Make sure you're using the right FormID. Where in your load order is Hypothermia loading? That number (in hexadecimal) is the first two digits of the FormID. So, the command would look something like
player.additem xy0025a9 1
Where xy is the mod's position in the load order.
Edit: Another thing you can do is use the help command. Just open up the console, type in "Help [name]" ( [name] is the name of the item in question). That should give you the FormID (among other information).