Toxic epidermal necrolysis is a severe form of Stevens-Johnson Syndrome. It’s a life threatening skin reaction that’s thought to be caused by an immune response to certain medications. The medications known to trigger TEN range from ibuprofen, certain antibiotics (penicillin being one), anticonvulsants, and steroids. We aren’t sure what exactly causes it or how to stop it. One day you’re taking something for your headache, a few days later you start getting painful red splotches on your skin. Once the first ones show up, they spread, often across your entire body. The redness grows and gets more painful, blisters form, and then your skin starts falling off! Everywhere! The only level of care at this point is to treat you like a severe burn patient, because that’s essentially what you are. With large swathes of skin completely gone from your body, the only recourse is skin grafts and management of symptoms. Infections are common during the healing process and the prognosis isn’t great. If it progresses into TEN, the odds of survival are about 50%. But don’t worry, it’s so rare and triggered by so many different medications it’s pointless to try to avoid it. If the good Lord decides to kill you with it, there’s nothing you can do about it!
Ground white pepper should do the trick if you have some. It’s 99% heat and 1% pepper flavor so it would be a good stand in for horseradish. My brain first went to ground ginger but it won’t really be a good sub for horseradish. Though it may taste good given the other ingredients. If you don’t have white pepper, I’d just up the cayenne. It doesn’t have that nostril burning quality to it but it’ll be spicy nonetheless