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Saccharomyces boulardii is a unique yeast and microorganism. This strain from OptiBac is scientifically proven to reach the gut alive.

Vegetarian Vegetarian
No Dairy No Dairy
No Gluten No Gluten

What's it for?

An extensively researched microorganism, proven to reach the gut alive.

Who's it for?

For anyone, 1 year and over, seeking a pure Saccharomyces boulardii supplement.

Each capsule:

Provides 5 billion live cultures of pure, shelf stable Saccharomyces boulardii.

OptiBac Saccharomyces boulardii

Saccharomyces boulardii is a natural and safe microorganism with vast scientific research and documentation.

This strain has been internationally acclaimed as a well-researched and unique microorganism, and has been safely used for the last 50 years. Saccharomyces boulardii is a natural food supplement, and not a medicine.

Saccharomyces boulardii is a unique microorganism which is sold widely in the US, Scandinavia, Germany & France. This friendly yeast is more robust to environmental stressors than more common bacterial live cultures, and shows strong resistance to heat, humidity and stomach acidity levels. These live cultures of S. boulardii have been tested and shown to be especially stable and resistant.

For more information healthcare professionals can read Scientific Research on S. boulardii or our FAQ, What is S. boulardii.

Saccharomyces boulardii under the microscope

More about OptiBac

All we do is live cultures; looking at different species and strains in detail. We are partnered with some of the world's leading institutes of microbiology; so when you're stressed with too much on your mind, you can rest easy - confident that you're choosing the experts.


Saccharomyces boulardii can be given to adults and children (from 1 year and over) with the following recommendations, or as professionally directed.

  • Take one to four capsules depending on severity of symptoms and up to six capsules daily, or as professionally directed
  • If taking anti-fungals, take separately (at least 2 hours apart).
  • For infants and children the dose should be lowered

  • Drink plenty of water with your course of live cultures.

  • For anyone unable to swallow capsules, capsule can be opened and contents mixed with a cold meal or beverage.

    See also Can I take 2 OptiBac supplements at the same time?


Like the rest of the OptiBac range, Saccharomyces boulardii does not require refrigeration.

Store out of direct sunlight.


Live cultures are not recommended for those with serious medical conditions eg. those who are severely immunosuppressed, have pancreatitis, are in the ICU, have melaena, have a central venous catheter, infants with short bowel syndrome, or to patients with open wounds following major surgery; unless under a doctor's care. Furthermore, pregnant or breastfeeding women should consult their doctor before taking Saccharomyces boulardii, 'For travelling abroad', or natural plant extracts as in 'For daily immunity'.

Nutritional Information

Live cultures: Saccharomyces boulardii (250mg); vegetarian capsule: hydroxypropyl methylcellulose; titanium dioxide; stabiliser: potato starch; anti-caking agents: vegetable magnesium stearate; silicon dioxide.

Each capsule guarantees 5 billion live cultures.

Suitable for vegans & vegetarians.

Frequently Asked Questions

Healthcare professionals can follow the links below to read FAQs relevant to 'Saccharomyces boulardii'.

You can find more of our frequently asked questions on our FAQ page.


Delivery Options


As we are an UK-based company, the product prices on our website will always be shown in pounds sterling (GBP £). As currency exchange rates fluctuate on a daily basis, the conversion to local currency will be made by your bank on the day of purchase. Check out today's currency conversion rates using a search engine and an appropriate currency conversion tool, though do bear in mind that the rates displayed may be subject to change before your bank processes your transaction.

Same day dispatch

For most delivery options, if you place your order by 3pm on a working day (i.e. Monday to Friday, excluding bank holidays), we'll dispatch it on the same day. Any orders after this time will be dispatched on the next working day.

If you choose our International Express Courier option, the cut-off time is 11am.

United Kingdom

Delivery within the United Kingdom and Northern Ireland has a fixed price, regardless of the size and weight of your order. Delivery times are estimates and not guaranteed unless otherwise stated.

Method Price
Standard Shipping
Please allow 4-7 days for delivery.

First Class Postage
Please allow 1-3 days for delivery.

Next Day Courier
Guaranteed next-working-day delivery to most of the UK if you order by 3pm Monday to Friday (requires signature).



We ship to virtually all countries around the world, with the notable exception of Hong Kong.

Most international delivery prices are dependent on the size of your order and where it's being sent. You'll be shown the final price of shipping in the checkout, before payment, once we have your address and order details.

The main exception to this is delivery to EU countries using our International Express Courier service. This has a fixed delivery cost for each country, regardless of the size of your order.

Please note that not all services are available to all destinations. See our International Delivery Coverage table for the availability of each service for your country.

Method Price
International Standard
Please allow 3-7 days for delivery within Europe and 5-12 days to all other destinations. (Does not include tracking).
International Signed
International postage with delivery confirmation (requires signature).
Please allow 3-7 days for delivery within Europe and 5-12 days to all other destinations.
International Tracked & Signed
International delivery with full tracking and delivery confirmation (requires signature).
Please allow 3-7 days for delivery within Europe and 5-12 days to all other destinations.
International Express Courier
Fast international courier service with full tracking and delivery confirmation (requires signature). Delivers to USA and most other countries in 2-7 days. See our International Delivery Coverage for the delivery time to your country.

Remember: the price of international delivery depends on the size of the order and the country to which it's being sent. The final price of shipping will be shown in the checkout before you pay.

NB: Long distance shipping and short-term exposure to high temperatures will not compromise the viability of our products. Customers living in very hot countries should store the products out of direct sunlight and refrigerate if the option is available.

  • I honestly think these may have saved my mother's life. She'd had surgery for bowel cancer and caught Clostridium difficile in hospital - who sent her home. The vomiting and diarrhea were violent and dangerous for an 80 year old. I did a search of the literature and found an in vitro study of Saccharomyces boulardii for C. diff. and emailed from Brisbane to see if she could get it. She found the Optibac product, ordered it, and got better with the first dose. She showed it to her doctors at Gartnavel who went on to develop faecal transplants, so I even wonder if this gave them the idea! My mum was a biochemist, so she could read the papers I sent her.

    Brisbane (Mum's in Glasgow)
  • Have found Optibac very helpful thank you

  • Suffered loose bowel, flatulence and great discomfort (often acute stomach pain) for a month or more. I called OptiBac to find out what their products could do for me. This product was recommended,... Read more

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