Cutar rashin lafiya wani yanayi ne na likitanci wanda garkuwar jiki ke kai hari ga sel masu lafiyayyen sel da kyallen jikin ta, suna kuskuren cewa mahara ne daga kasashen waje. Wannan na iya haifar da kumburi, zafi, da kuma lalata gabobin jiki da kyallen takarda daban-daban a cikin jiki, dangane da wane bangare na jiki ya shafa. Misalan cututtuka na autoimmune sun haɗa da rheumatoid arthritis, lupus, multiple sclerosis, da kuma Type 1 diabetes.