Key points about probiotics

  • Probiotics are living bacteria and yeasts which, when taken in the right amount, can improve your health.
  • Probiotics are available over-the-counter (OTC) at pharmacies, “health” stores and supermarkets, as capsules or powders.
  • There are a number of different probiotic dietary supplements on the market, each having different species and strains of bacteria and yeasts.
  • Different probiotics may be useful for different conditions. Check with your pharmacist or read the label to make sure you’ve chosen the right probiotic for your needs.
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Probiotics are living bacteria and yeasts which, when taken in the right amount, can improve your health. 

Bacteria and yeasts (microbiota) are found all around us and on us – on our skin and in our digestive system and reproductive areas. It was once thought that all bacteria were bad for us, but now we know that some can help us stay healthy.

Research shows that the balance of bacteria, especially in your digestive system, may be important to managing your overall health. Taking a probiotic supplement may promote health by maintaining a natural balance of bacteria and reducing the growth of harmful bacteria. Capsules or powders containing beneficial bacteria or probiotics can be bought from pharmacies, health shops and supermarkets.

You may think about taking a probiotic supplement:

  • to prevent side effects associated with antibiotics such as diarrhoea
  • to help manage vaginal thrush or oral thrush
  • to help manage irritable bowel disease
  • to help manage eczema
  • to prevent urinary tract infections
  • alongside treatments for depression and anxiety.

Not all probiotic strains are created equally. We’re learning that specific strains of probiotic bacteria may have a role for a specific condition. One probiotic supplement may not help all conditions. 

Unlike medications, probiotics do not need to be approved by the medicines regulatory organisation in New Zealand called Medsafe. This means that manufacturers can sell supplements simply with "claims" of safety and effectiveness.

  • Research on probiotics and health conditions are very much cutting edge science.
  • Currently, researchers are undecided if probiotics are effective. Some say probiotics are effective; others believe they offer no benefit whatsoever.
  • It also remains unclear which probiotics (or combination of probiotics) work to treat certain diseases.
  • Despite these issues, some studies have shown positive results.
  • Ongoing research is needed to confirm that probiotics are a safe and effective treatment for certain conditions.

Protection against diarrhoea (runny poos) caused by antibiotics

  • Diarrhoea can happen in 5–30 out of every 100 people prescribed antibiotics and is more common with some antibiotics, such as penicillin-type antibiotics, cephalosporins and clindamycin. 
  • When taken in sufficient amounts, probiotics appear to reduce the risk of diarrhoea caused by antibiotics, in children and adults. This protective ability has been associated with different types of antibiotic and different probiotics.1
  • If you are taking antibiotics, you need to choose a supplement that contains between 5 and 40 billion CFU/day of a probiotic organism in order to experience any benefit.
  • Read more about diarrhoea.


Treatment of vaginal thrush (vaginal candidiasis)

  • Vaginal thrush is a common yeast infection that affects most women at some stage. Common symptoms include pain, itching and vaginal discharge. Taking antibiotics and being post-menopausal can increase their risk of getting vaginal thrush. 
  • Using a probiotic alongside antifungal treatment for thrush may help control the condition in the short term, but not necessarily for recurrent thrush.2
  • Choose a lactobacillus containing probiotic. 
  • Read more about vaginal thrush and treatment for vaginal thrush.

Protection against oral thrush

  • Oral candidiasis (thrush) can be a common condition in elderly people, as a side effect of medication or an indication of overall health.
  • Using a probiotic can reduce the risk of developing oral thrush.3

Probiotics for irritable bowel syndrome (IBS)

  • The evidence to support the use of probiotics in irritable bowel syndrome is inconclusive (not clearly for or against).
  • A 4 week trial of probiotics in the form of yoghurts or other fermented milk products can be considered, however, some of these products also contain ingredients that may worsen IBS symptoms, such as fructans, fructose or lactose.
  • A recent systematic review has concluded that there is some evidence that probiotics, e.g. Lactobacillus, may improve the overall symptoms, abdominal pain, bloating and distension in patients with IBS. However, there is little or no evidence that they will improve other symptoms such as diarrhoea, constipation and flatus.4

Probiotics for eczema

  • The role of probiotics in preventing eczema is inconclusive (not clearly for or against).
  • Initial results of a study in New Zealand found that a probiotic involving a bacterium named L. rhamnosus HN001 reduced eczema cases by a half at the age of two years. The other probiotics studied had no effect on eczema.6  
  • Read more about eczema.

Probiotics for urinary tract infections

  • Urinary tract infections (UTIs) occur in kidneys, ureters, urethra or bladder. Probiotics are thought to work by preventing bacteria that cause infection from climbing up the urinary tract and causing infection. The currently available evidence shows that probiotics do no reduce the risk of UTI in adults and children.7
  • Read more about UTIs.

Probiotics for mental health conditions

  • This is cutting edge research, but indications are that certain probiotics may be useful in managing depression and anxiety.8,9
  • Bacteria found in our digestive system can help our gut talk to our brain. Many of the chemicals needed to regulate mood are produced in our gut.
  • Read more about depression and anxiety.

Probiotics can cause side effects, although not everyone gets them. 

Side effects What should I do?
  • Feeling sick (nausea) or vomiting (being sick)
  • Stomach upset
  • Stomach gas or bloating
  • Tell your doctor or pharmacist if troublesome
  • Signs of infection such as high fever, chills, persistent cough
  • Tell your doctor immediately or ring HealthLine 0800 611 116
  • Signs of an allergic reaction such as rash, itching, swelling of the face, tongue or throat, or difficulty breathing
  • Tell your doctor immediately or ring HealthLine 0800 611 116
Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product(external link)

The following link has more information on probiotics.
How to make the most of probiotics(external link) Healthy Food Guide


  1. Do probiotics provide effective and safe protection against antibiotic-associated adverse effects(external link)? Best Practice Journal, June 2015
  2. Probiotics for vulvovaginal candidiasis in non‐pregnant women(external link) Cochrane Library, 2017 
  3. A meta-analysis of randomized trials assessing the effects of probiotic preparations on oral candidiasis in the elderly.(external link) Arch Oral Biol. 2017 Nov;83:187-192
  4. Systematic review with meta-analysis: the efficacy of prebiotics, probiotics, synbiotics and antibiotics in irritable bowel syndrome.(external link) Aliment Pharmacol Ther. 2018 Nov;48(10):1044-1060
  5. Irritable bowel syndrome in adults: Not just a gut feeling(external link) Best Practice Journal, February 2014
  6. Probiotics prove benefits in combating eczema(external link) Health Research Council of New Zealand. April 2013
  7. Probiotics for preventing urinary tract infections in adults and children.(external link) EM Schwenger, AM Tejani, PS Loewen. Cochrane Systematic Review 2015
  8. Efficacy of probiotics on anxiety-A meta-analysis of randomized controlled trials.(external link) Depress Anxiety. 2018 Oct;35(10):935-945.
  9. A meta-analysis of the use of probiotics to alleviate depressive symptoms.(external link) J Affect Disord. 2018 Mar 1;228:13-19.
  10. Probiotics: sorting the evidence from the myths(external link) The Medical Journal of Australia, 2008

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Credits: Sandra Ponen, Pharmacist, Healthify He Puna Waiora. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Katrina Pace, New Zealand Registered Dietitian

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