5 Possible Side Effects of Probiotics

Author's Bio: Ashley Oswald, RDN, IFNCP, CLT, LD

If you started taking a probiotic because you wanted better digestion… but suddenly you're more bloated, gassy, having diarrhea, or just feeling worse, you might be wondering:

Is this normal? Or is my probiotic actually making things worse?

And this is where probiotics can get confusing.

Because probiotics can be helpful for gut health, especially if you are taking a strain that has research showing it to be helpful for the issue you are struggling with, but that does not mean every probiotic is right for every person.

There are actually several side effects of probiotics that can happen when you start taking one.

Some may simply mean your gut needs a little time to adjust…

But others can be a clue that the particular probiotic you're taking isn't a good fit for what is actually happening inside your gut.

So today, we're going through five possible probiotic side effects I want you to know about.

And stay with me, because toward the end I'm going to explain what you can actually do if probiotics seem to make you feel worse, including a couple of options that most people don't even realize exist.

We'll also talk about how to choose a probiotic in the first place, because with all the options out there, it's very easy to spend a lot of money on something that may not actually be right for you.

Hi everyone, I'm Ashley Oswald, a Harvard trained gut health dietitian and founder of Oswald Digestive Clinic.

At our clinic, we work with people who are dealing with things like gas, bloating, diarrhea, constipation, food intolerances, and other digestive symptoms, especially when they've tried a bunch of things on their own and still don't really understand why they're having symptoms.

And probiotics are actually a perfect example of this.

Because sometimes they help.

Sometimes they make absolutely no difference.

And sometimes they make someone feel significantly worse.

So let's talk about why.

https://youtu.be/4FZQsSjrbQw

[Video Transcript Below Video - it is the same information]

What Are Probiotics Actually Doing?

Probiotics are beneficial bacteria or yeasts that can support both gut health and immune function.

One of the ways they do this is by competing with potentially harmful microorganisms inside the gut.

I like to think about your microbiome almost like a garden.

You have the plants you actually want growing in the garden…

and then you have weeds.

Your beneficial microorganisms are like the plants you're trying to grow.

The potentially harmful organisms are the weeds.

And if those weeds start completely taking over, your garden isn't going to function very well.

Probiotics can help create an environment that's less favorable for some of those unwanted microorganisms.

Certain beneficial microbes can even produce compounds that inhibit pathogens.

Pretty interesting.

But that's not all they're doing.

Probiotics may also support the intestinal barrier, and the microorganisms living in our gut are involved in processes related to neurotransmitters such as GABA and serotonin.

That's one reason there's been so much interest in the connection between gut health, the brain, stress, mood, immune function, and overall health.

But here's something I think a lot of people misunderstand.

The probiotic you swallow doesn't necessarily move into your gut, unpack its bags, and live there forever.

Depending on the strain and your individual gut environment, many probiotic organisms only remain temporarily.

Often somewhere around one to three weeks.

So consistency can matter, whether you're getting beneficial microorganisms from supplements or fermented foods.

But the bigger point here is that probiotics are interacting with an ecosystem that's already there.

And everybody's ecosystem is different.

That's one reason two people can take the exact same probiotic and have completely different experiences.

One person says, "This changed my life."

Another person says, "This made me so bloated I couldn't button my pants."

And neither person is necessarily wrong.

So Who Might Benefit From Probiotics?

Many people use probiotics for general digestive or immune support.

But probiotics have also been studied in connection with a number of specific conditions, including things like antibiotic-associated diarrhea, IBS, Crohn's disease, ulcerative colitis, diverticular disease, eczema, urinary tract infections, the common cold, rheumatoid arthritis, and even oral health.

That does not mean everybody with one of those conditions should automatically take the same probiotic.

The specific organism matters.

The dose matters.

And most importantly, the person matters.

This is something we see quite a bit at Oswald Digestive Clinic.

Someone comes in and they've already tried three, four, five different gut supplements because somebody online said they were "good for gut health."

But nobody ever stopped to ask:

What is actually causing this person's symptoms in the first place?

That's the piece that can get missed.

Because if your bloating, diarrhea, or constipation has an underlying cause not related to the microbiome, then randomly adding probiotic supplements likely won’t solve these bothersome symptoms.

Further I must add that people who are severely immunocompromised, critically ill, have certain serious medical conditions such as pancreatitis, or have a central venous catheter may need to avoid probiotics or use them only under medical supervision.

Now let's get into the side effects.

And number one is probably the one I hear about most often.

Side Effect #1: Gas and Bloating

If you start taking a probiotic and suddenly you're more bloated…

you're not imagining it.

This can happen.

These microorganisms interact with material inside your digestive tract, and that process can result in fermentation and gas production.

So when you suddenly introduce new or additional microorganisms, your digestive system may need a little time to adjust.

For some people, mild bloating or gas at the beginning settles down after a short adjustment period.

But here's where I want you to be careful.

Don't automatically assume that every case of bloating means, "The probiotic is working."

That's something I hear a lot.

"Well, I feel horrible, so I guess it's killing off all the bad bacteria."

Not necessarily.

If the bloating is significant or continues, it can sometimes be a sign that there's something else happening with digestion or with the overall balance of your gut microbiome.

And that's when we really want to look at the bigger picture.

For example, at our clinic, if someone comes to us with chronic bloating, we're not just asking what probiotic they're taking.

We're looking at their symptoms as a whole.

When does the bloating happen?

What foods trigger it?

Are they constipated?

Do they have diarrhea?

Are there signs they're not digesting certain foods well?

Because the goal isn't to find a supplement that covers up the symptom.

The goal is to understand why the symptom is happening.

And there's one more really important thing to check if your probiotic makes you bloated.

Look at the other ingredients on the label.

A lot of probiotic supplements also contain prebiotic fibers.

Ingredients such as inulin and certain oligosaccharides are highly fermentable.

And some people are very sensitive to them.

So you could be blaming the probiotic bacteria…

when the actual problem is one of the additional ingredients.

That's why looking at the entire label is so important.

Now let's move on to number two.

Because bloating is uncomfortable…

but what if the probiotic starts causing actual abdominal pain?

Side Effect #2: Abdominal Discomfort or Pain

Abdominal discomfort or pain can occur in some people taking probiotics.

And this has actually shown up in the research.

A 2019 meta-analysis looked at nine randomized controlled trials involving 826 patients with inflammatory bowel disease.

In that analysis, the risk of developing abdominal pain was reported to be about 2.59 times higher in those taking probiotics compared with placebo.

Now, abdominal pain can obviously have a lot of different causes.

So if you're experiencing significant or persistent abdominal pain, I wouldn't simply assume, "Oh, it's just my probiotic," and ignore it.

That's a symptom that may need to be evaluated.

But if you notice a very clear pattern where you start a new probiotic…

and shortly afterward you start having new abdominal discomfort…

pay attention to that connection.

Your body is giving you information.

And later in this video, we'll talk about ways you can adjust your probiotic rather than immediately deciding that probiotics as a whole aren't for you.

But first, we have one that sounds almost backwards.

Side Effect #3: Diarrhea

Yes.

A supplement people often take to improve diarrhea can sometimes cause diarrhea.

Probiotics have been studied for situations like infectious diarrhea, C. difficile-associated diarrhea, and antibiotic-associated diarrhea.

But some people can still develop looser stools when they first introduce one.

Think of adding probiotics to your gut almost like inviting a bunch of new people to a party.

There's already a whole group of people there.

Then suddenly these newcomers walk in.

Sometimes everybody gets along beautifully.

And sometimes there's a little chaos before things settle down.

Your gut microbiome is an incredibly complex ecosystem.

So introducing a new organism can temporarily change what's happening inside it.

If you develop mild diarrhea shortly after starting a probiotic, you may choose to give your digestive system a little time to adjust.

And definitely make sure you're staying adequately hydrated.

But if diarrhea continues for a week or two, gets worse, or is accompanied by other concerning symptoms, don't just keep taking the supplement indefinitely because somebody told you probiotics are good for you.

This is another thing we see with clients.

They'll say,

"I've been taking this for three months and I've had diarrhea the entire time, but I thought I needed to push through."

No.

At some point, we need to reevaluate what you're doing.

Sometimes the answer is a lower dose.

Sometimes it's a different organism.

And sometimes that probiotic simply isn't appropriate for you.

We're going to talk about some alternatives in a minute.

But before that, let's talk about a side effect people often don't associate with their probiotic at all.

Side Effect #4: Allergic Reactions

When you pick up a probiotic bottle, you're probably focused on the bacteria listed on the front.

But the bacteria aren't necessarily the only thing inside that supplement.

Some probiotic products can contain, or potentially be exposed to, common allergens including dairy, egg, soy, gluten, or yeast.

A Spanish study published in 2012 investigated 11 different probiotic products.

Researchers detected cow's milk proteins in 10 of them and egg white proteins in three.

But only eight of those products warned about milk…

and none warned about egg.

That's pretty surprising.

Gluten can also potentially be an issue because microorganisms used during probiotic manufacturing may be grown using media that contains gluten-derived ingredients.

So if you have a diagnosed food allergy, don't assume a probiotic is automatically safe simply because you wouldn't expect your allergen to be there.

Research the specific product.

And when necessary, reach out directly to the manufacturer.

This is also why quality matters so much with supplements.

And we'll come back to that near the end.

But now we get to number five.

And this is where the specific strain of probiotic can become particularly important.

Side Effect #5: Histamine Issues

Probiotics can be complicated for people who are sensitive to histamine.

Histamine is a chemical messenger released by mast cells as part of our immune response.

And histamine isn't inherently bad.

We actually need it.

The issue happens when someone produces or accumulates more histamine than their body is able to effectively break down.

This is sometimes referred to as histamine intolerance.

Symptoms associated with histamine issues can include headaches, dizziness, skin flushing, nasal congestion, and other reactions.

So what in the world does that have to do with your probiotic?

Well, different bacteria may affect histamine differently.

Certain bacterial species have been associated with increasing histamine production.

Examples include strains within species such as Lactobacillus casei and Lactobacillus bulgaricus.

Other bacteria, including strains of Lactobacillus rhamnosus and Bifidobacterium infantis, have been studied for potentially different effects.

And this is where grabbing any random probiotic off the shelf can get tricky.

Two products can both say "probiotic" on the front…

but contain completely different organisms.

So if you're somebody who seems to react very easily to fermented foods, or other foods associated with histamine such as aged foods or leftovers, I would pay particular attention to exactly which strains you're taking.

And again, there may also be other ingredients in the supplement that are contributing to the reaction.

Okay.

Now here's what I really want you to know.

Having a reaction to one probiotic does not necessarily mean probiotics are completely off the table for you forever.

Sometimes a small change can make a surprisingly big difference.

What Can You Do If Probiotics Make You Feel Worse?

The first thing you could experiment with is changing when you take your probiotic.

If you've been taking it first thing in the morning and then spending the rest of the day uncomfortable and bloated, you might try taking it later in the day or in the evening.

The gut tends to be less active while we're sleeping, and there's generally less food moving through the digestive system for those microorganisms to interact with.

And practically speaking…

if you're going to have a little temporary bloating, you'd probably rather sleep through some of it than deal with it while you're sitting at work or trying to go about your day.

But if even a small amount of live probiotic seems to bother you, there's another option most people have never heard of.

Have You Ever Heard of a "Dead" Probiotic?

It sounds completely backwards.

Because if probiotics are beneficial bacteria, shouldn't they have to be alive?

Not necessarily.

Research suggests that even inactivated microorganisms may retain certain beneficial properties.

A randomized controlled trial published in 2020 looked at heat-inactivated Bifidobacterium in people with IBS and compared it with placebo.

The group receiving the heat-inactivated bacteria experienced significant improvement in IBS symptoms.

So even though those organisms weren't alive, components of the microorganisms could still interact with the body in potentially beneficial ways.

You may hear these referred to as heat-killed probiotics or, depending on the product and context, post-biotics.

For someone who doesn't tolerate traditional live cultures well, that's something worth knowing exists.

You May Need to Break Up With Your Current Probiotic

And then there's another possibility.

You may simply need to break up with your current probiotic.

Not all probiotics are the same.

I think people often assume that if 10 billion bacteria are good…

100 billion must be ten times better.

That's not necessarily how this works.

If you're sensitive, you may want to start low and slow.

Something in the range of one to five billion CFUs may be a more reasonable starting point for some people, and then you can gradually adjust based on tolerance.

This is also where working with someone individually can really help.

At Oswald Digestive Clinic, we're not trying to put every single client on the exact same probiotic.

Because if one person has constipation, another has chronic diarrhea, another has severe bloating, and another has food reactions…

there's no reason to assume all four people need exactly the same thing.

The supplement should fit the person.

Not the other way around.

Another option is trying a single-strain probiotic rather than a huge blend with ten or fifteen different organisms.

If you're sensitive, that gives you fewer variables.

You can introduce one strain and actually see how your body responds.

And if it doesn't work, you have a much clearer idea of what you're reacting to.

We have some of the probiotic products we like linked below if you'd like to see examples.

But there's one more probiotic I want to mention because it's completely different from most of the bacteria we've been talking about.

Saccharomyces Boulardii

Saccharomyces boulardii is actually a beneficial yeast.

It's not a bacterial probiotic.

And it has some interesting properties.

It can produce a protease that may interfere with the ability of certain pathogenic organisms and toxins to interact with the intestinal lining.

It's been studied particularly in relation to organisms such as C. difficile and E. coli.

It has also been studied for anti-inflammatory and anti-secretory effects.

So in certain situations involving diarrhea, Saccharomyces boulardii may be an option worth considering.

Again, this doesn't mean everyone with diarrhea should immediately go buy it.

But it illustrates something really important:

The word "probiotic" describes a huge category of completely different organisms.

They're not interchangeable.

And finally, sometimes your digestive system really does just need a little time.

If your symptoms are mild, beginning with a smaller dose and gradually increasing can sometimes be easier than immediately taking the full recommended dose on the bottle.

Pay attention to your body's response.

Because with gut health, more is definitely not always better.

How Do You Choose a Probiotic?

Now there's one more piece of this that I don't want to leave out.

Because even if you've figured out which type of probiotic you want…

how do you know what's actually inside the bottle?

The probiotic aisle can honestly be ridiculous.

You've got 10 billion CFUs.

50 billion.

100 billion.

Five strains.

Ten strains.

Twenty strains.

Refrigerated products.

Shelf-stable products.

And every bottle basically tells you it's the best thing that's ever happened to your gut.

So how do you choose?

Strain and dose matter.

But quality matters too.

One study evaluated 13 probiotic products available in the United States and found that only two had contents that accurately matched their labels.

Some contained as little as 7% of the viable organisms claimed on the label.

Seven percent.

So the biggest number on the front of the bottle doesn't mean much if what's inside doesn't actually match what the company is claiming.

Look for reputable manufacturers that perform batch testing for potency and purity.

You can also look for independent testing from organizations such as ConsumerLab.

And this is something we're very intentional about when we're recommending supplements at the clinic.

We don't want somebody spending money on twelve different products just because they have good marketing.

We want to know:

What are we trying to accomplish?

Does this particular product make sense for that goal?

Is it a reputable product?

And is the person actually tolerating it?

Because ultimately, the "best probiotic" isn't necessarily the one with the most strains or the highest CFU count.

It's the one that makes sense for you and for the reason you're taking it.

What Should You Do If You're Experiencing Side Effects of Probiotics?

So if you're taking a probiotic right now and you're experiencing more gas, bloating, abdominal pain, diarrhea, allergy-type symptoms, or possible histamine reactions…

don't ignore what your body is telling you.

Sometimes you need time to adjust.

Sometimes you need a smaller dose.

Sometimes you need a different strain.

Sometimes there's another ingredient in the product causing the problem.

And sometimes the probiotic isn't really the problem at all, it's revealing that there's something else happening in your digestive system that needs to be investigated.

If you're dealing with ongoing digestive symptoms and you feel like you're constantly guessing about supplements, foods, or what your gut actually needs, that's exactly what we help people work through at Oswald Digestive Clinic.

70% of our clients get insurance coverage, and I’ll share a link here to schedule.

But before you go, there's another digestive symptom that can be really alarming when you first notice it:

black stool.

And while sometimes there's a completely harmless explanation, there are also situations where black stool is something you should take seriously.

So in this video right here, I break down five reasons your stool could be black, how to tell some of those causes apart, and when it's time to contact your doctor.

Click that video right here and watch that one next.

And until next time, stay curious.

Easily schedule your Initial Appointment here. 70% of our clients get insurance coverage, and the appointments are via privacy-secure Zoom video

Download Our FREE GUIDE: 5 WAYS TO IMPROVE GUT HEALTH

Curious about what type of gut you have? Take our Free Quiz now!