For high cholesterol, 300-1,2000 milligrams of niacin has been taken by mouth daily for 6-44 weeks as wax-matrix, immediate-release (crystalline); 2 grams of niacin has been injected into the vein over 11 hours. The maximum recommended daily dose is 3 grams.For high cholesterol (in combination with statins or bile acid sequestrants) 500-4,000 milligrams of extended-release or regular niacin has been taken by mouth daily for eight weeks to 6.2 years.or high cholesterol levels in HIV-infected patients 500-2,000 milligrams of extended-release niacin (Niaspan®) has been taken by mouth daily for 44 weeks to two years. For high blood phosphorous levels, a single 375 milligram dose of extended-release nicotinic acid has been taken by mouth.