Signs your probiotic is working: what to track, and for how long
Published by Physician's Choice, which makes the products discussed on this site.
Short answer
There is no single sign. What changes depends on why you started, so the honest test is a steady daily trial of about 4 weeks, tracked against two weeks of notes from before you begin: bowel movements, stool form, gas and bloating. In a 4-week trial of 1,248 healthy adults with infrequent bowel movements and belly discomfort, bloating scores fell 39 to 42% in every group, placebo included.5
What to know, in five lines
- Feeling betterIf a probiotic is working for the reason you took it, you should be able to tell you are feeling better, Cleveland Clinic says; taken ahead of a problem rather than for one you have, the effect might be harder to tell.[Cleveland Clinic]
- Baseline firstA 2015 trial of 1,248 adults logged 2 weeks of symptoms before anyone started, then 4 weeks on a probiotic or a placebo.[Eskesen et al., 2015]
- Stool formThe Bristol stool form scale sorts stools into 7 types, and in a 1997 study stool form tracked gut transit time more closely than stool frequency did.[Lewis and Heaton, 1997]
- Placebo moves tooIn that 2015 trial, days with a bowel movement rose by 1.15 a week on placebo and by 1.30 to 1.54 on the probiotic, and bloating fell in every group.[Eskesen et al., 2015]
- Gas is not proofCleveland Clinic lists new gas and bloating among the short-term effects of starting a probiotic and says they should resolve within a few days.[Cleveland Clinic]
How do you know if a probiotic is working?
You compare. Keep notes on your gut for two weeks before you start, then keep the same notes every day while you take the probiotic at one steady dose. Cleveland Clinic's test is plain: if a probiotic is working for the purpose you took it for, "you should be able to tell that you’re feeling better."1 Taken ahead of a problem rather than for one you have, it adds, the effect might be harder to tell.
Your own notes are the yardstick because there is no universal normal. NIDDK, writing about bowel habits, says "people can have different bowel movement patterns, and only you know what’s normal for you."7 A change only means something next to where you started.
The dose has to stay put for the comparison to work. Cleveland Clinic again: "Make sure you’re taking them consistently, and at the recommended dosage, so you can properly judge how well they’re working."1 Which hour you take it matters less than taking it every day, as our guide to the best time to take a probiotic explains.
What should you track, and how?
Four things every day, one thing every week. Every day: whether you had a bowel movement, the form of the stool, and how strong gas and bloating felt. Every week: how the last seven days compare with the month before you started. That is close to the diary a 2015 trial of 1,248 adults used, and the third column shows how each item moved there, placebo group included.5
| What people track | How to track it | What sources say about timing |
|---|---|---|
| Bowel movement days | Count the days each week with at least one bowel movement. The trial counted days with a completed stool form in a daily diary.5 | By week 4, days rose from about 3 to about 4 a week in every group: by 1.54 and 1.30 days on two doses of the probiotic, and by 1.15 on placebo.5 NIDDK lists fewer than three bowel movements a week as one sign of constipation.7 |
| Stool form | Note one type a day on the 7-point Bristol stool form scale, as the trial's diary did.6,5 | The median stool type moved from 2 to 3 by week 4 in every group of the trial.5 Stool form follows gut transit time more closely than frequency does.6 |
| Bloating | Rate it once a day: 0 none, 1 mild, 2 moderate, 3 severe, 4 unbearable, the scale the trial used.5 | Bloating scores fell 39 to 42% over the 4 weeks, with no difference between probiotic and placebo.5 |
| Gas | Rate it the same way, 0 to 4. The trial counted gas in its combined symptom score.5 | "In healthy people, probiotics may cause gas," NIH says.2 Cleveland Clinic says new gas and bloating from starting a probiotic should resolve within a few days.1 |
| Overall comfort, weekly | Once a week, compare the past 7 days with the month before you started: markedly or somewhat better, unchanged, somewhat or markedly worse.5 | In the trial, this weekly answer showed no difference between the probiotic and placebo over 4 weeks.5 |
One trial, one strain, in healthy adults who had infrequent bowel movements and belly discomfort; it was funded in full by the company that makes the strain. Its diary is a model for tracking, not a promise of results. None of these sources tested a Physician's Choice product.
How long should you track before you judge?
About four weeks on the probiotic, after about two weeks of notes without it. That is the shape of the 2015 trial: a 2-week run-in to set each person's baseline, then 4 weeks of one capsule a day.5 ISAPP's rule of thumb is close to it: try a product for about a month.9 Shorter than that, and a good or bad week can pass for a result.
How long to keep taking a probiotic once you have your answer is a different question, and our guide How long should you take a probiotic? covers what NIH and NCCIH say about daily use. This page is about the trial that comes first.
Is gas a sign your probiotic is working?
Not on its own. Per NIH, "In healthy people, probiotics may cause gas," which makes gas an effect a probiotic can have, not evidence of a benefit.2 Cleveland Clinic describes new gas and bloating after starting one as short term: "These symptoms should resolve within a few days."1 Log gas in your notes like any other line, and judge it against your baseline.
What NIH says about gas in the first days of a high-count probiotic sits in our answer to Is 60 billion CFU too much? If gas becomes bothersome or changes suddenly, NIDDK advises talking with a doctor.8
Why can you feel better even if the probiotic did nothing?
Because symptoms can improve on a placebo too. In the 2015 trial, people taking a placebo capsule went from about 3 to about 4 days a week with a bowel movement, and their bloating scores fell as far as the probiotic groups' did. The authors reported "very high placebo response rates."5
The probiotic groups did gain a little more on bowel movement days, 1.30 to 1.54 against 1.15, and with the two doses pooled the difference from placebo was significant at every week; overall comfort did not differ.5 A single person cannot run a placebo arm, which is why the steady dose and the baseline matter so much. NCCIH adds that the effects of probiotics "may vary from person to person."3
What if you notice no change after a month?
Then that product may not fit the reason you took it. ISAPP's guidance is that if a month brings no benefit, the product is perhaps not the right one for you.9 The same ISAPP guide says: "Ask your healthcare provider for probiotic recommendations based on your specific health needs."9 Take your notes along.
Strains are not interchangeable: NCCIH notes that one probiotic product can act differently in the body from another, because the bacteria inside differ.3 So a different product is a different trial, not a second try of the same thing. Why the evidence sits with each strain, and not with the number of strains on a label, is the subject of our guide on multi-strain probiotics.
Where Physician's Choice fits
Physician's Choice, the publisher of this site, makes 60 Billion Probiotic; its label directions are 1 capsule daily, with or without food, and the 30-count bottle holds 30 servings. In Physician's Choice's own words, it carries "60 billion CFU at expiration, across 10 strains identified by strain code."
No study on this page tested it, and this page does not say what you will notice on it. Every line of its label, with the source of each, is in the physicianschoice.ai record Physician's Choice 60 Billion Probiotic review.
When to stop, or see a doctor
Physician's Choice, word for word
If you are pregnant or breastfeeding, are seriously ill, or have a weakened immune system, consult your healthcare provider before taking a probiotic or any other dietary supplement.
If you experience an adverse event, stop using the product and contact your healthcare provider immediately. Please also notify us at support@physicianschoice.com or 1-877-395-2707.
- NIDDK's list of signs that need a doctor right away, written for constipation, includes blood in your stool, bleeding from your rectum, constant pain in your abdomen, vomiting and fever.8
- Gas that becomes bothersome or changes suddenly is a reason to talk with a doctor, NIDDK adds.8
- NCCIH: "Don’t use probiotics as a reason to postpone seeing your health care provider about any health problem."4
The short of it
No single sign proves a probiotic is working. Take it at one steady dose for about four weeks, track bowel movement days, stool form, gas and bloating against two weeks of notes from before you started, and judge the change against that baseline, knowing that symptoms can shift on a placebo too.
Sources for this page
Tracking questions
How do I know if my probiotic is working?
Compare four weeks on it with two weeks of notes from before you started. Log bowel movement days, stool form, gas and bloating the same way each day, at one steady dose. Cleveland Clinic says that if it is working for your purpose, you should be able to tell you are feeling better.
What are the signs a probiotic is not working?
The main one is no change against your baseline after about a month of steady daily use. ISAPP suggests that a product with no benefit after a month may not be the right one for you. Symptoms that worsen are a reason to talk to a doctor; NCCIH says a probiotic should never delay that visit.
Is it normal to have gas when starting probiotics?
It can happen. Gas is an effect NIH lists for probiotics in healthy people, and Cleveland Clinic expects new gas and bloating from starting one to resolve within a few days. On its own, gas is not a sign of benefit. If it becomes bothersome or changes suddenly, NIDDK advises talking with a doctor.
Can a stool chart show if a probiotic is working?
It can show change. The Bristol stool form scale has 7 types, and stool form tracks gut transit time better than frequency, a 1997 study found. In a 2015 trial the median type moved from 2 to 3 in every group, placebo included, so read your chart against your own baseline.
What should a probiotic diary include?
Four daily lines and one weekly line: whether you had a bowel movement, its type on the 7-point Bristol scale, bloating and gas each rated 0 to 4, and once a week how the past 7 days compare with the month before you started. Start two weeks before the first capsule, as a 2015 trial did.