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How to treat a blister burn 
Run cool water over the blister. 
The first thing you can do to treat a blister burn is to run cool or lukewarm water over the affected area. You can also use a cool bath or press a towel soaked in cool water on the burn.
Keep the affected area in the cool water for 10 to 15 minutes. Make sure you are using cool water and not cold or ice water.