Final answer:
Ethyl alcohol (ethanol) and isopropyl alcohol (isopropanol, rubbing alcohol) are commonly used to cleanse puncture sites before needle injections, typically in a 70% aqueous solution for effective disinfection.
Step-by-step explanation:
The type of alcohol used to cleanse the puncture site before needle injection is typically either ethyl alcohol (ethanol) or isopropyl alcohol (isopropanol, rubbing alcohol). These alcohols are effective in denaturing proteins and disrupting cell membranes, acting as disinfectants and antiseptics.
They are commonly used in concentrations of about 70% aqueous solution for skin disinfection because this concentration allows for effective penetration into cells without rapid coagulation of surface proteins that higher concentrations would cause. It's important to note that rubbing alcohol should be used only as a topical antiseptic and not for internal wounds or consumption, and it should be applied in a well-ventilated area due to its high volatility and inhalation hazards.