When minor wounds are required to be cleaned or stitched up, local anesthetics are typically used to reduce pain . But, according to the National Institutes of Health , these local anesthetics were often considered the most painful part of the procedure. They found that cooling with ice cubes could significantly reduce pain .

There are multiple ways to reduce the pain associated with local anesthetic administration. The study authors identified some possibilities, which included mixing the local anesthetic with sodium bicarbonate, applying to a mixture of local anaesthetics (EMLA) cream, and warming lidocaine close to body temperature.

Here the authors point out, when lidocaine is buffered with sodium bicarbonate or warmed close to body temperature, its shelf life is shortened. Besides, additional equipment is required for its storage; tiny precipitates form after mixing with sodium bicarbonate, and EMLA cream has not been approved for use on open wounds.

The words noted that the Greek philosopher and Hippocrates described the technique of applying cold to reduce pain. Several studies have also shown that when veins and arteries need to be punctured, to cooling spray or ice cubes effectively reduced pain.

Dr. Sang Chun Choi and colleagues included 50 patients (ages = 18 to 65), who had simple lacerations repaired in the emergency department to assess the relief in pain attained with ice cubes. Cryotherapy (an ice cube is placed inside a sterile glove applied to the wound for two minutes before a lidocaine injection) was received by half of the patients. The other patients received standard care, with no special treatment before the injection.

On a scale of 1 to 10, patients were asked to rank their pain after the injection. Half the patients ranked their pain level as higher than 2 in the ice cube group, whereas in the control group half the patients had a pain score of 5 or higher.

Cryotherapy significantly reduced patient perceived pain from local anaesthetic injections, without increasing thread complications.

Study authors said, "Cryotherapy appears to be safe, pragmatic and effective," and said that it does not require the modification of anesthetic administration, any special equipment, or additional expenses, to reduce pain associated with local anesthetic injections.