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When and for how long should you take probiotics?

By Published 8 min read

Should probiotics be taken in the morning or in the evening? Before, with or after food? And how long should you keep going? If you search for it, you get conflicting answers, and most of them do not refer to any research.

Here is what the research shows, and where it has no answer.

Short answer

  • Timing: We have not found a single trial in humans that has tested whether morning, evening, before or after food makes a difference. In laboratory models of the stomach, more bacteria survive when they are taken with or just before a meal.
  • Duration: In the IBS trials, participants took the product for 4 to 8 weeks. The Danish IBS guideline says: try them for 4 to 8 weeks, then take a break or stop.
  • When you stop: The bacteria do not settle in the gut. Most are gone from the stool within a week or two.
  • Storage: Heat and humidity kill the bacteria. Follow the pack, and store them somewhere cool and dry.

When in the day should you take probiotics?

Nobody knows. We have not found any trials in humans that have compared morning with evening, or before, with and after food, when it comes to the stomach. What exists are laboratory experiments that imitate the stomach and the duodenum.

The most practical advice is therefore to follow the directions on the pack and take them at the same time every day, so you remember. Several trials have done exactly that. In a Swedish trial on colds, for example, participants were asked to take the powder with breakfast if possible [5].

Before, with or after food?

The study that most advice is based on is from 2011. In a model of the stomach and duodenum, the bacteria in a capsule product survived best when it was given together with a meal or 30 minutes before. Given 30 minutes after the meal, they did not survive in very large numbers. A meal with a little fat, porridge with milk, protected them best, while water and apple juice were worst [1]. The study was carried out by the company that makes the product.

Two newer models point the same way when it comes to food:

  • With eight products, the bacteria lost the fewest with porridge and the most with juice [2].
  • In a model with Lacticaseibacillus rhamnosus GG, the bacteria did better both with and after a meal than on an empty stomach [3]. So whether "after food" is bad is unclear.

If the capsule is acid-resistant (a so-called enteric capsule), the stomach matters less. That too has only been shown in the laboratory [4]. And the yeast Saccharomyces boulardii was not affected by the meal at all in the first model [1].

All of this is about how many bacteria get through alive in a model. It says nothing about whether they work better in a real stomach.

How quickly do probiotics work?

It depends on what they are used for:

  • IBS: Most trials lasted 4 to 8 weeks, and the effect was measured at the end. Trials of 8 weeks or more did not show a greater effect than the shorter ones [6]. Read more in the article on probiotics and IBS.
  • Antibiotics: The protection against diarrhoea is seen during the course. It was greatest when the bacteria were started within the first two days of the course [7][8]. See the article on probiotics after antibiotics.
  • Colic: In the first positive trial with L. reuteri DSM 17938, more babies than in the placebo group had already halved their crying time after one week (20 against 8). The trials lasted 3 to 4 weeks [9]. See the article on probiotics for babies.

How long should you take probiotics?

The 2026 Danish IBS guideline gives this advice to patients: "If you try probiotics, try them for 4-8 weeks and then take a break or stop again. If they work, you will probably need to continue the treatment to get a lasting effect" [10].

The British guideline says up to 12 weeks, the Canadian one e.g. a month. What they have in common is that you set a time limit and stop if it does not help.

For antibiotics, the trials gave the bacteria during the course and sometimes up to four weeks after. It has not been shown that continuing after the course helps more [8]. For patients at high risk of the gut infection C. difficile, the Danish doctors' handbook (Lægehåndbogen) on sundhed.dk mentions the yeast S. boulardii during the course and for two weeks after [11]. That is a decision for the doctor.

What happens when you stop?

The bacteria do not settle in the gut. When researchers gave healthy people L. rhamnosus GG, it could be found in the stool of 87% four days after they stopped, but in only 33% after seven days [12]. A few keep a strain for months. In one trial this applied to 30% [13], but it is the exception.

That is also what sundhed.dk says: "Nor do the probiotic bacteria colonise the gut permanently" [14]. That is why the Danish guideline says that an effect probably requires you to keep going.

Can you take probiotics every day for a long time?

For healthy people with a normal immune system, short-term use is considered safe [15]. But what happens after many years of daily use has been poorly studied. A large American review concluded that the long-term effects are "largely unknown" [15], and an international expert panel wrote in 2023 that trials rarely follow safety over a long period [16].

Nor is there good evidence that healthy people get any extra benefit from taking probiotics every day for years [17]. If you belong to a risk group, read the article on probiotic side effects.

Should probiotics be kept in the fridge?

Follow the pack. Heat and humidity kill the bacteria.

In a Czech study from 2026, ten supplements were stored for a year at room temperature, in the fridge and in the freezer. At room temperature, half of them no longer had measurable live bacteria after 6 to 12 months. At the expiry date, 6 of the 10 still matched the pack when they had been kept in the fridge, but only 3 of 10 at room temperature [18]. Two of the products kept well at every temperature, so some can easily stay in the cupboard.

In Denmark, the number of bacteria on a food supplement must be accurate for the whole shelf life, not just on the day it was made [19]. Read more about what the numbers mean in the article on CFU and bacterial strains.

How long should you leave between antibiotics and probiotics?

Lægehåndbogen says of Idoform, a probiotic sold in Denmark as a natural medicine, that it should be taken 3 hours before or after antibiotics [20]. Other products may have different directions. Read more in the article on probiotics after antibiotics.

My experience

I take probiotics myself as the first thing in the morning, and after that I do yoga and stretching. I have taken them for about a year and take a break every other month. The powder is kept in the kitchen cupboard, away from humidity and heat.

If you want to follow what the research points to, take them with a meal or just before one instead, for example with breakfast, ideally a meal with a little fat such as porridge with milk. That is when most bacteria made it through the stomach in the laboratory models above. I don't do that myself at the moment. The morning routine with yoga and stretching has become a fixed part of my day, and I find that it helps with my bloating. Read more about my story.

This is one person's experience. Personal experience is not evidence that something works. What the trials show is above.

The bottom line

  • No trials in humans have tested whether it matters what time of day you take probiotics.
  • In laboratory models, more bacteria survive with or just before a meal than with water or juice.
  • The Danish IBS guideline says: try them for 4 to 8 weeks, then take a break or stop.
  • The bacteria disappear from the gut within days to weeks when you stop.
  • Heat and humidity kill the bacteria, so store them as directed on the pack.

Sources

  1. Tompkins TA et al. The impact of meals on a probiotic during transit through a model of the human upper gastrointestinal tract. Benef Microbes. 2011. PMID 22146689
  2. Treven P et al. The Effect of Food Matrix Taken with Probiotics on the Survival of Commercial Probiotics in Simulation of Gastrointestinal Digestion. Foods. 2024. PMID 39410170
  3. Wang J et al. Effect of Food Matrix and Administration Timing on the Survival of Lacticaseibacillus rhamnosus GG During In Vitro Gastrointestinal Digestion. Foods. 2025. PMID 40941193
  4. Marzorati M et al. Comparison of protection and release behavior of different capsule polymer combinations based on L. acidophilus survivability and function and caffeine release. Int J Pharm. 2021. PMID 34384885
  5. Ahrén IL et al. Fewer Community-Acquired Colds with Daily Consumption of Lactiplantibacillus plantarum HEAL9 and Lacticaseibacillus paracasei 8700:2. A Randomized, Placebo-Controlled Clinical Trial. J Nutr. 2021. PMID 33296464
  6. Li B et al. Efficacy and Safety of Probiotics in Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis. Front Pharmacol. 2020. PMID 32317962
  7. Shen NT et al. Timely Use of Probiotics in Hospitalized Adults Prevents Clostridium difficile Infection: A Systematic Review With Meta-Regression Analysis. Gastroenterology. 2017. PMID 28192108
  8. Liao W et al. Probiotics for the Prevention of Antibiotic-associated Diarrhea in Adults: A Meta-Analysis of Randomized Placebo-Controlled Trials. J Clin Gastroenterol. 2021. PMID 33234881
  9. Savino F et al. Lactobacillus reuteri DSM 17938 in infantile colic: a randomized, double-blind, placebo-controlled trial. Pediatrics. 2010. PMID 20713478
  10. Dansk Selskab for Gastroenterologi og Hepatologi. Colon irritabile: Diagnostik og behandling. National guideline. 2026. dsgh.dk
  11. Sundhed.dk. Antibiotika-associeret diarré. Lægehåndbogen. Updated 2024. sundhed.dk
  12. Goldin BR et al. Survival of Lactobacillus species (strain GG) in human gastrointestinal tract. Dig Dis Sci. 1992. PMID 1728516
  13. Maldonado-Gómez MX et al. Stable Engraftment of Bifidobacterium longum AH1206 in the Human Gut Depends on Individualized Features of the Resident Microbiome. Cell Host Microbe. 2016. PMID 27693307
  14. Sundhed.dk. Probiotika. Patienthåndbogen. Updated 2024. sundhed.dk
  15. Hempel S et al. Safety of probiotics used to reduce risk and prevent or treat disease. Evid Rep Technol Assess (Full Rep). 2011. PMID 23126627
  16. Merenstein D et al. Emerging issues in probiotic safety: 2023 perspectives. Gut Microbes. 2023. PMID 36919522
  17. Merenstein DJ et al. Is There Evidence to Support Probiotic Use for Healthy People? Adv Nutr. 2024. PMID 38977065
  18. Brousilova T et al. Storage temperature as a determinant of probiotic long-term stability in commercial dietary supplements. Front Nutr. 2026. PMID 42824401
  19. Fødevarestyrelsen. Vejledning om kosttilskud. VEJ nr. 9488 af 28/06/2024, section 6.2.2.2. retsinformation.dk
  20. Sundhed.dk. Mælkesyrebakterier til tarmen (Idoform). Lægehåndbogen, DLI medicin. sundhed.dk

This article is general information and not medical advice.