Alcohol used for disinfection is a 75% ethanol solution because 75% ethanol solution can achieve the best disinfection effect. If the concentration of alcohol is too high, the bacteria will quickly dehydrate and form a protective film on the surface. The alcohol will not be able to enter the bacteria, which is not conducive to sterilization. If the concentration of alcohol is too low, it will not play a role in sterilization, and the bacteria are still active.

When disinfecting in the hospital, if the patient’s wound is open or before the wound has healed after surgery, it is disinfected with iodophors, such as knife and gunshot wounds. For closed wounds, such as internal wounds caused by fractures, or internal wounds caused by broken feet, alcohol is used for disinfection.

Iodophor is less irritating to the wound than alcohol, so disinfecting an open wound with iodophor is more beneficial to healing. Usually, the surgeon will disinfect the surgical area with iodophor before the surgery because it is more effective in killing bacteria than alcohol, and disinfection will be more thorough. If the disinfection is done without a wound, it can be disinfected with alcohol. For example, needle sticks inside a hospital are disinfected with alcohol.

However, disinfecting is not always possible in special cases according to the rules above. For example, if the patient is allergic to alcohol or iodophor, then other disinfection methods will be chosen.