How to take a probiotic with antibiotics, step by step

Antibiotics and probiotics get mentioned together so often that it can seem like one automatically comes with the other. The research is more nuanced than that.

It does offer useful guidance, though, about who is most likely to benefit, which products were studied and when to start. Here's how to approach it, step by step.

Step 1: Know what the research found

Antibiotics don't only hit the bacteria causing an infection. They can also disturb the microbes that normally live in your gut (Goldenberg et al., 2017), and diarrhea is a common side effect (Hempel et al., 2012). Two large reviews looked at whether probiotics change that:

• Antibiotic-associated diarrhea. A meta-analysis pooled 63 randomized trials with 11,811 participants. Taking probiotics was associated with a lower risk of antibiotic-associated diarrhea (relative risk 0.58). On average, 13 people needed to take a probiotic for one fewer person to develop diarrhea. The authors noted that strains were often poorly documented and that results varied considerably between studies (Hempel et al., 2012).
• C. difficile-associated diarrhea. A Cochrane review of 31 trials with 8,672 patients found this more serious type of diarrhea in 1.5% of people taking probiotics, compared with 4.0% of people in control groups. The benefit was concentrated in trials where the baseline risk was above 5%. In trials with a lower baseline risk, there was no clear difference (Goldenberg et al., 2017).

So the size of the potential benefit depends heavily on your own risk. If you're a generally healthy adult taking a short course at home, ask your doctor what your risk looks like, because that's where the evidence shows the biggest differences.

Step 2: Check whether a probiotic is right for you

The Cochrane authors concluded that short-term probiotic use alongside antibiotics appears safe for people who are not immunocompromised or severely debilitated (Goldenberg et al., 2017). That qualifier matters.

If you have a weakened immune system, are seriously ill, are recovering from major surgery or have a central line, talk to your doctor before adding any probiotic.

A few questions worth asking when you pick up the prescription:

• Is my risk of antibiotic-related diarrhea or C. difficile higher than average with this antibiotic, or because of my health history?
• Is there a specific probiotic strain you'd suggest, or one I should avoid with my other medications?
• How should I time it around my antibiotic doses?
• How long should I keep taking it after the antibiotic course ends?

Step 3: Choose a product that was studied for this

Not every probiotic has been tested alongside antibiotics, and results differ by product. In its 2020 technical review, the American Gastroenterological Association described the overall evidence on probiotics and C. difficile-associated diarrhea as promising, especially for certain strains and combinations. The yeast Saccharomyces boulardii was the only single-strain probiotic with a significant effect, and the panel noted that antibiotics typically don't kill yeast. It rated the overall certainty of the evidence as low (Preidis et al., 2020).

Whatever you consider, look for full strain names so you can match the product to the research. A pharmacist can help you compare options.

Step 4: Start early

Timing seems to matter. A meta-analysis of 19 studies with 6,261 hospitalized adults found probiotics were more effective the closer they were started to the first antibiotic dose, with less benefit for every day of delay. Starting within 2 days was linked to a larger drop in C. difficile infection (relative risk 0.32) than starting later (relative risk 0.70, which was not statistically significant) (Shen et al., 2017).

In practice, if you and your doctor decide a probiotic makes sense, that points to starting on the first or second day of the antibiotic course rather than waiting until the end.

Step 5: Space the doses and follow the label

A common suggestion on bacterial probiotic labels is to take them a couple of hours apart from the antibiotic, since the antibiotic might kill some of the probiotic bacteria. That's a sensible precaution, but it hasn't been well studied. The AGA review noted that most trials didn't describe whether the probiotic was chosen based on its ability to survive the specific antibiotic being used (Preidis et al., 2020).

Here's what that can look like for an antibiotic taken twice a day, if your pharmacist agrees:

• 8 a.m.: antibiotic dose with breakfast, or as directed
• Around noon: bacterial probiotic with lunch
• 8 p.m.: second antibiotic dose

Keep taking the antibiotic exactly as prescribed. A probiotic is an add-on, never a reason to shorten or skip doses. If you notice new symptoms, write down when they started, what you took and when, so you can give your doctor a clear picture.

Step 6: Know the open question about recovery

One detailed study complicates the picture. Researchers gave antibiotics to mice and to human volunteers, followed by a multi-strain probiotic, a transplant of the person's own previously stored gut bacteria, or nothing. Compared with natural recovery, the probiotic markedly delayed the return of the original gut bacteria, and recovery stayed incomplete. The transplant of a person's own bacteria led to a rapid, near-complete recovery within days (Suez et al., 2018).

What this means for symptoms isn't clear, since the study measured gut bacteria rather than diarrhea. But it's a good reason not to think of a probiotic as an automatic "reset" after antibiotics, and to ask your doctor how long it makes sense to keep taking one.

Step 7: Watch for signs that need a doctor

Call your doctor during or after a course of antibiotics if you have:

• Frequent watery diarrhea that doesn't settle within a day or two
• Blood or mucus in your stool
• Fever, or abdominal pain or cramping that's getting worse
• Signs of dehydration, such as dizziness, a dry mouth or very little urine
• Diarrhea that starts days or weeks after you've finished the antibiotics

These can be signs of C. difficile infection or another problem that needs medical care, not a supplement.

Sources

1. Goldenberg JZ, Yap C, Lytvyn L, et al. Probiotics for the prevention of Clostridium difficile-associated diarrhea in adults and children. Cochrane Database Syst Rev. 2017;12(12):CD006095. PMID 29257353
2. Hempel S, Newberry SJ, Maher AR, et al. Probiotics for the prevention and treatment of antibiotic-associated diarrhea: a systematic review and meta-analysis. JAMA. 2012;307(18):1959-69. PMID 22570464
3. Preidis GA, Weizman AV, Kashyap PC, Morgan RL. AGA technical review on the role of probiotics in the management of gastrointestinal disorders. Gastroenterology. 2020;159(2):708-738.e4. PMID 32531292
4. Shen NT, Maw A, Tmanova LL, et al. Timely use of probiotics in hospitalized adults prevents Clostridium difficile infection: a systematic review with meta-regression analysis. Gastroenterology. 2017;152(8):1889-1900.e9. PMID 28192108
5. Suez J, Zmora N, Zilberman-Schapira G, et al. Post-antibiotic gut mucosal microbiome reconstitution is impaired by probiotics and improved by autologous FMT. Cell. 2018;174(6):1406-1423.e16. PMID 30193113

This article is for general information and isn't medical advice. Always take antibiotics exactly as prescribed, and ask your doctor or pharmacist before adding a probiotic, especially if you're immunocompromised, seriously ill or take other prescription medication.