Does My Child Need Probiotics After Antibiotics?

By Bahee Van de Bor, RD, BCAPSc PGDipDiet, Specialist Paediatric Dietitian, former specialist dietitian at Great Ormond Street Hospital, with over 20 years of clinical experience in paediatric digestive health.

Does My Child Need Probiotics After Antibiotics?

You made it through the antibiotic course.

The infection cleared.

But now something else is off.

Maybe it’s loose stools that won’t settle.

Maybe your child’s tummy is bloated after meals.

Maybe they just seem uncomfortable in a way they weren’t before.

So you head to the pharmacy, find the probiotic shelf, and spend five minutes trying to work out which one to pick, because there are about fifteen of them and they all make similar promises on the front.

Before you put one in the basket, it is worth asking the question most parents skip:

Does my child actually need a probiotic at all?

The honest answer is: it depends on what you are trying to achieve.

And that changes everything about which product you choose, and whether you need one.

What antibiotics actually do to the gut

Antibiotics are brilliant at what they do.

They target the bacteria causing the infection and they work fast.

The problem is they cannot distinguish between the harmful bacteria and the beneficial ones.

Your child’s gut is home to trillions of bacteria working quietly to support digestion, immunity, and overall health.

When antibiotics come through, they knock out a significant portion of that ecosystem, the good alongside the bad.

For most children, the gut recovers naturally over time.

Some studies suggest the full diversity of gut bacteria can take considerably longer to return in young children than in adults, though the exact timeline varies.

This does not mean your child will feel unwell for months.

But it does explain why the tummy can feel unsettled for a while after the course ends.

Why do some children get antibiotic-associated diarrhoea and not others?

Not every child who takes antibiotics ends up with an upset tummy.

Up to a third of children taking antibiotics develop diarrhoea.

The majority do not.

The most likely explanation is that antibiotics disrupt the balance of bacteria in the gut, and some children’s guts react more to that disruption than others.

Several things increase the risk: the type of antibiotic (broad-spectrum antibiotics are harder on the gut), the length of the course, your child’s age, whether they need to be in hospital, and whether diarrhoea after antibiotics has happened before.

This is partly why the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) recommendation is framed around risk.

If your child has these risk factors, or if diarrhoea after antibiotics is a familiar pattern for them, that is when the evidence for a strain-specific probiotic is strongest.

If your child has taken antibiotics before with no gut symptoms, they may manage this course without one.

So does my child need a probiotic?

Here is where the evidence is more nuanced than the probiotic shelf would suggest.

We know that antibiotics alter the gut microbiome.

We know recovery happens.

What we do not yet know is the single best way to accelerate that recovery.

What the research is clear on is more specific:

• certain probiotic strains can significantly reduce the risk of antibiotic-associated diarrhoea in children.

That is a specific, targeted claim, and it is a well-supported one.

For a child who is already dealing with loose stools or tummy pain after antibiotics, it matters a lot.

It is also worth saying: most parents are not actually worried about their child’s microbiome.

They are worried about diarrhoea.

Or worried about tummy pain.

They want their child eating normally, sleeping properly, and back at school.

Those are the outcomes that matter, and they are the outcomes the evidence addresses.

So the question is not really “should I give a probiotic?”

It is: “Is diarrhoea or gut discomfort a problem right now, and if so, which probiotic actually has evidence in children?”

Not all probiotics are the same. The strain matters enormously.

This is the part most parents do not know, and it is why many feel like probiotics “don’t do much.”

A finding about one bacterial strain cannot be applied to a different strain, even if both are called “probiotics” and sitting next to each other on the same shelf.

A significant study from the Weizmann Institute found that giving generic multi-strain probiotic supplements to adults after antibiotics actually slowed down gut recovery.

Those who took nothing recovered faster.

The study was in adults, used unspecified multi-strain blends, and measured microbiome recovery rather than symptoms like diarrhoea.

That last point matters: it does not contradict the evidence for LGG and Saccharomyces boulardii, which are studied specifically for their effect on diarrhoea, not on microbiome diversity scores.

But it points to something important: a random mixture of bacterial strains is not the same as a targeted, evidence-based one.

The strains with actual clinical evidence in children are specific and named.

And they are not the ones in most supermarket probiotic bottles.

The two strains with the best evidence in children

Two specific strains carry a strong recommendation from the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN 2016, Szajewska et al.), confirmed by the Cochrane review in 2019.

Lactobacillus rhamnosus GG (LGG)

This is the most researched probiotic strain in paediatric medicine.

Multiple randomised controlled trials have tested it specifically in children.

In the trials reviewed by ESPGHAN, LGG reduced antibiotic-associated diarrhoea from 23% to 9.6%.

For every eight children treated, one case of diarrhoea is prevented.

The exact mechanism is not fully established, but the clinical evidence for its effect on diarrhoea is consistent and well-replicated across multiple trials.

Saccharomyces boulardii CNCM I-745

This one surprises parents.

It is a therapeutic yeast, not a bacterium.

That distinction matters here.

Because antibiotics only target bacteria, they do not affect Saccharomyces boulardii.

This means it can be started from day one of the antibiotic course without the antibiotic reducing its activity.

It has good clinical data for reducing diarrhoea in children.

The Cochrane and ESPGHAN reviews show it reduces antibiotic-associated diarrhoea from 20.9% to 8.8%.

That gives an NNT of 9, meaning for every nine children treated, one case of diarrhoea is prevented entirely.

Both strains have good evidence in children, although the evidence relates to each strain individually rather than to combination therapy.

For children who are more symptomatic, some clinicians use both, given that they work through different mechanisms.

That is a clinical decision rather than one with a direct evidence base, and it is worth discussing with your GP or paediatric dietitian.

One line worth remembering: the evidence for these strains is strain-specific and outcome-specific.

It applies to antibiotic-associated diarrhoea, in these named strains, at studied doses.

It cannot be extrapolated to other probiotic products, regardless of how they are marketed.

What to look for on the label

When choosing a product, look for the specific strain name, not just “probiotic” or “live cultures”, and check that the CFU count (colony-forming units) per strain is clearly disclosed.

I do not recommend products that hide behind a “proprietary blend” without stating exactly how many CFUs of each individual strain are inside.

If the label won’t tell you the dose per strain, you cannot know whether it will actually help.

That transparency is a minimum standard, not a bonus.

The dose matters as much as the strain.

The ESPGHAN position paper (Szajewska et al., J Pediatr Gastroenterol Nutr. 2016;62(3):495–506) sets out the doses the trials were built on.

For LGG: at least 10 billion CFUs daily.

For Saccharomyces boulardii CNCM I-745: 250–500 mg daily.

These are the doses that produced the NNT figures above.

Look for a product that states the strain name clearly on the label: Lactobacillus rhamnosus GG or LGG, or Saccharomyces boulardii CNCM I-745.

Check it also discloses the dose per strain.

Many children’s gummies and flavoured drops do not do this, which is often why parents find they do not seem to do very much.

A well-known example is Optibac Babies & Children, which contains LGG alongside two other strains, but only discloses a total of 3 billion CFUs across all three strains combined, with no per-strain breakdown.

Even if the entire 3 billion were LGG, that would still be a third of the therapeutic dose.

That is exactly why label transparency matters more than brand recognition.

How to give probiotics during and after antibiotics

During the course:

Start the probiotic on the same day as the antibiotics.

If you are using a bacterial probiotic (such as LGG), leave at least two hours between the antibiotic dose and the probiotic.

This reduces the chance of the antibiotic reducing its effectiveness before it reaches the gut.

If you are using Saccharomyces boulardii, the two-hour gap is not needed, as antibiotics do not affect yeast.

Should I give my child probiotics while on antibiotics?

Yes. Starting a strain-specific probiotic at the same time as antibiotics, rather than waiting until the course ends, gives the gut more protection during the period of disruption.

For bacterial strains like LGG, space the probiotic dose at least two hours away from the antibiotic.

For Saccharomyces boulardii, no spacing is required.

After the course ends:

This is where most parents stop too soon.

Continue the probiotic for two to four weeks after the antibiotic course has finished.

The post-course window is exactly when the gut is rebalancing and needs the most support.

What about yoghurt, kefir and fermented foods?

Yoghurt

One of the most common things parents tell me is: “I’ve been giving them yoghurt every day but their tummy is still upset.”

The yoghurt is usually the flavoured kind in tubes or pouches.

Standard supermarket yoghurts use culture strains grown for fermentation, not for any gut benefit, and many contain enough added sugar to draw water into the bowel and worsen loose stools.

If you are using yoghurt, plain and live is the version that counts.

Plain live yoghurt is fine if your child enjoys it and tolerates it.

Kefir

Kefir is promoted heavily as a microbiome food, but the trial evidence in children after antibiotics does not back the hype.

A paediatric RCT (Merenstein et al., 2009) found no significant reduction in antibiotic-associated diarrhoea (RR 0.83, not significant).

If your child likes kefir, you can include it in their diet as it is a source of protein, calcium and live microorganisms.

If they don’t, you are not missing anything essential.

Prebiotics from food

You do not need to force-feed sauerkraut, buy expensive fermented drinks, or remove entire food groups.

Unnecessary dietary restriction in children is not a neutral intervention.

Cutting out dairy removes calcium and iodine.

Cutting out wheat and gluten reduces fibre and prebiotic intake.

Most children do not need to do either.

For most children, the biggest contribution to recovery is simply returning to a varied, balanced diet once they are well enough to eat normally.

A variety of fibre-rich foods, from everyday sources like oats, bananas, vegetables, and pulses, supports the gut far better than any supplement.

Prebiotic supplements are not currently supported by sufficient evidence in children after antibiotics.

Food variety is the goal.

When the gut is not settling

For most children, a targeted probiotic continued for a few weeks after the course ends, alongside a return to normal eating, is enough.

The tummy settles.

Appetite returns.

Things go back to normal.

But some children do not follow that path.

If your child’s symptoms have not improved four to six weeks after finishing the antibiotic course, or if new symptoms have appeared since the course ended, that warrants a proper assessment.

If you see any of these, get medical advice promptly: unexplained weight loss, blood in the stools, persistent fever, significant vomiting, or diarrhoea that is not improving. These are alarm features under the Rome V criteria (Di Lorenzo et al., Gastroenterology 2026). They need proper evaluation, not a wait-and-see.

Beyond the red flags, some children develop an ongoing pattern after the illness:

• recurring tummy pain
• loose stools that never quite resolve
• significant bloating

These can settle into something more persistent.

It is also worth knowing that not every post-antibiotic problem is a post-antibiotic problem.

The sequence often looks like this: infection → antibiotics → infection clears → but gut symptoms continue.

Parents understandably blame the antibiotics.

But sometimes the trigger was the infection itself, not the medication.

Persistent abdominal pain and altered stool patterns following a gut infection can represent post-infectious IBS, a recognised condition in which the gut becomes hypersensitive long after the infection has cleared.

This matters because the approach is different.

The antibiotics were necessary.

The infection needed treating.

But if symptoms haven’t resolved, it is worth understanding what is actually driving them rather than continuing to try things and hope.

If that is where you are, the six patterns I see when a child’s gut does not settle after an infection sets out what each one looks like and what it needs.

Frequently Asked Questions