Cluster headaches. Its rather amusing to watch the video below (an older white male from Texas who takes shrooms to treat his cluster headaches) especially when the guy (in the full video) talks about how he hates his treatments, that it is onerous for him to have to trip.*
I also recall seeing something about 10 years ago that scientists were looking into using MDMA (Ecstasy) for the treatment of patients in hospice, as they found that it had the amazing ability to eliminate their anxiety over dying.
I'd never say MDMA is something people should try, but psilocybin (or other forms of "magic" mushrooms are another thing entirely. Personally, I think everyone should try them at least once. There has even been some evidence in the past decade or so that many early Christian groups used magic mushrooms in their religious practices.
- NOTE: I wasn't amused by the pain this guy went through, I've experienced it myself. I was amused at how he talked about doing mushrooms and hating it.
-Brandon Sanderson, The Way of Kings