Joint inflammation, or spondyloarthritis (SpA), is the most common extra-intestinal manifestation of inflammatory bowel disease (IBD), but the specific role for therapies targeting SpA is not well defined. One of the earliest medications used for the treatment of IBD is sulfasalazine (SAS). SAS is a prodrug composed of two chemical moieties, the anti-inflammatory 5-aminosalicilate and the antibiotic sulfapyridine. The efficacy of SAS in peripheral arthritis is thought to depend on its “antibacterial” properties, however the impact of SAS on the IBD-SpA microbiome and how it may improve extra-intestinal symptoms is unknown.