Probiotics With Antibiotics: Which Ones, When, and Does 50 Billion CFU Matter?

Short answer: the probiotics with the most evidence for use alongside antibiotics are Lactobacillus rhamnosus GG (LGG) and the yeast Saccharomyces boulardii. Studies that found a benefit generally started them within 2 days of the first antibiotic dose. A higher CFU count doesn't automatically mean a better product, and the benefit seen in adults 18–64 wasn't found in adults over 65. Details and sources below.

This article is general information, not medical advice. Ask your doctor or pharmacist before taking a probiotic with an antibiotic — especially if you are seriously ill, immunocompromised, or caring for an infant or older adult.

Why do people take probiotics with antibiotics?

Antibiotics can disrupt the normal bacteria in your gut, and some people develop antibiotic-associated diarrhea (AAD). According to the NIH Office of Dietary Supplements, up to 30% of patients who use antibiotics experience AAD, and the risk is higher for people in hospital, children under 2 and adults over 65 (NIH ODS, Probiotics fact sheet).

What are the best probiotics to take with antibiotics?

The two with the strongest published evidence are LGG and Saccharomyces boulardii. Benefits are strain-specific, so look for the exact strain on the label — "Lactobacillus" alone isn't enough to know.

• LGG: a meta-analysis of 12 randomized trials (1,499 children and adults) found LGG lowered the risk of AAD from 22.4% to 12.3%; when children and adults were analyzed separately, the difference was only statistically significant in children (Szajewska & Kołodziej, 2015).
• S. boulardii: a meta-analysis of 21 randomized trials (4,780 participants) found it lowered the risk of AAD in adults from 17.4% to 8.2%, and in children from 20.9% to 8.8%, with no clear dose effect (Szajewska & Kołodziej, 2015).

Because S. boulardii is a yeast, antibiotics don't kill it — one reason it's often discussed for use during an antibiotic course.

When should you start a probiotic during antibiotics?

The NIH fact sheet summarizes the evidence this way: starting LGG or S. boulardii within 2 days of the first antibiotic dose helps reduce the risk of AAD in children and adults age 18 to 64 (NIH ODS). How far apart to space the two doses each day depends on the product and the antibiotic — ask your pharmacist, who can see your exact prescription.

Is a 50 billion CFU probiotic better than 10 or 20 billion?

Not necessarily. CFU (colony-forming units) is the number of live microbes per dose. Many supplements contain 1 to 10 billion CFU and some 50 billion or more, but the NIH notes that products with higher CFU counts are not necessarily more effective than products with a lower count (NIH ODS). The strain, and whether it was studied for your situation, matters more than the headline number.

One label detail does matter: probiotics can die during storage, so look for the CFU count guaranteed through the expiration date, not "at time of manufacture."

Do probiotics need to be refrigerated?

It depends on the product. Some require refrigeration and others are made to be stored at room temperature — the NIH fact sheet, citing the World Gastroenterology Organisation, advises checking the label for storage conditions. A refrigerated probiotic isn't automatically better; what counts is that it's stored the way its label says, so the CFU count holds up to the expiration date.

Should men (or women) over 70 take probiotics with antibiotics?

The evidence is weaker after 65. A meta-analysis found probiotics reduced the risk of AAD in adults 18–64 but not in adults over 65 (Jafarnejad et al., 2016). That doesn't mean they never help an older person, but it's a good reason to ask the prescriber rather than assume.

Safety also matters more with age and illness: probiotics have been linked to rare but serious bloodstream infections, mostly in people who were severely ill or immunocompromised (NIH ODS). Anyone in that group should only take a probiotic on medical advice.

What about everyday probiotics when you're not on antibiotics?

The NIH puts it plainly: expert bodies of health professionals make no recommendations for or against the use of probiotics by healthy people, and not every product labeled "probiotic" has proven benefits. If you take one for general digestive comfort, choose a product that names its strains and guarantees its CFU through expiration — and treat it as one part of a diet rich in fiber, fruits and vegetables, not a replacement for one.

Where does Juice Plus+ fit?

Juice Plus+ makes a daily probiotic, but it is not marketed for use with antibiotics, and its product description doesn't name LGG or S. boulardii. So if your goal is specifically the antibiotic situation above, look for one of the studied strains and ask your pharmacist.

For everyday digestive support, the official product descriptions say:

• Juice Plus+ Probiotic Capsules — one capsule a day with 20 billion CFU from 9 bacteria species (Lactobacillus and Bifidobacterium), to "replenish good bacteria and promote microbial diversity to support digestive health, including occasional bloating."*
• Juice Plus+ Prebiotic Powder — one stick in water, a blend of six plant-based prebiotic fibers with 4 g of dietary fiber to feed good bacteria.*
• Probiotic Capsules + Prebiotic Powder — the two together as a daily routine.*

Check the product label for the full strain list, storage instructions and how CFU is stated. *These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Frequently asked questions

Can I take a probiotic at the same time as my antibiotic?

Studies that found a benefit started the probiotic within 2 days of the first antibiotic dose. Ask your pharmacist how to space the doses for your specific antibiotic and probiotic.

Which probiotic strain has the most evidence for antibiotic-associated diarrhea?

Lactobacillus rhamnosus GG and Saccharomyces boulardii, according to meta-analyses summarized by the NIH Office of Dietary Supplements.

Is 50 billion CFU better than 20 billion?

Not necessarily — higher CFU counts aren't automatically more effective. The strain and a CFU count guaranteed through the expiration date matter more.

Are refrigerated probiotics better than shelf-stable ones?

No — both can work. Store each product the way its label says.

Do probiotics help older adults on antibiotics?

A meta-analysis found a benefit for adults 18–64 but not for those over 65. Older adults, and anyone seriously ill or immunocompromised, should ask their doctor first.

Sources

• NIH Office of Dietary Supplements. Probiotics — Fact Sheet for Health Professionals (updated March 25, 2025).
• Szajewska H, Kołodziej M. Lactobacillus rhamnosus GG in the prevention of antibiotic-associated diarrhoea in children and adults. Aliment Pharmacol Ther, 2015.
• Szajewska H, Kołodziej M. Saccharomyces boulardii in the prevention of antibiotic-associated diarrhoea. Aliment Pharmacol Ther, 2015.
• Jafarnejad S, et al. Probiotics Reduce the Risk of Antibiotic-Associated Diarrhea in Adults (18-64 Years) but Not the Elderly (>65 Years). Nutr Clin Pract, 2016.