Probiotics are available today in capsules, sachets, drops, fermented products and formulas designed for different age groups and specific needs. They are most commonly used during and after antibiotic therapy, for certain digestive complaints or to support the balance of the gut microbiota. However, the fact that a product contains “good bacteria” does not automatically mean that it is suitable for every person or every health problem.

The most important fact about probiotics is that not all probiotics are the same. Their effects depend on the exact microorganism, strain, quantity, method of use and the health condition for which they are taken. Research results obtained for one strain cannot automatically be applied to all other probiotics.

Key points: a good probiotic should not be chosen only according to the number of billions of microorganisms or the number of strains. Check the full strain name, recommended purpose, dosage, expiry date, storage conditions and whether the number of live microorganisms is guaranteed until the end of the shelf life.

What are probiotics?

Probiotics are live microorganisms that, when administered in adequate amounts, may provide a health benefit to the host. For a microorganism to be properly classified as a probiotic, it is not enough for it to occur naturally in the gut or in fermented foods. It must be precisely identified, safe for its intended use and studied in an appropriate quantity.

Probiotics may belong to different groups of bacteria, as well as yeasts. The best-known include microorganisms from the former broad Lactobacillus group and related genera, Bifidobacterium, Streptococcus thermophilus and the probiotic yeast Saccharomyces boulardii.

It is important to distinguish probiotics from the gut microbiota. The gut microbiota, sometimes called the intestinal flora, is the complex community of microorganisms that naturally live in the digestive tract. A probiotic product contains only one or several carefully selected microorganisms and does not represent the entire gut microbiota.

Probiotics, gut microbiota and digestive health

Probiotic, prebiotic, synbiotic and postbiotic – what is the difference?

These terms are often used as though they mean the same thing, but they describe different products and components.

Term What it means Important note
Probiotic A live microorganism with a demonstrated benefit when used in an adequate amount. The benefit must be linked to a specific microorganism, dose and intended use.
Prebiotic A substrate that is selectively used by the host’s microorganisms and provides a health benefit. Certain fibres may have prebiotic properties, but not all fibres are prebiotics.
Synbiotic A combination of live microorganisms and an appropriate substrate. Simply combining any probiotic with any type of fibre does not necessarily create an effective synbiotic.
Postbiotic A preparation of inanimate microorganisms and/or their components with a demonstrated health benefit. A postbiotic is not simply a product in which probiotic bacteria have accidentally died.
Fermented food Food produced through the controlled action of microorganisms and their enzymes. Not every fermented food is automatically a source of probiotics.

Do yoghurt, kefir and sauerkraut contain probiotics?

Yoghurt, kefir, sauerkraut, kimchi and other fermented foods may contain live microorganisms, but this does not automatically make them probiotics. In traditionally fermented foods, the exact strains, their quantity and whether they remain alive until consumption are often unknown.

Some commercially produced foods may contain an added, clearly identified and studied probiotic strain. In such cases, the label should be checked carefully. Fermented foods can be part of a varied diet, but they are not necessarily a substitute for a preparation containing a specific strain in a standardised amount.

Species, strain and CFU – what should you really check?

The name of a probiotic microorganism may contain three important parts: genus, species and strain. Two microorganisms may belong to the same species but to different strains and may not have the same effects.

For this reason, a high-quality product label should state the full name, including the strain designation. A statement that a product contains only “lactobacilli” or “bifidobacteria” does not provide enough information about what the preparation has been studied for.

CFU stands for colony-forming units and is used to express the approximate number of live, viable microorganisms. Labels therefore often state millions or billions of CFU.

More billions do not automatically mean a better product. A preparation with a smaller amount of a well-studied strain may be a more rational choice than a product with a very high number of microorganisms but no clearly stated purpose or supporting evidence. It is also important that the declared quantity is guaranteed until the end of the shelf life, rather than only at the time of manufacture.

The most commonly used probiotic microorganisms

Group of microorganisms Where they may be found What you should know
Lactobacilli and related genera Probiotic preparations, fermented dairy products and other fermented foods. There are many different species and strains. They cannot all be used for the same purpose.
Bifidobacterium A natural part of the gut microbiota and a common ingredient in probiotic formulations. Selection should be based on the exact strain, dose and intended population.
Streptococcus thermophilus A starter culture used in yoghurt production and an ingredient in certain formulations. Its presence in a fermented product alone does not prove a probiotic effect.
Saccharomyces boulardii Preparations intended for certain forms of diarrhoea and use alongside antibiotics. It is a yeast rather than a bacterium. It is not suitable for everyone and requires particular caution in severely ill or immunocompromised patients.

A list of microorganisms on the package is not enough to conclude that a preparation will work for every problem. The most reliable choice is a product that clearly states the strain, quantity, recommended use and method of administration.

When are probiotics used?

Probiotics are most commonly used as additional support in situations where there is a risk of disrupting the balance of the gut microbiota or where a particular strain has been studied for a specific health benefit. They are not a universal treatment and do not replace medicines, oral rehydration, an appropriate diet or medical assessment.

Probiotics with antibiotics

Antibiotics act against bacteria that cause infection, but they may also affect some of the microorganisms that naturally live in the digestive tract. Some people develop loose stools or antibiotic-associated diarrhoea during or after treatment.

Certain probiotic strains and combinations may reduce the risk of antibiotic-associated diarrhoea, but the effect is not the same for every preparation. A probiotic should therefore not be selected only because the package says “for use with antibiotics”, but according to its label and the advice of a pharmacist or doctor.

  • For bacterial probiotic cultures, a time interval from the antibiotic is often advised, in accordance with the instructions for the specific product.
  • Saccharomyces boulardii is a yeast, so antibacterial antibiotics do not act on it in the same way as they act on bacterial probiotics.
  • A probiotic does not eliminate the adverse effects of antibiotics and is not a reason to change or stop prescribed treatment without medical advice.
  • The duration of use after antibiotics is not universal and depends on the product, treatment, age and health status.

If severe or frequent watery diarrhoea, blood in the stool, fever, intense abdominal pain, marked weakness or signs of dehydration occur during antibiotic therapy, medical advice should be sought.

Acute diarrhoea

In acute diarrhoea, the priority is to prevent the loss of fluids and electrolytes. Oral rehydration solutions have a more important and immediate role than any probiotic supplement. Certain probiotic strains may be used as an additional measure, but the choice depends on the cause, age and severity of symptoms.

A probiotic should not be presented as a product that immediately “stops” every episode of diarrhoea. Diarrhoea may be caused by a viral or bacterial infection, antibiotics, food intolerance, chronic disease, travel or another condition requiring a different approach.

See the available products for diarrhoea and oral rehydration, while always checking the label and respecting age restrictions.

Bloating, gas and sensitive digestion

Bloating and gas do not always have the same cause. They may be associated with diet, eating too quickly, intolerance to certain foods, constipation, irritable bowel syndrome or other digestive disorders.

Some probiotic strains may help certain people, but the claim that every probiotic relieves bloating is not justified. If symptoms become worse, persist for a long time, interfere with daily life or are accompanied by weight loss, bleeding or severe pain, the underlying cause should be investigated.

Irritable bowel syndrome

Research results on probiotics in irritable bowel syndrome are not consistent. Some people may experience improvement in particular symptoms, while others may notice no benefit or may develop increased bloating. It should not be assumed that any randomly selected probiotic will relieve pain, cramps, constipation and diarrhoea at the same time.

Read more about symptoms and the correct approach in the guide Irritable bowel syndrome – a major problem in modern society.

Constipation

For constipation, a probiotic is not the first or only measure. Adequate fluid intake, a gradual increase in dietary fibre, physical activity and a regular bowel routine have a fundamental role. Certain probiotic strains may affect stool frequency or consistency, but this effect should not be generalised to all products.

Travel

Changes in food, water, time zone and daily routine may cause digestive discomfort. Some people use probiotics before and during travel, but no preparation can replace safe drinking water, hand hygiene and careful food selection. Evidence for the prevention of travellers’ diarrhoea differs between strains and products.

Probiotics for children

Products for adults are not automatically suitable for babies and children. For children’s preparations, check:

  • the minimum age for use;
  • the exact strain and quantity in the daily dose;
  • the dosage form and preparation method;
  • the presence of allergens, sweeteners and other additives;
  • storage conditions after opening;
  • whether the product is used independently or alongside prescribed treatment.

Probiotics should not be given to infants, premature babies, children with a weakened immune system, serious chronic illness or a central venous catheter without prior assessment by a paediatrician.

Diarrhoea and vomiting in children may quickly lead to dehydration. Dry mouth, reduced urination, absence of tears, sunken eyes, unusual sleepiness or marked irritability require prompt assessment by a healthcare professional.

Probiotics during pregnancy and breastfeeding

Pregnancy and breastfeeding are not periods in which supplements should be taken at random simply because they are marketed as “natural”. Safety and suitability must be assessed according to the exact composition, dose, reason for use and the woman’s health status.

A probiotic should not be presented as a stand-alone treatment for vaginal candidiasis, bacterial vaginosis, urinary tract infections or other complaints. Itching, burning, pain, an unpleasant smell, unusual discharge or recurrent infections require examination and appropriate diagnosis.

Pregnant and breastfeeding women should use only preparations that are suitable for this period according to the label and the advice of a gynaecologist, doctor or pharmacist.

How should you choose the right probiotic?

When choosing a product, it is not enough to look at the front of the package. The most important information is usually found in the ingredients list, directions for use and product instructions.

What to check Why it matters
Genus, species and strain This makes it possible to connect the specific product with evidence for a particular use.
Quantity per daily dose The number per capsule is not enough if the recommended daily dose contains several capsules.
Guaranteed quantity until expiry The number of viable microorganisms may decrease during storage.
Recommended purpose A product for use with antibiotics is not necessarily the best choice for constipation, bloating or everyday use.
Storage conditions Some preparations require refrigeration, while others are stable at room temperature.
Use after opening This is especially important for drops, liquids and larger packages.
Age restrictions and warnings Not all preparations are suitable for children, pregnant women or people with chronic conditions.
Allergens and additional ingredients A product may contain traces of milk, soya, gluten, sugars, polyol sweeteners or other components.

When and how should a probiotic be taken?

There is no single rule that applies to every preparation. Some are taken with food, some before meals, while certain powdered formulas need to be dissolved and left for a specified period before use. The directions for the specific product should therefore always be followed.

  • Do not dissolve a probiotic in very hot water, tea or another hot drink unless the manufacturer specifically states that this is permitted.
  • Do not open a capsule and mix its contents with food without checking whether this is allowed.
  • When using a probiotic with antibiotics, follow the interval specified for the particular preparation.
  • Do not take a double dose after forgetting one, unless the instructions state otherwise.
  • Follow the stated storage conditions and the period of use after opening.

A probiotic does not necessarily have to permanently colonise the gut in order to have an effect. Many probiotic microorganisms act while passing through the digestive tract, and their presence may be temporary.

How long should probiotics be taken?

The duration of use depends on the reason for taking the product, its composition and the individual response. There is no universal rule that every probiotic should be used for seven days, two weeks or several months.

For short-term use with antibiotics or acute digestive symptoms, follow the recommendation for the specific product. For persistent symptoms, it is not rational to keep changing products for months without investigating the underlying cause.

If no benefit is noticed after a reasonable trial period, or if symptoms become worse, the product choice and the health problem for which it is being used should be reassessed.

Does a probiotic have to be stored in the refrigerator?

Not every probiotic requires refrigeration. Stability depends on the strain, manufacturing process, packaging, moisture and temperature. Some modern products may be stored at room temperature, while others require an uninterrupted cold chain.

The safest approach is to follow the label. A product that requires refrigeration should not be left for long periods in a hot car, near a heat source or in direct sunlight. A preparation should also not be frozen unless this is specifically recommended.

Adverse effects and who should be cautious

Probiotic preparations are generally well tolerated by healthy people. Temporary bloating, gas or a change in bowel habits may occur at the beginning of use. This does not mean that worsening symptoms are a necessary sign that the product is “starting to work”.

Particular caution is required in:

  • people with a severely weakened immune system;
  • seriously ill and hospitalised patients;
  • people with a central venous catheter;
  • premature infants;
  • patients who have undergone major surgery;
  • people with severe impairment of the intestinal barrier;
  • patients taking antifungal medicines when the product contains a probiotic yeast.

In these groups, a probiotic should not be introduced routinely without medical assessment. Although serious complications are rare, the risk is not the same for a healthy adult and a severely ill or immunocompromised patient.

Seek medical advice without delay if any of the following occur:

  • bloody or black stools;
  • severe or worsening abdominal pain;
  • high temperature with digestive symptoms;
  • marked weakness, dizziness or confusion;
  • persistent vomiting and inability to drink fluids;
  • signs of dehydration;
  • unexplained weight loss;
  • persistent or frequently recurring complaints.

Common facts and myths about probiotics

Claim Fact or myth? Explanation
All probiotics are the same. Myth The effect depends on the genus, species, strain, dose and intended use.
A product with more strains is always better. Myth The number of strains is not a substitute for good evidence and an appropriate formulation.
More billions of CFU always mean a stronger effect. Myth The appropriate dose depends on the particular strain and the intended purpose.
Every fermented food is a probiotic. Myth The microorganisms are often not identified, standardised or studied for a health benefit.
Probiotics can replace prescribed medicines. Myth They may provide additional support but do not replace antibiotics, antifungals or other prescribed treatments.
A probiotic may cause gas or bloating. Fact Mild temporary complaints are possible, but persistent worsening should not be ignored.
Not every probiotic preparation is suitable for everyone. Fact Age, pregnancy, immune status, chronic illness and current treatment influence selection and safety.

How can you find a product for a specific need?

Available products include single-strain preparations, combinations of several microorganisms and formulas containing prebiotics, vitamins or minerals. They are not interchangeable and should be selected according to the label, age and intended use.

Need Example category or product What to consider
Overview of probiotic preparations Probiotic preparations Compare the strains, dose, purpose, age restrictions and storage requirements.
Synbiotic formulation Multilac synbiotic capsules Check the full composition and instructions for use alongside antibiotic therapy.
Multi-strain bacterial product Probiotic capsules The number of strains alone is not enough; check the dose and recommended purpose.
Formula containing probiotic yeast Esenbak Pro & Byo S. boulardii It is not suitable for everyone; particular caution is required in severely ill and immunocompromised people.
A wider range of targeted formulations PILEJE Lactibiane and Babybiane products Choose according to age and intended use, rather than according to the brand alone.
Digestive complaints and gut microbiota Digestion and diarrhoea products Oral rehydration is the priority in diarrhoea; persistent complaints require medical assessment.

The listed products are examples of available formulations and do not represent a universal recommendation for every user. Before purchasing, read the label, warnings, instructions for use and age restrictions.

Pharmacist’s advice

Always choose a probiotic according to the reason for using it, rather than according to the highest number of bacteria shown on the front of the package. Check whether the full strain names, quantity per daily dose, expiry date and storage conditions are clearly stated.

During antibiotic therapy, do not stop or change the antibiotic without medical advice because of digestive symptoms. Check when the specific probiotic should be taken in relation to the medicine. In diarrhoea, first replace fluids and electrolytes. Seek medical advice if there is blood in the stool, fever, severe pain, marked weakness or signs of dehydration.

Ljubica Barbulović, Master of Pharmacy

Related topics on digestive health

Frequently asked questions about probiotics

Is it good to take a probiotic every day?
Some products may be intended for everyday use in healthy people, but this does not mean that long-term use is always necessary. The reason for use, strain, dose and effect should be reviewed periodically.

What is the best time to take a probiotic?
It depends on the product. Some are taken with food, some before meals and some formulas have a specific preparation method. The instructions for the particular preparation should always be followed.

How much time should there be between an antibiotic and a probiotic?
A time interval is often recommended for bacterial probiotics, but the exact timing should be checked in the instructions for the specific product. Saccharomyces boulardii is a yeast, and antibacterial antibiotics do not act on it in the same way.

Can a probiotic cause diarrhoea or bloating?
Temporary changes in digestion, gas or bloating are possible. If symptoms are severe, persistent or become worse, stop the product and seek advice from a pharmacist or doctor.

Do more billions mean that a probiotic is better?
No. The CFU count must be considered together with the exact strain, purpose, daily dose and evidence for the particular formulation.

Is a product with ten strains better than one with a single strain?
Not necessarily. A well-studied single strain may be more appropriate than a mixture of many microorganisms without a clearly defined purpose.

Can yoghurt replace probiotic capsules?
It depends on the purpose and the product. Fermented food may be a valuable part of the diet, but it usually does not provide a standardised quantity of a specific probiotic strain.

Do probiotics permanently colonise the gut?
Many probiotic microorganisms pass through the digestive tract and remain only temporarily. Permanent colonisation is not necessary for a particular strain to have an effect.

Can a probiotic be taken together with an antifungal medicine?
If the preparation contains a probiotic yeast, an antifungal medicine may affect its viability or effect. The combination should be checked with a pharmacist or doctor.

Can children use probiotics intended for adults?
Not automatically. Age, dose, dosage form, composition and warnings must be checked. In babies and children with serious health conditions, assessment by a paediatrician is required.

Can pregnant women use probiotics?
Certain preparations may be suitable during pregnancy, but safety cannot be assumed for every product. The exact composition should be checked and advice obtained from a gynaecologist, doctor or pharmacist.

Can a probiotic replace treatment for candidiasis or a bacterial infection?
No. A probiotic may only provide additional support when appropriate. It does not replace diagnosis, antibiotics, antifungal medicines or other prescribed treatment.

Conclusion

Probiotics may be useful, but only when they are selected and used correctly. The microorganism name, strain designation, appropriate quantity and intended purpose are more important than marketing expressions such as “maximum strength”, “complete restoration of the intestinal flora” or “the highest number of billions”.

There is no single best probiotic for every person and every complaint. A product intended for use with antibiotics may not be a rational choice for constipation, bloating, pregnancy or everyday use. When symptoms are severe, persistent or accompanied by warning signs, a food supplement should not delay medical assessment and diagnosis.