Probiotics and Bloodstream Infection: Immunocompromised People, Central Lines, ICU Patients and Case Reports

Urgent first

If you or someone you care for has a weakened immune system, a central line or is in intensive care, do not start a probiotic without the care team's approval. Fever, chills or feeling suddenly very unwell after starting one needs prompt medical care; in the US call 911 for an emergency. The NHS (UK) advises talking to a doctor before any probiotic supplement if you have an existing health condition or a weakened immune system. [1]

What this page covers

Probiotics are live bacteria or yeast. In people with a healthy gut lining and immune system they usually stay in the gut. In very sick people the concern is that live microbes could pass from the intestine into the blood, or enter through a catheter; the AGA technical review describes this as the reason probiotics are used with caution in immunocompromised and critically ill people. [2] This page reports what the sources say about that risk. It does not tell anyone to start, stop or change a treatment.

What the sources found

Yeast probiotics: what the case series show

Saccharomyces boulardii is a yeast sold as a probiotic. The 2023 systematic review found the risk factors most linked to probiotic-associated fungemia were intensive care stay (31.5%) and parenteral or enteral tube feeding (29.6%) among the cases. [7] Overall mortality in the whole cohort was 36.1%, and the review did not report a significant difference between patients who had and had not received the probiotic. [7] These are cases that were reported, so they cannot show how often fungemia happens among all users.

A Belgian retrospective study of 10 patients with S. cerevisiae fungemia found an S. boulardii-containing probiotic had been prescribed in 6 of them; the authors called the infection rare but life-threatening and suggested older age should be a contraindication to these products. [8] That is the authors' opinion from a small study, not an official rule.

Case reports

• A 46-year-old in intensive care after surgery for severe pancreatitis, with a central venous catheter, developed fever and low blood pressure after starting S. boulardii; blood cultures from central and peripheral lines grew S. cerevisiae. The authors proposed gut translocation and catheter contamination during probiotic handling as mechanisms. [9]
• A patient with C. difficile colitis and a central venous catheter developed catheter-related S. cerevisiae bloodstream infection after probiotic use; the author suggested removing the catheter may matter for outcome. [10]
• In children with short bowel syndrome, a systematic review of mostly case reports listed adverse effects including Lactobacillus sepsis (n = 3) and d-lactic acidosis (n = 2). [11]

Single case reports show that something can happen. They do not show how often, or whether a particular strain caused it.

Where reassurance does and does not apply

The 2025 Cochrane review concluded short-term probiotic use is likely not associated with adverse effects in people receiving systemic antibiotics who are not immunocompromised. [12] That finding does not cover immunocompromised people. A 2026 meta-analysis of long-term trials in at-risk groups could not draw conclusions about long-term safety because adverse-event reporting was inconsistent. [13] A 2026 review states rare infectious complications have been reported in high-risk patients. [14]