Over the past decade, the microbiome has become a growing area of interest in health & medicine. One aspect of microbiome health that has become increasingly popular in recent years has been the use of probiotics. Probiotics are live bacteria that confer health benefits to users when administered in adequate doses. Evidence suggests that probiotics may manage and improve a variety of symptoms and diseases, such as Irritable Bowel Syndrome, Antibiotic-Associated Diarrhea, Inflammatory Bowel Disease, and many more. While probiotics possess advantageous attributes that make them a desirable intervention for digestive issues, gastrointestinal conditions, or overall gut health, it is important to note that probiotics are not infallible, or “one size fits all.” Despite being shown to be safe in most instances, there are certain safety considerations that must be made prior to probiotic use or administration. Furthermore, since probiotics are unique, specific, and differ at the strain level, their efficacy cannot be generalized across all species, product, or patient types.

One safety implication of probiotic use is the potential for negative interactions to occur if other drugs are being taken at the same time. For example, probiotics containing Lactobacillus and Bifidobacterium species have been found to interact negatively with antibiotics, and probiotics containing S. boulardii have been found to interact with oral systemic antifungal medications. Caution is also typically advised if probiotics are administered with immunosuppressants.

However, not all probiotics have negative drug interactions; there are some probiotics that can be used safely in conjunction with other medications, depending on their composition. Probiotics may also present mild side effects in users, such as gas and bloating.

These side effects are common and self-limiting, and typically occur due to changes in the gut microbiota that result from probiotic use. More significant side effects and/or probiotic sepsis may occur in individuals with underlying health conditions, as they are at an increased risk of illness and infection. However, research has shown that there are specific strains of bacteria that can be used safely, even among vulnerable populations (e.g., preterm infants, patients with HIV, cancer patients, etc.). This exhibits the importance of strain specificity and shows how correctly attributing clinical data to probiotics at the strain level is crucial when considering the safety & efficacy of probiotics. As such, it is important for pharmacists and healthcare providers to properly monitor probiotic use in patients (i.e., by documenting strain, format, dose, and potential adverse events/benefits) in order to ensure that probiotics are working effectively, and in a safe way.