A cannula needle for reducing injection force in connection with high viscosity fluid medications or medications with wide viscosity ranges. The cannula needle includes a skin penetrating segment, an enlarged rear end segment, and a transition segment disposed between the skin penetrating segment and the enlarged rear end segment. The skin penetrating segment includes a substantially uniform outer diameter and a substantially uniform inner diameter for patient comfort. The enlarged rear end segment has an inner diameter that is greater than the inner diameter of the skin penetrating segment. The transition segment includes a funnel shape for fluidly connects the inner diameter of the enlarged rear end segment and the inner diameter of the skin penetrating segment.
