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10th February, 20213 min read

How long do probiotics take to work? Your probiotics questions answered

Medical reviewer:Dr Adiele Hoffman
Author:Caroline Bodian
Last reviewed: 08/02/2021
Medically reviewed

All of Healthily's articles undergo medical safety checks to verify that the information is medically safe. View more details in our safety page, or read our editorial policy.

Tummy trouble can sometimes be a sign of an imbalance of bacteria in your gut. Research suggests that probiotics, also called ‘good’ or ‘friendly’ bacteria, may be helpful in easing discomfort and restoring gut balance. There's also evidence that probiotics could help prevent diarrhoea when taking antibiotics, and might ease the symptoms of irritable bowel syndrome (IBS).

Probiotics are live bacteria that are often added to or found naturally in foods like yoghurt or taken as a supplement. Not all probiotics are the same and some strains of bacteria are specific to easing the symptoms of certain conditions. For example, the most common probiotics used to treat IBS come from bacteria strains called Lactobacilli and Bifidobacteria.

Probiotics are classed as a food rather than medicine, which means they don’t go through the same strict testing that medicines do. Probiotics should be safe for you to take if you’re generally healthy and have a good immune system – if you’re unsure, speak to your doctor first.

How long do probiotics take to work?

In order to experience the potential benefits of probiotics, you usually need to take them regularly, in the right amounts and over a period of at least 4 weeks. Stomach acid makes it hard for probiotics to survive, so taking them regularly over a long period of time makes it more likely they’ll survive and have a positive effect.

Which foods contain probiotics?

Probiotics are often taken as a supplement, but they’re also added to or found naturally in some foods, including:

  • some yoghurts: the packaging must say that live cultures are included
  • kefir: a fermented milk drink
  • kombucha: a fermented sweet tea
  • kimchi: a spicy, fermented cabbage dish

What’s the difference between a prebiotic and probiotic?

Prebiotics are like food for ‘good’ bacteria. They promote healthy bacteria and can be found in foods like garlic, onions, leeks, asparagus and artichokes.

Some supplements contain a combination of probiotics and prebiotics – these are called synbiotics.

Are probiotics safe for everyone?

While research suggests that probiotics could be helpful for IBS, diarrhoea, constipation and ulcerative colitis, they may not be suitable for everyone.

For some, there’s a very small risk of sepsis. For example, if you have a compromised immune system or have just had surgery, taking probiotics can pose a risk. Conditions that can weaken your immune system include cancer and HIV. Speak to your doctor if you’re unsure whether probiotics are right for you.

Side effects of probiotics can include bloating or wind when you start taking them. This should go away after a few days, although you may need to reduce the dose if these symptoms persist. If side effects continue, stop taking the probiotics or speak to your doctor.

Key points

  • probiotics may be helpful in easing tummy discomfort and restoring gut balance
  • probiotics are found in some foods, like yoghurt and kimchi, or are taken as a supplement
  • probiotics are classed as food, not medicine
  • you need to take the right dose of probiotics for about 4 weeks to experience any potential benefits
  • probiotics may not be suitable for people with a weakened immune system
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