What size needles are used for routine butterfly venipucture?

For routine butterfly venipuncture, 21-gauge or 23-gauge needles are commonly used. The 21-gauge needle is typically preferred for adults due to its larger diameter, allowing for faster blood flow, while the 23-gauge needle is often used for pediatric patients or those with smaller veins. The choice of needle size may also depend on the specific requirements of the procedure and the patient's condition.