Can Probiotics Cause Diarrhea?

Probiotics do not cause diarrhea. On the contrary, one of the most supported advantages of taking probiotics is the prevention of diarrhea. From antibiotic-related diarrhea to traveler’s diarrhea, probiotics have proven to be helpful, not detrimental.

That being said, diarrhea can be a side-effect of probiotics, but not directly caused by them. Rather, probiotic-related diarrhea is caused by one of three things:

  1. The transition stage
  1. Lactose intolerance
  1. A milk allergy

Let’s look at each of these individually and see how they can be prevented.

Diarrhea During the Transition Stage

 Every person’s digestive system responds to the introduction of probiotics according to the state of their unique microbiome and the health of their digestive system.

People with poor digestive health are more likely to experience an unpleasant transition phase because the bacteria currently living in their gut are going to protest the invasion. Likewise, the entire gut environment is going to change, causing temporary side-effects that may indeed include diarrhea.

During the transition stage, it is also common to experience bloating, abdominal discomfort, flatulence, fatigue, and other bowel symptoms. While these side effects can be unpleasant, they are also a sign that the source of probiotic you are taking is of high quality.

Diarrhea Caused by Lactose Intolerance

 Just as discomfort means a probiotic is working, symptoms resulting from lactose intolerance mean a probiotic is not working. This is because probiotics are a common treatment for lactose intolerance; the bacteria actually help digest lactose in foods, relieving many of the symptoms caused by the inability to break down milk sugar.

The issue, however, concerns the manufacturing of probiotic products. Since they are not strictly regulated, manufacturers are not required to state the exact dosage or strain of bacteria used in the product; they are also not required to state their condition. This basically means that some products labeled as “probiotic” can contain ineffective strains- which leaves those with lactose intolerance to battle the dairy singlehandedly.

Lactose intolerance becomes a concern only when the probiotics are paired with dairy, which unfortunately for the affected, happens quite often. Dairy simply happens to be an excellent carrier of probiotics and it’s also cheaper to produce. In theory, that yogurt you picked up is supposed to aid with your digestive issues, including lactose intolerance. But without strict regulation practices and the sheer variety of products, dairy-based probiotics are basically symptomatic landmines whereby you simply must tread lightly and do some brand-based research.

While probiotics have proven effective in treating lactose intolerance over the long run, it goes without saying that there must be probiotics in the product for change to occur. Therefore, someone with lactose intolerance should start out with a non-dairy based probiotic supplement. This will prevent symptoms caused by the by-product as most supplement forms of probiotics are paired only paired with prebiotics (fibers that provide nutrition for probiotic bacteria).

Diarrhea Caused by Milk Allergy

 This is how a milk allergy is different than lactose intolerance: The former is caused by a food allergy and the latter is caused by a digestive issue. An allergy to milk means that the individual has an allergic reaction to the protein found in milk while lactose intolerance means that the individual does not produce enough of the enzyme lactase, which aids in the digestion of the sugar, lactose.

Someone with a milk allergy is going to have a reaction to anything containing milk, so all dairy-based probiotics will cause a negative reaction.

The interesting thing about a milk allergy is precisely its distinction from lactose intolerance. So say that someone takes a dairy-based probiotic and has a reaction. If the probiotics are of high quality, the individual should be unaffected because the bacteria will help break down lactose. However, if the person has an undiagnosed milk allergy, a reaction can occur simply because dairy is present in the product.

Of course we don’t recommend you put your gut on the line for an interesting trial-and-error game. If you’ve had any reaction to dairy products before and want to try a probiotic treatment, the safest bet is to start with a supplement form.

Final Thoughts

 Technically, taking probiotics can cause diarrhea, but only by relation- that is, a person’s specific relation to dairy. Probiotics in themselves should improve (and research shows that they do) diarrhea.

Dairy-based probiotics are the most accessible, but for those with lactose intolerance or milk allergy, the consequences outweigh the benefits.


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