Antibiotics and LGG – A Powerful Team?

Antibiotics and LGG – A Powerful Team?

Antibiotics are an important group of medications. Most of us have had to use them at some point in our lives, and some of us have even been saved by them. Since the discovery of Penicillin this area of medicine has evolved to include hundreds of different antibiotics, and many serious infectious diseases that we once dreaded are now considered of minimal concern as they can be treated quickly and effectively.

But, to say that there is no downside at all to antibiotics would not be true. Whilst they target harmful bacteria in your body, they can also target beneficial bacteria, and so some of the ‘good guys’ get caught up in the crossfire. Not only this, but the human body is a balanced ecosystem, and so when bacteria are killed, even bad ones, then that balance shifts as some other bacteria grow with now decreased competition. The upshot is that whilst the course of antibiotics may kill off the infection that was causing problems, they have often killed off a great many beneficial microbes too, leading to side effects that have been known to last long after the course of antibiotics is done.

The side effects are rarely pleasant, the most common being loose stools, bloating both of the stomach and intestines, digestive discomfort, and in more serious cases diarrhoea. Nobody wants to experience any of these! But antibiotics have become very common medications in the modern world. In fact many would go so far as to describe them as essential medications. And so, as doctors have used these medicines more and more, there has been more research into how we might mitigate these side effects or even eliminate them altogether.

Researchers had an idea, what if we coupled antibiotics with probiotics? What if whilst killing off bacteria, we sent in more good bacteria at the same time to replace them and help reduce the side effects? That’s where Lactobacillus rhamnosus GG (LGG) comes in. It’s one of the few bacterial strains that has been extensively studied for how it behaves in the gut during antibiotic use. There have been a large number of double blind, randomised control trials into this area, and this type of trial is considered the gold standard in medical testing, so we know the results are valid. We’re excited about the results and what they suggest, and what this little microbe might do, so let us take you on a little journey to explore this promising field of research…

Ok, so what did these studies find?

The majority of the studies in this area focused on Antibiotic Associated Diarrhoea, or AAD, since this is one of the most serious side effects, and so it’s the one we want to stop first!

In a large number of high-quality human studies, groups taking LGG alongside antibiotics experienced a dramatic reduction in the number of people who developed diarrhoea compared with those taking a placebo, let’s have a look at a few of them.

In one major trial with 167 children, only around 5 % of those taking LGG experienced antibiotic-related diarrhoea, compared with 16 % in the placebo group, a very significant difference. Let’s break that down. That means that of the children just taking antibiotics, 16% got AAD, which means that without LGG the other children would most likely have had AAD at the same rate. But, that 16% was reduced down to just 5% when LGG was added, that’s a drop of almost 2/3rds in risk! 

Another study with over 200 children saw a similar pattern: 8 % vs 26 %, an even greater result than the last study, reinforcing the evidence that LGG appeared to have really helped reduce the incidence of AAD in these children.

A large meta-analysis reviewing data from more than 1500 participants found the same trend. These are studies that take the results of a group of other studies that all looked at similar things in a similar way, and then added them all together to see what the average results were across a larger group of people. Of course, the studies they use had to be of a high clinical standard, so as to ensure that they were all a fair test, if they were to be included. The results were consistent across the board, those taking LGG had about two-thirds lower risk of antibiotic-associated diarrhoea overall on average. AAD is unpleasant to say the least, but a decrease of 2/3rds is a massive drop in risk, a very promising result for this powerful microbe.

The effectiveness didn’t just stop at reducing the rate though. You may be asking: ok, so only 5% on LGG got AAD, but what about that 5%? How did they fare?

Well, the results show that in the people that still got AAD anyway, their symptoms were shorter lived. The control group on average suffered for a total of 4 or more days on average, which is a long time to have to deal with something as unpleasant as this. The LGG group on the other hand only had to put up with it for 2 days on average, a spectacular 50% drop in the duration of this nasty side effect!

So not only did LGG appear to help prevent AAD in the first place, but when it did happen, it lasted for half as long, showing that weather the patients got AAD or not, there was a benefit either way. Not bad going for this microbe!

Ok, so how does this apply to me then?

We’ve all had to take antibiotics at some point. Sometimes your body has to deal with an infection that is just too much, and antibiotics can step in to help. But for anyone who has had to take a course of very strong antibiotics, or an intensive course to really hit an infection hard, you’ll know, side effects can be unpleasant! It’s only natural that we would want to find some way to reduce them.

The research suggests that LGG helps to stabilise the natural bacterial balance in the gut while it’s under stress. By keeping this environment more balanced and populated with beneficial bacteria, participants reported fewer bouts of loose stools, and less bloating, flatulence, and general digestive upset during antibiotic therapy. In one adult trial, people taking LGG alongside a common antibiotic course described a calmer, more comfortable digestion, and many found it easier to complete their medication without side-effects getting in the way.

This is important. It doesn’t just mean that the positive effects of LGG were just numbers on paper. It actually translated into real effects that the participants of this study could actually feel, making their treatment that much more manageable for them.

But it’s not just us that think this way, some major international medical bodies have recognised the benefits here and actually recommend probiotics alongside antibiotics as a result of studies like these! The Royal Australian College of General Practitioners includes probiotics as an option in their guidance for GPs. Both the ESPGHAN and the BSPGHAN (European/British Society for Paediatric Gastroenterology, Hepatology and Nutrition) recommend LGG specifically alongside antibiotics for children, with the Europeans recommending it by name, and the British citing the European article as a clinical resource. And the British Dietetic Association has openly acknowledged that there is evidence that certain probiotics can help mitigate AAD, both during treatment and afterwards. This is a big deal as not only has the research shown results, but those results have been adopted by major medical bodies.

So, the next time you need to take a course of antibiotics, think about how they might impact your gut flora, and ask your doctor about the possibility of taking probiotics like LGG alongside them, they might just make your treatment that bit more comfortable.  

References (the science) – Don’t just take our word for it:

1. Guandalini, S., Pensabene, L., Zikri, M.A., et al. (2000) Lactobacillus GG administered in oral rehydration solution to children with acute diarrhea: a multicenter European trial. Journal of Pediatric Gastroenterology and Nutrition, 30(1), 54–60. https://pubmed.ncbi.nlm.nih.gov/10630441
2. Szajewska, H. & Kolodziej, M. (2015) Systematic review with meta-analysis: Lactobacillus rhamnosus GG in the prevention of antibiotic-associated diarrhoea in children and adults. Alimentary Pharmacology & Therapeutics, 42(10), 1149–1157. https://pubmed.ncbi.nlm.nih.gov/26365388
3. Vanderhoof, J.A., Whitney, D.B., Antonson, D.L., et al. (1999) Lactobacillus GG in the prevention of antibiotic-associated diarrhoea in children. Journal of Pediatrics, 135(5), 564–568. https://pubmed.ncbi.nlm.nih.gov/10547242
4. Arvola, T., Laiho, K., Torkkeli, S., et al. (1999) Prophylactic Lactobacillus GG reduces antibiotic-associated diarrhoea in children with respiratory infections: a randomized study. Pediatrics, 104(5), e64. https://pubmed.ncbi.nlm.nih.gov/10545585
5. Royal Australian College of General Practitioners (RACGP) (n.d.) Probiotics for the prevention of antibiotic-associated diarrhoea in adults and children. HANDI (Handbook of Non-Drug Interventions). Available at: https://www.racgp.org.au/clinical-resources/clinical-guidelines/handi/handi-interventions/nutrition/probiotics-for-the-prevention-of-antibiotic (Accessed: 16 January 2026).
6. Szajewska, H. et al. (2016) ‘Probiotics for the prevention of antibiotic-associated diarrhea in children’, Journal of Pediatric Gastroenterology and Nutrition, 62(3), pp. 495–506. (ESPGHAN Working Group on Probiotics and Prebiotics position paper PDF). Available at: https://www.espghan.org/dam/jcr:bb0de387-55d2-49bd-bb02-40d31b5e7c1e/2016_Probiotics_for_the_Prevention_of_Antibiotic-Associated_Diarrhea_in_Children.pdf (Accessed: 16 January 2026).
7. Szajewska, H. et al. (2023) ‘Probiotics for the management of pediatric gastrointestinal disorders’, Journal of Pediatric Gastroenterology and Nutrition, 76(2), pp. 235–256. (Hosted on BSPGHAN website). Available at: https://bspghan.org.uk/wp-content/uploads/2023/03/probiotics-for-the-management-of-pediatric.pdf (Accessed: 16 January 2026).
8. British Dietetic Association (BDA) (2022) Probiotics and gut health (Food Factsheet). Available at: https://www.bda.uk.com/resource/probiotics.html (Accessed: 16 January 2026).