NEW research suggests that long-term use of salicylic acid-based analgesics may lead to significant changes in gut microbiota and circulating metabolites, with potential implications for patient management in primary care.
Although analgesics are widely used, especially non-steroidal anti-inflammatory drugs (NSAIDs) and salicylates, their long-term effects on gut health remain poorly understood. Existing observational studies have hinted at a link between analgesic use and gut microbiota disruption but cannot establish causality. To address this, researchers conducted a two-sample Mendelian randomisation study using summary-level genetic data from large-scale genome-wide association studies, including 466,457 UK Biobank participants and 18,340 individuals from the MiBioGen consortium. The study focused on four common classes of analgesics: NSAIDs, salicylic acid, opioids, and anilides.
The analysis revealed a suggestive causal relationship between NSAID use and increased abundance of Eubacterium xylanophilum, a member of the gut microbiome. Significantly, salicylic acid use was associated with notable shifts in gut microbiota composition. It correlated positively with the family Prevotellaceae (P=0.006) and negatively with eight microbial traits, including genera Clostridiumsensustricto1, Adlercreutzia, and Akkermansia, as well as several members of the Verrucomicrobia phylum (P=0.009–0.043). Additionally, salicylic acid use was causally linked to four circulating metabolites: acetoacetate, creatinine, omega-3 fatty acids, and triglycerides in very large high-density lipoprotein (P=0.005–0.046). No consistent evidence emerged for gut microbiota changes linked to opioid or anilide use.
These findings provide early causal evidence that salicylic acid may substantially influence gut microbial balance and metabolic pathways. General practitioners should remain aware of emerging data when advising on long-term analgesic use, particularly in patients with existing gut-related or metabolic conditions.
Reference
Wei F et al. Assessing the impact of common pain medications on gut microbiota composition and metabolites: insights from a Mendelian randomization study. J Med Microbiol. 2025;74(6):002028.
