Since early puberty I have been afflicted by severe acne. It has improved with time (I'm pushing forty), but at one time massive boils covered my chest, back, ass, and everywhere else, it seemed.
In my early twenties, I saw a dermatologist who said it was one of the worst cases he had ever seen. He prescribed tetracycline, which seemed to work for awhile, but then became ineffective and turned my skin orange, which was alarming. He finally resorted to direct injections of (some other) medicine into the boils, which was a nightmare, obviously.
I have smoked marijuana since I was a teenager, but rarely had a steady supply until I was much older. Once I was financially able to maintain a steady supply, I discovered something amazing: when I was smoking, my acne cleared up. When I ran out, my acne flared up. I have observed the change many, many times, and the evidence is clear to me. But I need to smoke on a regular basis for several weeks before the effects can be seen, which is why I never really noticed it when I was younger.
This is a medicine, pure and simple. My mind boggles at the venom our culture directs at such a useful, safe and friendly little plant.