Hectorol (doxercalciferol) and Renagel (sevelamer hydrochloride) are both medications used to manage conditions related to chronic kidney disease (CKD), but they work in different ways. Hectorol is a vitamin D analog that helps lower parathyroid hormone (PTH) levels in people with CKD, including those on dialysis. It is available as capsules and an intravenous (IV) injection. Renagel, on the other hand, is a phosphate binder used to treat high phosphate levels in the blood (hyperphosphatemia) in adults with CKD who are on dialysis. It comes as tablets taken by mouth with meals. While Hectorol can raise calcium levels, Renagel does not contain calcium, making it a good choice for those with high calcium levels. Hectorol is typically taken once a day or three times a week, depending on the form, while Renagel is taken three times a day with meals. Common side effects of Hectorol include infection and constipation, whereas Renagel may cause nausea, vomiting, and diarrhea. Hectorol interacts with many medications, including calcium and vitamin D products, while Renagel can affect the absorption of certain vitamins and minerals, such as vitamins D, E, and K.