cerebral edema
"I had a seizure which led to them finding a brain tumor. They put me on dexa in the ER and was on it for 2 months after the craniotomy to prevent brain swelling. Don't quite remember the dosing, it was a 1mg or 2mg pill I took 2 or 3 times a day. 

I had insomnia (slept maybe 3 hours a night even on two percocet every 4 hours), painful acne all over my face and back, mood swings, crazy hunger and weight gain, erectile dysfunction, headaches and joint pain. I suppose it did what it was supposed to, but the side effects were horrible. Even if I had another tumor, I don't think I'd ever use it again."