Have a friend who is deathly allergic. And not just to a particular strain, but to ALL marijuana. The sensitivity developed when she was about 23 years old. If she is even near the aroma of it she breaks out into hives and immediately begins to get a severe migraine. Her boyfriend couldn't even smoke in the house anymore. She's been to several doctors about it, but nothing has helped. It's very strange that she use to be able to smoke but now can't even get near it. At first keeping the smoke away was enough, but eventually it got to the point where even if he had touched it recently, unless he washed his hands she would start to have a severe allergic reaction. At first we thought she was just playing it up, but several "secret" experiments later it was clear that her body had become a warning signal for the presence of marijuana. They recently had a child, and between the two off them are so scared that the allergy could be genetic that he doesn't even smoke anymore.