Probiotics may be used to help manage a variety of conditions and symptoms. Depending on what you’re taking probiotics for, you may see symptom improvements anywhere between a few days to a few months.

Probiotics are so popular today that global sales are over $40 billion, and only projected to grow.

Maybe you’ve tried a probiotic in the past. Did you wonder how long you needed to take it? Or if it even worked? With so many products to choose from, it can be overwhelming to find the right one.

How long should it take your probiotic to work? The answer depends on why you’re taking it, what type you’re taking, and how much you’re taking.

Probiotics are live microbes (yeast or bacteria) that provide health benefits when taken in the right amounts.

According to an expert panel of the International Scientific Association for Probiotics and Prebiotics (ISAPP), manufacturers need to use more evidence-based studies in order to claim health benefits.

Unfortunately, today there are plenty of products on the market making claims with no proof they work.

The Food and Drug Administration (FDA) doesn’t review the quality of probiotics since they’re sold as either dietary supplements, fermented foods, or in food additives.

Let’s take a closer look at how to choose the right probiotic and understand how they work, so the next time you want to try one, you’ll pick the best probiotic supplement for you.

Probiotic doses are listed as colony forming units (CFUs), which means the number of live strains in each dose.

Different brands will have different suggested doses and uses, so it’s important to understand the information listed.

Recent research found that the type of microbe strain, health condition, product formula, dose, and the quality of the product are all important for effectiveness.

The condition or symptom you’re trying to treat can affect how the probiotic works and when you’ll see results. If you’re taking a probiotic for general gut or immune health, you’ll need to take it awhile to see results.

On the other hand, if you’re taking a probiotic for relief from diarrhea, you may see faster results.

For example, research from 2010 has shown that, when used in combination with rehydration therapy, treatment with probiotics can reduce the duration and frequency of infectious diarrhea in as little as 2 days.

Another study demonstrated that people who consumed a high-dose probiotic drink containing Lactobacillus paracasei, Lactobacillus casei, and Lactobacillus fermentium for 12 weeks experienced significantly less upper respiratory infections and flu-like symptoms compared to a placebo group.

Plus, it was shown that the probiotic drink boosted the immune system of the participants by increasing levels of antibodies including sIgA in the gut after 12 weeks.

Yet another study from 2011 found that people with irritable bowel syndrome (IBS) who supplemented with Saccharomyces boulardii for 4 weeks experienced significant improvements in IBS-related symptoms compared to a control group.

Depending on what you’re taking probiotics for, you may see symptom improvements anywhere between a few days to a few months.

Probiotics don’t work for everyone. Your unique gene makeup, age, health, bacteria you already have in your body, and diet all affect how probiotics work.

Here are a few more reasons why a probiotic may not work:

why probiotics don’t always work
  • The dose isn’t correct (too few CFU).
  • You aren’t taking it correctly (with food versus on an empty stomach). Read the label and follow the product directions on how to take it.
  • It’s the wrong strain. Not all strains work for every symptom. Find the right match based on proven studies.
  • The product quality is poor (live cultures). One of the biggest challenges with probiotics is their fragile nature. They must survive the process of manufacturing, storage, and your stomach acid in order to be effective in your intestines.
  • They were stored improperly. Humidity, heat, and light can also affect probiotics negatively. Some may need to be refrigerated.

Choosing the right probiotic depends on why you’re taking it. Effectiveness is specific to the strain and the condition.

Probiotics can be found in foods such as yogurt, or in dietary supplements, with various popular strains.

Although there are many claims made by probiotic products, there’s now reliable, evidence-based support that certain probiotics — like Lactobacillus, Bifidobacterium (bacteria), and Saccharomyces boulardii (yeast) — are generally safe and helpful in specific conditions.

probiotics may be most effective for these conditions

A new review also found probiotics to be helpful in healthy people to maintain gut, vaginal, and immune health.

The biggest points to keep in mind for success are the 3 R’s:

  • Right condition. Probiotics don’t work for every illness, so it’s important to match the symptom to the strain.
  • Right microbe. The strain matters. (For example, Lactobacillus acidophilus versus Bifidobacterium longum) For best results, choose based on the evidence supporting the symptom. Consult a doctor before starting a supplement.
  • Right dose (CFU). The dose depends on the health condition or symptom you’re trying to manage. On average, a dose of 5 billion CFUs or higher was found to be more effective than lower doses for treating gastrointestinal conditions. Doses vary by brand. Many brands have multiple strains so be sure to read the label carefully. Doses are also different for children and adults.

The most important way to make sure the probiotic you choose will work is to find a reputable brand and follow the label directions suggested on how to take it. Each brand will have specific information based on the product.

Manufacturers are constantly trying to improve probiotic effectiveness by using different methods such as microencapsulation to protect probiotics from the environment, increasing chances of survival and potency.

tips for effective probiotic use

For a probiotic to work for you, it should be:

  • Good quality (live cultures). Choose one that shows proof of effectiveness.
  • Stored correctly. Read labels and store as the label states (refrigeration, room temperature, etc.).
  • Taken as directed. Read labels and take as suggested (before meals, at bedtime, etc.).
  • Able to survive in the body. The probiotic must be able to survive the trip through stomach acid and bile and colonize your gut.
  • Safe for you. Read the label and note added ingredients. Watch out for added fillers and binders which might cause reactions.

A typical label will have the name of the specific probiotic (such as Lactobacillus acidophilus), the dose in CFU, an expiration date, and instructions for use and storage.

The expiration date is important because it should have the “use by date,” which is how long the product will have live cultures.

Avoid products that list expiration as “time of manufacture.” The cultures may not be active or be less than listed by the time you buy it.

With so many probiotic products on the market today, it can be confusing to pick the best one for you.

The World Gastroenterology Organization Global Guidelines has compiled a comprehensive list of evidence-based conditions that probiotics can help. The list includes specific strains of probiotics and recommended doses.

Read the label carefully to find the right strain, dose, how to take it, expiration date, and how to store. Here’s an example from ISAPP of what to look for in a label.

For certain people, probiotics are not the right choice. Be sure to discuss taking any supplements with your doctor first. You should also discuss concerns about side effects or interactions with other medications you’re currently taking.