Probiotic supplements compared

Daily maintenance. 1 capsule per day with a meal or 30 minutes before, most days of the week. Strain identity matters more than CFU count — 5 billion CFU of LGG outperforms 50 billion CFU of unnamed strains.

During antibiotics. Take Saccharomyces boulardii (Florastor or generic) starting on day 1 of the antibiotic course, 2 capsules daily spaced 2+ hours from the antibiotic dose. Continue for at least 7 days after the antibiotic ends. For Lactobacillus strains, wait until the antibiotic course is finished — most lactobacillus strains get killed by the antibiotic.

Refrigeration. Most modern probiotics are shelf-stable for 18–24 months at room temperature. If the label doesn't say "Keep refrigerated," you don't need to. Genuinely cold-chain products (Visbiome) ship in cold packs and should be refrigerated on arrival.

Course length. For specific conditions (post-antibiotic, traveller's diarrhoea), 2–4 weeks is typical. For general maintenance, indefinite daily use is safe based on available evidence. There's no documented harm from long-term use of well-characterised strains.

Empty stomach vs with food. Most modern strains are acid-resistant and don't require empty-stomach dosing. Take with food if you notice any GI discomfort.

Generally safe. Probiotics have an excellent safety record across all age groups in healthy adults. Most adverse events are mild (transient bloating or gas in the first 1–2 weeks of use). NIH ODS rates the overall safety as "very good" for healthy populations.

Immunocompromised patients. Rare cases of bacteremia or fungemia have been reported in severely immunocompromised patients (post-chemotherapy, central venous catheter, short-bowel syndrome). Saccharomyces boulardii has a specific warning for catheter patients because the yeast can colonise the catheter surface. If you fall in this group, consult your physician before starting any probiotic.

SBO / IBS severe cases. People with small-intestinal bacterial overgrowth (SBO) often feel worse on probiotics — extra bacteria in the wrong place can amplify bloating. If symptoms worsen after starting, stop.

Pregnancy and children. Lactobacillus and Bifidobacterium strains have been studied in pregnancy and infancy with reassuring safety data. Saccharomyces boulardii is generally considered safe but has less data in pregnancy. Always check with your OB-GYN or paediatrician.

Drug interactions. Probiotics can interfere with immunosuppressants. S. boulardii and antifungal medications are a specific interaction (the antifungal will kill the yeast probiotic, defeating the purpose).