Final answer:
Alcohol is the most commonly used antiseptic for routine venipuncture due to its ability to rapidly kill microbes and its ease of use.
Step-by-step explanation:
The most commonly used antiseptic for routine venipuncture is alcohol. Isopropyl alcohol, particularly in a 70% aqueous solution, is effective at denaturing proteins and disrupting membranes of microbes, quickly killing them. It is also a part of hand sanitizers in a concentration range of 60% to 80%. Alcohol-based antiseptics are favored for their broad-spectrum effectiveness against vegetative microbes and their ease of use. Though iodophors like povidone-iodine are common in surgical settings for skin antisepsis before incisions, alcohol is the preferred choice for routine venipuncture because it is fast-acting and less irritating to the skin than iodine solutions.