Hello and Welcome to HCM,
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Overexposure to the sun can result in serious sunburns that may actually cause blistering, as well as slight swelling of the affected area. The skin has to regenerate new cells in order to heal the burns, but certain treatments may be used to soothe the pain, including applying some aloe vera
gel - best if you get it from the plant and sometimes sold in supermarkets.
keep a cool bag of frozen anything on the inflammed part.
Hope this helps you.
Wishing you good health...