Medically Reviewed

Probiotics Side Effects: Should You Be Worried?

Like most supplements, probiotics do come with concern of side effects. While side effects are rare and mild, a discussion of these effects is still warranted.

Probiotic Side Effects

Your body naturally contains a variety of bacteria and other microorganisms. As one of the fastest growing supplements in terms of popularity, the benefits of probiotics are quickly being revealed. But there may be some side effects that accompany these benefits. For most people, these side effects are minor (if they occur at all). Regardless, it is important to discuss the side effects that a person may experience after taking a probiotic.

How do probiotics work?

As mentioned briefly above, probiotics replenish the good bacteria in your body. Your body thrives when it is in balance.

Adding good bacteria to your system can promote a variety of health benefits. One of the most important benefits is the immune system support that good bacteria provide. About 70% of the immune system lives in the gut. This provides probiotics a way to communicate with and impact the immune system. Other benefits include improved bowel movements, food digestion, and absorption. One recent study suggests that probiotics can support digestive absorption by producing short chain fatty acids. Your gut bacteria ferments fiber and makes short chain fatty acids. This is important to support your gut and bowel health. Overall there are many ways that probiotics can support your immune and digestive system.

H3: How effective are probiotics?


As probiotic research has expanded, so has the public’s interest in taking probiotics. Does the attention that probiotics are getting match their efficacy? Luckily, the answer is yes. These benefits include immune Support, improvement in bowel movement patterns and fecal microflora, normalization in bowel movements, and reduction in loose stools as a result of antibiotic use.

The benefits of probiotics are broad and researchers are continually uncovering more positive outcomes associated with taking a probiotic. One study tested the safety and efficacy of a probiotic yogurt supplemented with B. lactis (BB-12) on healthy volunteers over a 7-week period. The participants were divided into 2 groups depending on their bowel movement tendencies. Those who experienced fewer bowel movements noticed improvements in frequency and stool analysis revealed an increase in Bifidobacteria as well.

The efficacy of probiotics depends on several factors including the strains used, dosage, and frequency of use. Like most things in life, consistency is key so continued use of probiotics over a period of time may be more promising for benefits.

What are the most common types of probiotic bacteria?

Probiotics are made up of different strains of good bacteria. Probiotics are not all created equal. It is important to take a high quality product that delivers the microorganisms that are necessary to maintain good health. In recent years, researchers have focused heavily on a few strains of microorganisms in probiotics.

Some probiotic supplements combine multiple strains to deliver more possible benefits. Other probiotic supplements may contain a single strain to target a specific health outcome. The most well researched probiotic strains fall within the Lactobacillus and Bifidobacteria family. Both Lactobacillus and Bifidobacteria strains are commonly found in the digestive system and the genitourinary tract. Some probiotics are shelf stable whereas others need to be refrigerated. Looking at the label will let you know how to properly store the probiotic to maintain optimal quality. Your specific health goal or desired outcome will likely dictate which type of probiotic is best for you.

What should I expect when I start taking probiotics?

Before taking a probiotic, you should speak with your physician about the best way to begin. If you may benefit from a probiotic, your physician may recommend starting with bacteria-containing foods before starting a probiotic supplement. For example, foods such as yogurt and kefir contain good bacteria. Your physician may recommend that you start with a smaller dose (lower CFUs) when first starting out. Some of the most common initial experiences include temporary stomach and bowel changes (e.g. irregular bowel movements) since the bacteria directly impact your digestive and metabolic systems. Some people report bloating or softer stools when starting a new probiotic which are both normal due to the changes happening in your gut biome.


Are there side effects to taking probiotics?

Like over-the-counter products, probiotics may have some side effects. Luckily, most people do not experience them at all or if they do, not for long. Overall, probiotics are normally considered to be safe because they contain strains of microbes that are already present within our bodies. If you continue to experience digestive discomfort over an extended period of time then you may want to consider a lower potency (lower CFU) or different strain. Before beginning a probiotic, you should speak with your physician. They will be able to discuss the side effects that you may experience in greater detail and recommend a specific probiotic if a probiotic is right for you.

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