Ingredient evidence
Probiotics
A category where the specific strain matters enormously and almost nobody reads it. Most products are sold on a big number that tells you very little.
Also sold as: live bacteria, lactobacillus, vaginal probiotics.
Our read of the evidence
Mixed evidence
Trials disagree, or the effect is small and inconsistent.
Worth trying for recurrent BV alongside proper treatment. Generic high-CFU products are mostly marketing.
Strain, not species, not CFU
Probiotic effects are strain-specific. Lactobacillus rhamnosus GR-1 is a different organism from Lactobacillus rhamnosus GG, and evidence for one says nothing about the other. Any product listing only 'Lactobacillus rhamnosus' without the strain code is asking you to assume it is the studied one.
CFU count - the billions on the front of the box - is the number brands compete on because it is easy to inflate and easy to understand. More is not better. A well-studied strain at 1 billion CFU beats an unstudied one at 50 billion.
For vaginal health, the strains with the best supporting data are L. rhamnosus GR-1 and L. reuteri RC-14, studied both orally and vaginally, mostly as an adjunct to standard treatment for bacterial vaginosis to reduce recurrence. Evidence for preventing thrush is weaker.
When a probiotic is the wrong answer
Recurrent vaginal symptoms need a diagnosis before they need a supplement. Bacterial vaginosis, thrush and trichomoniasis feel similar and are treated completely differently. Self-treating the wrong one with a probiotic wastes months.
Any new discharge with a smell, bleeding between periods, pelvic pain or a change after a new partner should be assessed rather than supplemented. A probiotic is a reasonable thing to add after that, not before it.
For gut symptoms, the picture is genuinely mixed. Some strains help specific presentations of IBS; broad-spectrum products for general 'gut health' in people without symptoms have little to show for themselves. Fibre and dietary variety do more for most people than any capsule.
How to take it.
- Typical dose
- 1-10 billion CFU daily of a studied strain
- Form
- Capsule, sachet or drink; vaginal pessaries for some strains
- Timing
- Daily, usually with or just after food
- Worth knowing
- Give it four to eight weeks. Refrigeration requirements vary by product and matter for viability - check the pack.
What it will not do.
- It will not treat an active infection - that needs the right antibiotic or antifungal
- It will not permanently colonise your gut; most strains pass through
- It will not make a difference if the strain has never been studied
Who should avoid it.
- You are significantly immunosuppressed, or have a central venous line, without medical advice
- You are acutely unwell with an undiagnosed infection - get diagnosed first
Raise with a prescriber
- Separate from antibiotics by two to three hours if taking both
- No significant medicine interactions otherwise
Products containing probiotics.
Everything below is stocked in the UK. Compare on the active dose and the cost per day rather than the size of the pack.
| Product | Key actives | Form | Price | Per day | Best for |
|---|---|---|---|---|---|
| Water-Based ProbioticSymprove | Lactobacillus rhamnosus, L. plantarum, L. acidophilus, Enterococcus faecium | Liquid | £79/12-week course | £6.58 | IBS, Post-antibiotic gut, Hormonal skin flares |
| Wild Nutrition Multi Strain BioticWild Nutrition | Multi-strain live bacteria | Capsule | £45.50 | £1.52 | Gut symptoms after antibiotics, Trialling for four to eight weeks |
| ARTAH Enhanced SynbioticARTAH | Live bacteria, Prebiotic fibre | Capsule | £39.00 | £1.30 | Gut symptoms after antibiotics, Trialling for four to eight weeks |
| Together Health MultibioticTogether Health | Fermented food cultures | Capsule | £20.95 | 70p | Gut symptoms after antibiotics, Trialling for four to eight weeks |
| Igennus Live Cultures+ Lab4 ProbioticsIgennus Healthcare Nutrition | Lab4 consortium, Prebiotic | Capsule | £20.95 | 70p | Gut symptoms after antibiotics, A structured four-week trial |
Prices are the brand's UK list price at the time of writing and change often. Cost per day is calculated from pack size and the label's daily serving, and is shown only where both are published.
Common questions.
Do vaginal probiotics actually work?
Specific strains, notably L. rhamnosus GR-1 and L. reuteri RC-14, have evidence for reducing recurrence of bacterial vaginosis when used alongside standard treatment. Generic products with unnamed strains do not have that evidence.
Should I take a probiotic with antibiotics?
It can reduce antibiotic-associated diarrhoea for some strains. Take it a few hours apart from the antibiotic dose, and continue for a week or two afterwards.
How many CFU do I need?
Match the dose used in the studies for that specific strain, usually between 1 and 10 billion. A higher number on an unstudied strain is not an upgrade.
Can probiotics help with thrush?
The evidence is weaker than for bacterial vaginosis. Recurrent thrush deserves a proper assessment, including checking for underlying causes, rather than repeated self-treatment.
Where this comes from.
A supplement is not clinical care.
If symptoms are affecting your work, your sleep or your relationships, the useful next step is an assessment rather than another purchase. Our check-in takes three minutes and points you to the right kind of clinician.
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Other ingredients
Good evidence. Worth taking if you rarely eat oily fish, and genuinely important in pregnancy. Not a mood treatment on its own.
Good evidence. Vitamin D is a genuine UK public health recommendation. K2 is reasonable, optional and oversold.
Good evidence. Highly effective when you are deficient. Potentially harmful when you are not. Get tested.
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Food supplements are not medicines and are not intended to diagnose, treat or cure any condition. They should not replace a varied diet or prescribed treatment. If you are pregnant, breastfeeding, taking medication or managing a diagnosed condition, check with a pharmacist or clinician before starting anything on this page. We do not accept payment for inclusion or placement. Where a link earns us a commission we say so on the product page. Last reviewed 27 August 2026.