The aims of this systematic review and meta-analysis were to produce a comprehensive survey of the serum levels of interleukins (ILs) in untreated people with endometriosis compared with people without endometriosis.

A systematic literature search of English language studies within Cinahl, Medline Complete, PubMed, and Scopus from inception to May 2023 was performed.

We included studies that compared IL serum levels in people with endometriosis to those without endometriosis. Meta-analysis was performed on IL-1RA, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-17A, IL-18, IL-23, and IL-37.

The systematic search retrieved 651 studies, of which 77 underwent a full-text review. A total of 30 studies met inclusion criteria for the meta-analysis. IL-1Ra, IL-6, and IL-37 serum levels were 2.56 (95% CI 2.20–2.92, p <.001), 1.38 (95% CI 0.58–2.17, p <.001), and 1.77 (95% CI 1.33–2.20, p <.001) standard deviations higher in the patients with endometriosis compared with patients without endometriosis while IL-23 serum levels 0.40 (95% CI –0.73 to –0.07, p = .02) standard deviations lower, respectively.

There is mounting evidence that ILs, especially IL-6, may be good candidates for unique noninvasive diagnostic tools and/or treatment pathways for endometriosis.