Probiotics are perhaps the most poorly understood category in the pharmacy. From yoghurt with live cultures to capsules with 50 billion bacteria — the differences are huge. Here is what science knows about probiotics in 2026 and how to choose well.
What probiotics are
The WHO defines probiotics as “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host”. The key is “in adequate amounts” — a yoghurt with 1 million CFU (colony-forming units) is NOT a probiotic in the therapeutic sense. For a clinical effect, you need 1-50 billion CFU per dose, depending on the strain.
The main families
Lactobacillus
The most studied genus. It lives mainly in the small intestine. Important strains:
- L. rhamnosus GG — studied for acute diarrhoea in children, antibiotic-associated diarrhoea and allergy prevention. More than 1200 clinical studies.
- L. acidophilus — a classic in yoghurt and fermented dairy products.
- L. plantarum — studied for irritable bowel and functional gastrointestinal symptoms.
- L. reuteri — reduces colic in infants (clear studies).
Bifidobacterium
It lives mainly in the colon. Main strains:
- B. longum — an immunomodulator, with potential for anxiety via the gut-brain axis (studies under way).
- B. infantis — very well studied for irritable bowel syndrome.
- B. bifidum — naturally present in breastfed infants.
Saccharomyces boulardii
It is NOT a bacterium but a yeast. It resists antibiotics — which is why it is the first choice for antibiotic-associated diarrhoea. The iconic brand: Enterol.
When they work — clear indications
Probiotics have real clinical evidence (not just marketing) in the following situations:
- Antibiotic-associated diarrhoea — prevention with S. boulardii or L. rhamnosus GG, started on day 1 of the antibiotic and continued for 7 days after.
- Acute viral diarrhoea in children — shortened by 1-2 days.
- Irritable bowel syndrome — specific multi-strain formulations (VSL#3, Alflorex, Symprove) can reduce symptoms in 30-50% of patients.
- Atopic dermatitis in infants — L. rhamnosus GG during pregnancy and breastfeeding reduces the risk of dermatitis.
- Bacterial vaginosis and recurrent cystitis — L. crispatus, L. jensenii, oral or intravaginal.
When they do NOT work — minor but important
- “Detox” — no, probiotics do not detoxify. The kidneys and the liver do that.
- Weight loss — no convincing evidence.
- General immunity in healthy adults — marginal effects.
- Recurrent candidiasis — probiotics do not treat fungal infections.
How to choose a probiotic
- The specific strain matters, not just the genus. “Lactobacillus” is not enough — the strain must be stated (L. rhamnosus GG, not just L. rhamnosus).
- CFU guaranteed until the expiry date — many manufacturers state the CFU at the time of manufacture. Look for “CFU guaranteed until expiry”.
- Match the strain to the indication — for antibiotic-associated diarrhoea, choose S. boulardii (Enterol) or L. rhamnosus GG (Linex). For irritable bowel, clinically tested multi-strain formulations.
- The right form — gastro-resistant capsules protect the strains from stomach acid. A powder without protection — reduced effectiveness.
- Storage — some strains need refrigeration (check the label). Others are stable at room temperature.
Popular products in Romanian pharmacies
- Linex — L. acidophilus + B. bifidum. Prices on HartaFarmacii.
- Enterol 250 mg — S. boulardii. The reference for diarrhoea.
- Symbiocare / BioGaia — L. reuteri for children.
- Ecobalance / Fargan — multi-strain, popular in Romania.
How to take them correctly
- In the morning, on an empty stomach, 30 min before a meal — this maximises survival through the stomach (higher pH in the morning).
- With antibiotics — 2-3 hours apart (the antibiotic kills the probiotic in suspension). Exception: S. boulardii, which resists antibiotics.
- At least 4 weeks to see effects in irritable bowel syndrome.
- During antibiotic treatment — from day 1 of the antibiotic, continue for 7-14 days after.
A probiotic-friendly diet — a natural complement
Capsule supplements are effective, but a diet with naturally fermented foods supports the microbiome continuously:
- Yoghurt and kefir — sources of Lactobacillus. Choose plain yoghurt, not one with added fruit (high sugar content).
- Fermented cheese — mature telemea (brined white cheese), aged cașcaval (yellow cheese).
- Natural pickles (not preserved in vinegar!) — sauerkraut, traditionally pickled cucumbers.
- Kimchi, kombucha, miso — if you have access to them; concentrated sources.
- Prebiotic fibre — onion, garlic, leek, Jerusalem artichoke, green bananas, oats. They feed the beneficial bacteria already present.
Side effects and contraindications
Probiotics are safe for the vast majority of people, but some situations call for caution:
- Severely immunocompromised people (active chemotherapy, a recent transplant, uncontrolled HIV) — a rare risk of bacterial translocation. Talk to your doctor.
- Premature babies or children with central catheters — generally avoided.
- Bloating and wind in the first few days — normal, it settles within 3-5 days. If it persists, change the strain.
- Allergic reactions to excipients (lactose, soya) — read the label.
A pragmatic conclusion
Probiotics work, but not universally. For clear situations (antibiotic-associated diarrhoea, acute diarrhoea in children, colic in babies, irritable bowel), choose studied strains at the right dose. For “general immunity”, eat fermented vegetables (pickles, kimchi, yoghurt). The savings are real — do not buy expensive formulations without an indication. Compare prices in the HartaFarmacii Probiotics category.
Frequently asked questions
- Should I take probiotics when I am on an antibiotic?
- Yes, the evidence is clear — S. boulardii (Enterol) or L. rhamnosus GG reduce the risk of antibiotic-associated diarrhoea by 40-50%. Start on day 1 of the antibiotic and continue for 7-14 days after. Take them 2-3 hours apart from the antibiotic.
- What is the difference between Lactobacillus and Bifidobacterium?
- Lactobacillus dominates the small intestine, Bifidobacterium dominates the colon. Both are beneficial, but with indications specific to each strain. Multi-strain formulations (Lacto + Bifido) are often more effective.
- Do probiotics need to be kept in the fridge?
- It depends on the product. Some strains (especially freeze-dried and well-packaged ones) are stable at room temperature. Others (many in powder or suspension form) need 2-8°C. Read the label.
- How long should I take probiotics for?
- For antibiotic-associated diarrhoea: the length of the antibiotic course + 7-14 days. For irritable bowel: at least 4 weeks, often 8-12 weeks for an effect. For general prevention: there is no clear evidence — a permanent course is not worth it.
- Does a probiotic yoghurt replace a capsule?
- Not in general. Classic yoghurt has 10-100 million CFU, too little for a therapeutic effect. “Activia” or “LGG” yoghurts have more, but still far from the doses in capsules (1-50 billion CFU).