Although bismuth is considered non-toxic, prolonged use could have unfavorable side effects. Bismuth salts are insoluble. Hence, when consumed for gastrointestinal disorders, they can become toxic.  They are not easily absorbed because they are insoluble. As a result, 90% of ingested bismuth is eliminated in the urine, with the kidneys holding the largest percentage. Acute renal damage can result from bismuth compounds when taken in high concentrations. Despite this, there is no proof that bismuth causes cancer.