled) | Relative risk 0.67 (95% CI 0.50 to 0.91) for diarrhea versus placebo. | Adults in the 2020 meta-analysis | Its authors call for more strain-specific study. |
| Bio-K+ capsule (L. acidophilus CL1285, L. paracasei LBC80R) | In a trial of 255 hospitalized adults aged 50 to 70, the review’s table reports it effectively reduced the risk of antibiotic-associated and C. difficile-associated diarrhea. | Hospitalized adults on penicillin, cephalosporin or clindamycin | One trial in a hospital population. |
| Lacidofil (L. helveticus R0052, L. rhamnosus R0011) | In 160 healthy adults taking one week of amoxicillin-clavulanic acid, the review’s table reports it reduced diarrhea duration. | Healthy adults aged 18 to 50 | Healthy participants, so it may not match people who are ill. |
| Yogurt drink (L. paracasei DN-114 001, S. thermophilus, L. bulgaricus) | In 135 hospitalized patients with a mean age of 74 who took one or more antibiotics, the review’s table reports fewer cases of antibiotic-associated and C. difficile-associated diarrhea. | Hospitalized older adults | A drink with named strains, not a general yogurt. |
| Yakult (L. paracasei Shirota) | The review’s table lists no observed beneficial effect on antibiotic-associated diarrhea in one trial. | Patients with antibiotic-associated diarrhea | Included for balance: products differ in results. |
Look at the strain name on any product before you decide. The probiotic labels explained guide shows how to read strain names and counts on a label.
Can you take too many probiotics?
In the 2020 meta-analysis, probiotic groups did not have a statistically significant increase in adverse events compared with placebo (relative risk 1.00, 95% CI 0.87 to 1.14). Its authors say the optimal dosage still needs study. If you wonder whether you are taking too much, ask your pharmacist before you change anything.
Can you take a probiotic and an antibiotic at the same time?
Yes, trials have done it. The 2020 meta-analysis notes that probiotics were used at the same time as antibiotics or were continued for 2 to 28 days after therapy. In its subgroup analyses, starting within the first two days of antibiotics was more beneficial for preventing diarrhea (relative risk 0.54) than starting later (relative risk 0.79). Matching the probiotic to the antibiotic course was more effective (relative risk 0.42) than continuing at least seven days after the course ended (relative risk 0.74). These are comparisons across different studies, not head-to-head trials.
Ask your pharmacist how your specific antibiotic and timing fit together.
Can I take a probiotic with Macrobid (nitrofurantoin) for a UTI?
The studies in this article are about diarrhea, not urinary tract infections, so they can’t tell you whether a probiotic pairs well with Macrobid. Ask the pharmacist who filled your prescription whether a probiotic fits your course, when to take it, and which strain, if any, to consider. If you develop diarrhea while on it, tell your prescriber.
Why don’t doctors tell you to take probiotics with antibiotics?
Firm guidance is still limited. A Washington University emergency medicine journal club page, titled for children, says that none of the included studies addressed parent or patient satisfaction, or time kept home from school, daycare or work. For that reason it says “it is difficult to make firm recommendation regarding probiotic use in children taking antibiotics,” and it suggests shared decision-making instead. Washington University’s journal club page on antibiotic diarrhea in children is the source of that point.
For adults, the 2020 meta-analysis reports that using probiotics as early as possible during antibiotic therapy has a positive and safe effect on preventing antibiotic-associated diarrhea. Its authors still call for studies on optimal dosage and duration before a specific recommendation. Your clinician can tell you whether that makes sense for you.
Which antibiotics are most linked to diarrhea?
In the 2020 meta-analysis, the type of antibiotic was the strongest predictor of antibiotic-associated diarrhea. Ampicillin or amoxicillin, cephalosporins and clindamycin, used alone, were most often associated with it, and other antibiotics used in combination also raised the risk. The review puts diarrhea at 5% to 39% of people on antibiotics and says it can persist for up to two months after treatment ends. It also notes that hospitalized patients face a higher risk than outpatients. If diarrhea lasts or becomes severe, tell a clinician.
How soon do probiotics work when you are on antibiotics?
The studies mostly measure whether diarrhea happens, not how fast a probiotic starts to help. What they do show is about timing at the start. The 2020 meta-analysis found starting within the first two days of antibiotics was more beneficial than starting later. WebMD says studies of children and adults show you may cut your chances of diarrhea if you take probiotics before and during treatment and for several days after stopping antibiotics.
What is the difference between antibiotics and probiotics?
Antibiotics are prescribed to kill the germs that cause an infection. WebMD notes they also kill some of the good bacteria in your intestines, which can upset the balance and cause diarrhea. Probiotics are the good bacteria, or yeast, added to your diet. The review quotes the standard definition of a probiotic as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.” For C. difficile infection, the review says probiotics “may help alleviate symptoms, they cannot eliminate the harmful effects.”
What do the studies on probiotics with antibiotics show?
News coverage of the question has framed it as more complicated than it looks: a 2018 CNN story, indexed on NCBI’s news page, says the answer “is more complicated.” The main studies are below.
| Study | What it found | Limit to know |
|---|---|---|
| 2020 meta-analysis of randomized placebo-controlled trials (36 trials, 9,312 adults) | Antibiotic-associated diarrhea was reduced by 38% (relative risk 0.62, 95% CI 0.51 to 0.74) compared with placebo. Adverse events were not significantly increased (relative risk 1.00). | Trials varied widely, and the authors restricted their findings to adults without immunodeficiency and without an intensive care unit history. |
| Hempel et al., JAMA, 2012, systematic review and meta-analysis | The pooled evidence associated probiotics with a reduction in antibiotic-associated diarrhea. | More research is needed to determine which probiotics give the greatest benefit. |
| Suez et al., Cell, 2018 | Its title reports that probiotics impaired post-antibiotic gut mucosal microbiome reconstitution, and that autologous fecal microbiota transplant improved it. | This is a title-level summary; read the full paper for its design. |
| Washington University emergency medicine journal club page, 2015 (titled for children) | Summarizes a Cochrane systematic review of 23 studies with 3,938 patients: fewer cases of antibiotic-associated diarrhea with probiotics, relative risk 0.46 (95% CI 0.35 to 0.61), with a number needed to treat of about 9. | The page says the clinical meaning of this is uncertain, and none of its included studies measured parent satisfaction or missed school or work. |
Are probiotics after antibiotics useful for kids?
The review says children typically have faster onset and shorter duration of antibiotic-associated diarrhea than adults. The Washington University page cites a reported incidence of around 5% in children. One trial in patients aged 3 months to 18 years, using Bifidobacterium bifidum W23 and Lactobacillus acidophilus W37 alongside broad-spectrum antibiotics, reported reduced risk of diarrhea during treatment and up to seven days after, according to the review’s table.
The Washington University page leaves the decision for children to shared decision-making, given the gaps in outcomes it describes. Talk with your child’s pediatrician before giving a probiotic with or after antibiotics.
Does food help, and when is diarrhea serious?
Harvard Health’s gut health guide describes fiber as food for the good bacteria that live in your gut. That is a description of how gut bacteria are fed, not a treatment for antibiotic diarrhea. WebMD says probiotics are found in certain foods, like yogurt, but the studies above tested named strains and drinks, so a regular yogurt is not the same as those products.
C. difficile is a different situation. WebMD says this infection causes severe and sometimes life-threatening diarrhea and inflammation in the colon. If your diarrhea is severe, have a clinician check it promptly.
Who should check with a clinician before using probiotics?
The adult meta-analysis covered adults without immunodeficiency and without an intensive care unit history. Its trials also excluded people who already had diarrhea at the start. The review adds that results appear to depend on age, nutritional status, diet, gut microbiota, pre-existing chronic diseases, frailty, place of residence and elderly care facilities. For general safety questions, read the probiotic supplement safety guide.
How do I check a probiotic’s label and claims?
As of October 2026, the FDA warning letter to Quten Research Institute from 2020 shows how the agency reads website claims. It cites claims that CoQ10 may help high blood pressure and that curcumin may help arthritis, and it says products intended for those uses are “new drugs” under section 201(p) of the Act (21 U.S.C. 321(p)), which need FDA approval before they are marketed. This is information, not legal advice. A product that promises to treat a condition is making a drug claim, so read claims closely.
WebMD’s guide to probiotics for diarrhea advises looking for a specific bacterium that has been tested, a Good Manufacturing Practices (GMP) seal, and wording that says the product still works “through end of shelf life” rather than “at time of manufacture.” Prices change and vary by store, so check today’s price directly with the maker or your pharmacy.
Before you decide: questions for your prescriber or pharmacist
- Is my antibiotic one linked to diarrhea, and does a probiotic make sense with it?
- If yes, which strain should I look for, and does the label name it?
- Does a probiotic fit my timing and any other medicines I take?
- What should I do if diarrhea is severe or doesn’t settle?
By SterlingMedicalCenter.org Editorial Team
This article is for general information purposes only and does not constitute medical advice. Consult your doctor or qualified healthcare provider before making changes to your health routine.
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