Can probiotics cause constipation? What sources say and what to do

Key facts

• A large dose, or a gut that tends to be sensitive, makes short-term constipation from a new probiotic more likely. [Cleveland Clinic]
• Constipation can mean fewer than three bowel movements a week, hard, dry or lumpy stools, stools that are hard to pass, or a sense that not all stool has passed. [NIDDK]
• Bowel habits differ from person to person, and "only you know what's normal for you." [NIDDK]
• Iron supplements and antacids that contain aluminum and calcium are among the products that can make constipation worse. [NIDDK]
• When constipated, drink 8 to 10 cups (2 to 2.5 L) of liquids a day, particularly water. [MedlinePlus]
• Constipation with blood in your stool, constant belly pain, vomiting or fever needs a doctor right away. [NIDDK]

What do Cleveland Clinic and NIH say about probiotics and constipation?

That it can happen early on, and that probiotic side effects tend to be mild. Under the question "Can probiotics cause diarrhea, constipation or stomach pain?", Cleveland Clinic answers that

"in the short term, it's possible that introducing new probiotics could trigger similar symptoms"

Cleveland Clinic, Probiotics

The same page says the odds go up with a large dose, or when your gut tends to be sensitive in general. In wording Physician's Choice has approved for its pages: According to the NIH Office of Dietary Supplements, probiotics are generally well tolerated by healthy people, though they may cause mild digestive symptoms, such as gas. Probiotics may not be appropriate for everyone, particularly people who are seriously ill or have weakened immune systems. Talk with your healthcare provider before use.

Two things the sources leave open. Cleveland Clinic explains why a new probiotic can loosen stools or add gas, but offers no reason for constipation. And no one has counted how often it happens: NCCIH notes that few studies have examined probiotic safety in detail, so solid figures on how often side effects occur are missing.

How long does constipation from a probiotic last?

No source we checked gives a number of days. Cleveland Clinic says only "in the short term," and NIDDK says constipation of any cause "may last for a short or long time."

One line is easy to misread. Cleveland Clinic does give a time for one side effect: extra gas and bloating "should resolve within a few days." That time frame is about gas and bloating; the page gives none for constipation, and this page does not borrow it.

So go by what you notice, not the calendar. MedlinePlus says to contact your provider if you have not had a bowel movement in 3 days, and NIDDK says to see a doctor when symptoms do not go away with self-care. Physician's Choice puts it this way: If constipation does not get better with changes to what you eat and drink, talk to your doctor.

Looser stools are the other common change; can probiotics cause diarrhea or loose stools? covers them, and gas in the first weeks of a probiotic covers gas. Gas that smells stronger is a separate question, taken up in smelly gas from probiotics. What longer trials measured on stool frequency in adults who were already constipated is in do probiotics make you poop?

Could something else be behind it?

Look at the rest of your week first. NIDDK lists many causes of constipation, and several of them tend to change at the same time as a new supplement.

Other pills. NIDDK names iron supplements, antacids that contain aluminum and calcium, and several prescription medicines among the products that can make constipation worse. MedlinePlus adds that some medicines, and even some vitamins, can constipate you.

Your routine. Bowel movements can change when you travel, change your medicines, change how much and what you eat, or ignore the urge to go, NIDDK says. Too little fiber, too few liquids and too little physical activity are on its list as well.

If a probiotic, an iron pill and a new eating plan all started in the same week, the probiotic may not be the cause. NIDDK's advice is to talk with your doctor if you think a supplement is behind it:

"Don't change or stop any medicine or supplement without talking with a health care professional."

NIDDK, on constipation and supplements

What helps if you feel constipated after starting a probiotic?

The everyday steps for any constipation, with the probiotic kept at the label amount while you try them.

1. Check the amount. Cleveland Clinic links short-term stomach symptoms to large doses and says to take a probiotic as recommended on the label.
2. Drink more. MedlinePlus suggests 8 to 10 cups (2 to 2.5 L) of liquids a day, particularly water, while you are constipated.
3. Add fiber slowly. NIDDK says to add fiber a little at a time so your body gets used to it, and MedlinePlus warns that more fiber can cause bloating and gas.
4. Move. Walk, swim or do something active at least 3 or 4 times a week, MedlinePlus says.
5. Keep a routine. Trying for a bowel movement 15 to 45 minutes after breakfast may help, NIDDK says, because eating helps your colon move stool.
6. Ask before a laxative. MedlinePlus says to take a laxative only as often as your provider recommends, and that pregnant or breastfeeding women and children under 6 should not take laxatives without a provider's advice.

Magnesium, an ingredient in some laxatives that is also sold as a supplement, has its own upper limit; see supplements for bloating.