Most people take probiotics with no problems beyond a little extra gas. But probiotics are live microbes, and for some people the risks are real. Here is how to tell normal from not.
Written by Vita Globe Editorial Team | Reviewed against NIH guidance, FDA safety communications and peer-reviewed research
What are the side effects of probiotics?
For most healthy people, side effects are minor and short-lived, usually gas or other mild digestive symptoms[1]. Serious problems are rare but real: bloodstream infections have been linked to probiotics, mostly in people who were severely ill or immunocompromised[1]. People with weakened immune systems, critical illness or central venous catheters face higher risk[2], and the FDA warns against probiotics in premature infants[3].
Caveat: Probiotic trials often report side effects inconsistently, so the true rate of adverse events is not precisely known[2].
Sources: NIH ODS · Doron & Snydman, 2015 · FDA safety alert · Verified 2026-09-27
IN THIS ARTICLE
What side effects are normal?
The NIH Office of Dietary Supplements describes probiotic side effects as usually minor, consisting of self-limited digestive symptoms such as gas[1]. In a Cochrane review of 33 pediatric trials, adverse events occurred in 4% of children given probiotics and 6% of those in control groups, and included rash, nausea, gas, bloating and constipation[4].
- Gas or flatulence
- Mild bloating
- Changes in stool consistency
- Occasional nausea
These are usually temporary. If they do not settle, stop and reassess.
What are the rare but serious risks?
Researchers have identified several potential harms from probiotics: systemic infections, harmful metabolic activity, excessive immune stimulation in susceptible people, gene transfer between microbes, and gastrointestinal side effects[2]. The most concrete concern is infection. The NIH notes that probiotics have been linked to bacteremia (bacteria in the blood), fungemia (yeast in the blood) and other infections, mostly in severely ill or immunocompromised patients[1].
Product quality is another issue. NCCIH notes that some probiotic products have been reported to contain microorganisms other than those listed on the label, which could pose serious risks[5]. Buying from a brand that lists its strains and tests its products matters.
Who should talk to a doctor before taking probiotics?
- People with weakened immune systems, whether from a medical condition or from medicines that suppress immunity[2][5].
- People who are critically ill or hospitalized[2].
- People with central venous catheters or similar devices[2].
- Premature infants. The FDA warns that preterm infants given probiotics are at risk of invasive, potentially fatal disease[3].
- Anyone pregnant, breastfeeding, taking prescription medicine, or managing a medical condition.
For more on children specifically, see Probiotics for Kids: Are They Safe?. For pregnancy, see Probiotics for Women: What the Research Supports.
When should you stop taking a probiotic?
Stop and contact a clinician if you notice:
- Fever, chills or feeling generally unwell after starting
- Severe or worsening abdominal pain, diarrhea or vomiting
- Signs of an allergic reaction such as hives, swelling or trouble breathing (seek emergency care)
- Digestive side effects that last more than a couple of weeks
For people with serious illness or weakened immunity, a fever after starting a probiotic should always be reported to their care team promptly.
How can you lower the chance of side effects?
- Follow the label. Taking more than directed has not been shown to add benefit, and effects depend on the strain[6].
- Check the full ingredient list for allergens and sweeteners, not just the probiotic blend.
- Introduce one new supplement at a time so you can tell what is causing a reaction.
- Store it properly and use it before the date; see How to Store Probiotic Gummies.
Researchers have also pointed out that many trials report safety data poorly, including a large JAMA meta-analysis on antibiotic-associated diarrhea that noted limited adverse-event reporting[7]. "Generally safe" should be read as "generally safe for healthy people."
The honest summary
- Mild gas and digestive changes are the most common side effects and usually pass[1].
- Serious infections are rare and mostly affect severely ill or immunocompromised people[1][2].
- Premature infants should not be given probiotics outside medical guidance[3].
- If you have a serious condition or weakened immunity, ask your doctor first.
Our option
Vita Globe Super Probiotic Gummies – Pouch
Super Probiotic Gummies contain a live probiotic blend that includes Bacillus coagulans and Bifidobacterium lactis. The suggested use is 2 gummies once daily, and each resealable pouch holds 14 gummies. They are gluten-free, non-GMO and tested by an independent third-party lab. If you have a medical condition or a weakened immune system, check with your healthcare provider before starting.
Frequently asked questions
How long do probiotic side effects last?
Mild digestive effects like gas are usually self-limited[1]. If they persist or get worse, stop and talk to a clinician.
Can probiotics cause diarrhea?
Changes in stool consistency are possible, especially at first. Severe or persistent diarrhea is not normal and should be checked by a clinician.
Are probiotics safe for people with weakened immune systems?
People who are immunocompromised face a higher risk of rare but serious infections from probiotics[2][1]. They should only use probiotics under medical guidance.
Can you be allergic to a probiotic supplement?
Allergic reactions can be caused by any ingredient, including allergens, colors or sweeteners in the gummy itself. Read the full ingredient list, and seek emergency care for signs of a severe allergic reaction.
Sources
- Office of Dietary Supplements, National Institutes of Health. Probiotics: Fact Sheet for Health Professionals. Updated March 25, 2025. ods.od.nih.gov
- Doron S, Snydman DR. Risk and safety of probiotics. Clin Infect Dis. 2015;60(Suppl 2):S129-S134. doi:10.1093/cid/civ085
- U.S. Food and Drug Administration. Risk of Invasive Disease in Preterm Infants Given Probiotics Formulated to Contain Live Bacteria or Yeast. Updated August 9, 2024. fda.gov
- Guo Q, Goldenberg JZ, Humphrey C, El Dib R, Johnston BC. Probiotics for the prevention of pediatric antibiotic-associated diarrhea. Cochrane Database Syst Rev. 2019;4:CD004827. doi:10.1002/14651858.CD004827.pub5
- National Center for Complementary and Integrative Health. Probiotics: What You Need To Know. nccih.nih.gov
- McFarland LV, Evans CT, Goldstein EJC. Strain-specificity and disease-specificity of probiotic efficacy: a systematic review and meta-analysis. Front Med (Lausanne). 2018;5:124. doi:10.3389/fmed.2018.00124
- Hempel S, Newberry SJ, Maher AR, Wang Z, Miles JNV, Shanman R, Johnsen B, Shekelle PG. Probiotics for the prevention and treatment of antibiotic-associated diarrhea: a systematic review and meta-analysis. JAMA. 2012;307(18):1959-1969. jamanetwork.com
About the Vita Globe Editorial Team
The Vita Globe Editorial Team researches and writes our wellness content, working from peer-reviewed research, systematic reviews and guidance from bodies such as the NIH and the FDA. We cite our sources inline and update articles when the evidence changes.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for medical advice. Talk to your healthcare provider before starting any new supplement, particularly if you are pregnant, nursing, taking medication, or caring for a child.
