Choosing between a 21G and a 23G butterfly needle affects blood flow, patient comfort, and hemolysis risk. The wider 21G gives faster, steadier flow and suits routine adult draws on average-to-large veins. The narrower 23G is gentler and ideal for small, fragile, rolling, pediatric, or geriatric veins, though flow is slower.

Rule of thumb: assess the vein first, choose 23G for small or difficult veins, and prioritize a confident first stick over a faster draw. Whichever gauge you use, pick a sterile, single-use, safety-shielded set.

Shop 21G and 23G BD Vacutainer butterfly needles at Mudomed.