When considering preparations for a colonoscopy, most medications are not harmful to the body. In 2016, most preparations contain medications with low toxicity risks. Sodium phosphate was once used widely for colonoscopy prep, but was later found to have considerable risks such as digestive and kidney issues, severe dehydration, and ionic imbalances. It has since been replaced with medications that are better tolerated by the body. Some preparations may still be unsafe for certain groups such as those with kidney or heart issues, or those taking high doses of diuretics. For a young and otherwise healthy individual, the risk of toxicity is relatively equal among available preparations.