Mangel is absolutely right, I am a cop, and have seen dead children as a result of huffing air and actually any aerosol. Tell a responsible adult right away. You just may save a life.
Your friend has a very dangerous addiction that cause permanent brain damage and ultimately death. When the heart is not working good, the legs will swell. This is a VERY bad sign that he is nearing the end stage of his addiction journey. Tell his family..Call 911 if he passes out..do ANYTHING to get him to wake up. Good luck to you and your friend.
yes you asked the right person i am actually very allergic to doing that so i couldnt give you much info exept the swelling is normal and i would recommending going to the doctor just to make sure