In football, you often see a player gets injured. Then the physio comes and they use a spray often called as "magic spray". Does anyone have any idea what it is?
Looking for the actual details.
The spray is actually a burst of very cold water/mist with ingredients to help/make it cool (I don't have one on hand to know what is inside). The term 'magic' can refer to its history and the seemingly miraculous way the player gets back on his feet.
It is cold because it can help with reducing inflammation which in turn can reduce pain on knocks / joints.
You may also get a heat spray which can help muscles.
It contains anesthetics. When players get hit or tackled they could be in great amount of pain, but their team still needs them to play. The physicians apply the spray and the injured body part goes numb, so players can continue playing with no pain.
The spray is an aerosol containing menthol. Menthol cools, and the act of spraying aerosol is cooling. (Boyle/Charles/Combined Gas Laws -- when the pressure of a gas is reduced, the temperature goes down.) By drastically cooling the area, it applies temporary pain relief. Very temporary, but for minor dings it gets rid of the pain so they can play. Most (male) soccer "injuries" are really only acting for a foul anyways.
One product that is used in various sports is BioFreeze(TM), which I have seen used in my work in ER (as a Sports Medicine PA). They describe on their website that Menthol is "the active ingredient in Biofreeze Pain Reliever", and explain how cooling and menthol can relieve pain.