Why some intravenous medications need to dilute before administering?

Answer 1

Primarily because they may cause phlebitis or tissue necrosis if given undiluted. This may be because of the acidity/alkalinity of the product, or the high osmolarity of the solution. One common example is an anti-nausea medication called Phenergan, which often causes pain if given undiluted and has even caused loss of fingers due to necrosis and tissue destruction.