Although they are best known for spicing up marijuana, the body also produces cannabinoids, which are thought to play a part in learning and in communications between the immune system and the nervous system. Now, researchers have shown that cannabinoids can relieve some of the swollen, itchy agony of allergic skin reactions in mice.

The results suggested that cannabinoids produced by the body might help protect the animals against skin allergies.

But no therapeutic application is certain until the experiments have been repeated in humans, cautions Roman Rukwied, who studies pain and inflammation at the University of Heidelberg in Germany. "We are far before the day when we could say 'oh, I have a nickel allergy. I will smoke marijuana and I won't have it anymore'," he says. "That is definitely not the case."