According to animal studies by researchers of the University of Bonn (Germany) the topical administration of THC in an ointment is able to reduce allergic skin reactions. Their research was published in the journal Science on 8 June. Endocannabinoids were shown to play an important role in regulating inflammation processes. Increased endocannabinoid levels reduced inflammatory reactions in the skin of mice, which were made allergic against a certain allergen, while the absence of cannabinoid receptors increased these reactions.

When inflammation occurs the endocannabinoids act like someone stepping on the brakes. They prevent the body from doing too much of a good thing and the immune reaction from getting out of control. This is consistent with the fact that at the beginning of the infection the endocannabinoid concentration increased in the mice. If the skin was treated with a THC solution shortly before and after applying the allergen, a lot less swelling occurred than normal. Ointment like this would probably not have an intoxicating effect.

More at:
in English: http://www.sciencedaily.com/releases/2007/06/070607171120.htm
in German: http://www1.uni- bonn.de/pressDB/jsp/pressemitteilungsliste.jsp

(Source: Press release of the University of Bonn of 7 June 2007, Science Daily of 7 June 2007)