If you are just starting to take a probiotic, you might be wondering how long it will take for it to work. It’s helpful to have realistic expectations so you can avoid throwing in the towel prematurely on an effective probiotic, and avoid wasting money on ineffective probiotic supplements. In this article, we will discuss how long it takes probiotics to work so you can set yourself up for the best results! 

What Are Probiotics?

Probiotics are defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit to the host,” with the “host” being you! In other words, probiotics are beneficial microbes that help support your health. Examples of probiotics include the lactic acid-producing Lactobacillus and Bifidobacteria, and the friendly yeast Saccharomyces boulardii. Probiotics promote health through a multitude of mechanisms, including supporting digestive health, warding off harmful bacteria, inactivating toxins, and supporting a healthy immune system. (Source, Source, Source) 

A growing body of research also indicates that the gut microbiome influences autoimmune disease and that probiotics may help people with autoimmune conditions manage their health. (Source) 

Probiotic supplements provide a targeted way to consume probiotics. However, it may take some time to experience the benefits of probiotics taken this way. The time it takes for a probiotic to work depends on several factors, including why you’re taking it, the type of probiotic, and the dosage, stated in terms of the colony-forming unit (CFU), or number of live probiotic cells per serving.

How Long Does It Take Probiotics to Work?

If you’re starting a new probiotic, you’re likely excited and hopeful that you’ll see results quickly! However, probiotics don’t typically produce immediate positive health results. As you begin taking a new probiotic, having realistic expectations about when you can expect to see results is helpful. 

As mentioned, how long it takes probiotics to work is variable. The tricky part with many probiotic studies is that they only examine symptoms at the beginning and end, not throughout the entire study. For this reason, it usually isn’t possible to conclude when during the study symptom improvement exactly began. However, we can at least glean information about the timeframe over which one could expect to observe health improvements when taking a probiotic.

Next, let’s look at how long it may take probiotics to work for various health conditions. While we won’t detail every condition for which probiotics have been studied, you’ll get an idea of how long it may take to experience benefits from probiotics. Why does it take weeks for probiotics to work in most cases? The time it takes probiotics to work may be related to their mechanisms of action, which include gradually modulating the gut microbiome and reducing inflammation. These are changes that (usually) do not happen overnight. (Source) 

Diarrhea

Probiotics can work quite rapidly for acute diarrhea. Research indicates that Saccharomyces boulardii, a probiotic yeast, can effectively reduce acute diarrhea in children in as little as 3 days. Another probiotic, Bacillus coagulans, has been shown to improve loose stools in 2 to 5 days when taken at a dose of 2 billion microorganisms per day. (Source, Source) 

While probiotics may help quickly for those with acute diarrhea, people struggling with long-term diarrhea, such as diarrhea-predominant IBS, may take longer to see positive results. 

Constipation

A 2015 study published in the British Journal of Nutrition found that healthy adults with constipation (defined as having bowel movements 2 to 4 days per week and abdominal discomfort) receiving Bifidobacterium animalis subspecies lactis over 4 weeks saw significantly improved bowel movement frequency and reduced abdominal discomfort, regardless of whether their doses were 1 billion or 10 billion CFU. However, another study found that a probiotic beverage providing 6.5 billion CFU of Lactobacillus casei Shirota (now known as Lacticaseibacillus casei Shirota) improved constipation over just 2 weeks. These findings suggest taking a probiotic providing 1 billion to 10 billion CFU of probiotic bacteria for at least a couple of weeks may improve constipation. (Source, Source) 

Irritable Bowel Syndrome

Four to 6 weeks of probiotic support may help alleviate irritable bowel syndrome (IBS) symptoms, including diarrhea, constipation (or alternating diarrhea and constipation), abdominal pain, bloating, and gas. For example, 4 weeks of supplementation with a 200 billion CFU probiotic containing Lactobacillus and Bifidobacteria significantly improved bloating in individuals with IBS. In another study, 6 weeks of supplementation with Lactobacillus and Bifidobacteria strains at a dose of 10 billion CFU improved abdominal pain, distension, stool consistency, and quality of life in people with IBS; however, some participants noticed improvements as soon as 3 weeks into the probiotic trial. (Source, Source)

Depression

A growing body of research indicates a strong connection between the gut and mental health, suggesting probiotics may be useful tools for supporting mental well-being. A pilot study of patients with IBS found that 10 weeks of supplementation with 10 billion CFU of Bifidobacterium longum significantly reduced depression but not anxiety. A randomized clinical trial showed that 4 weeks of supplementation with the probiotic Bifidobacterium breve CCFM1025 at a dose of 10 billion CFU per day improved depression symptoms in people with major depressive disorder. (Source, Source) 

Together, these studies suggest that probiotic supplementation may need to be implemented for at least a month, if not several months, to improve depression.

Lactose Intolerance

Probiotics may improve lactose intolerance — an inability to fully digest a sugar called lactose found in dairy products — but the effect is gradual. For example, a meta-analysis of studies found that probiotic ingestion reduced symptoms of lactose intolerance in adults, with an average period of approximately 26 days required to see effects. The studies included in the meta-analysis utilized a wide range of probiotic strains at varying dosages, including Lactobacillus acidophilus, Bifidobacterium strains, Limosilactobacillus reuteri (formerly known as Lactobacillus reuteri), Lacticaseibacillus casei Shirota (formerly known as Lactobacillus casei Shirota), Streptococcus thermophilus, and Lactobacillus delbrueckii spp. Bulgaricus. (Source)  

Autoimmune Disease

Probiotics are increasingly being examined for their potential immune health benefits in people with autoimmune diseases. In a study published in the International Journal of Rheumatic Diseases, 6 billion CFU total of combined Lactobacillus and Bifidobacterium strains given over 8 weeks improved symptom scores and inflammatory markers in people with rheumatoid arthritis. In another study of people with ulcerative colitis, 8 weeks of supplementation with 200 billion to 300 billion CFU of Bifidobacterium longum significantly reduced symptoms and intestinal inflammation over 8 weeks. (Source, Source) 

Atopic Dermatitis

A growing body of research indicates that gut and skin health are connected, and some studies suggest that probiotics may improve skin health by altering the gut microbiome. A randomized double-blind, placebo-controlled study of children found that 10 billion CFU of Lacticaseibacillus rhamnosus GG given over 12 weeks significantly improved atopic dermatitis, a condition in which the skin becomes dry, itchy, and inflamed. Another study found that 16 weeks of probiotic supplementation at a dose of 1 billion CFU improved atopic dermatitis in adults. Based on the available research, it seems reasonable to expect that a couple of months may be required to observe probiotic-induced improvements in atopic dermatitis. (Source, Source)

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Tips for Effective Probiotic Use

Setting realistic expectations about when to expect results from a probiotic is a smart idea. However, there are steps you can take to help ensure effective probiotic use.

• Choose a high-quality probiotic from a reputable brand. 
• Look for a probiotic that includes well-studied probiotic strains at an optimal dose. Lactobacillus, Bifidobacteria, and Saccharomyces boulardii are the most thoroughly studied strains of probiotics, with abundant evidence demonstrating their health benefits. While there is no consensus on the optimal CFU count for probiotic supplements, many studies involve probiotic doses of at least 1 billion CFU, with multiple studies providing 10 billion CFU or more. (Source, Source) 
• Make sure you store your probiotic supplement correctly. Many probiotics should be stored in the refrigerator, while some can be stored at room temperature. Read the label on your supplement to confirm where it should be stored. In any case, you should avoid exposing your probiotics to heat and humidity as these environmental factors may degrade them. (Source) 
• It’s also important to make sure you take your probiotic consistently and at an optimal time of day, depending on whether or not you’re taking it with food.  (Source)

The Bottom Line

Based on the research, probiotics may take several weeks to work if you’re taking them for a chronic health condition such as mood, skin, or digestive issues. This timeframe will help you manage your expectations when you start a new probiotic and avoid throwing in the towel prematurely before the probiotics have had sufficient time to take effect. On the other hand, specific probiotics, such as Saccharomyces boulardii and Bacillus coagulans, may help alleviate acute diarrhea within just a few days. 

Of course, you should consult your health care provider before starting a probiotic to determine whether probiotics are appropriate for you, and to select one suited to your needs.

Probiotics offer powerful health benefits, provided you take a high-quality probiotic at the appropriate dosage and for an optimal length of time. If you need help managing your health care, including determining whether probiotics are right for you, WellTheory’s Care Team can help! Our team can provide personalized guidance, helping you find relief from autoimmune symptoms so you can feel your best and confidently manage your health.