Not many scientific studies can help you hook up. But here's one that comes with its own pick-up line: "Let's make out - it'll help your allergies!"
A study in the fantastically named Journal of Psychosomatic Research set out to determine whether kissing affects the production of allergen-specific IgE antibodies, the proteins made by your body that trigger the sneezing, sniffling, and general misery associated with allergies. Apparently, it does.
The test subjects were 24 patients with eczema and 24 patients with hay fever. Because the patients were "Japanese, and they do not kiss habitually," the (also Japanese) scientist conducting the study felt compelled to set the mood:
In the kissing study, subjects from one group kissed with their lover or spouse freely for 30 min alone in a room with closed door while listening to soft music (Beauty and the Beast, When You Wish Upon a Star, My Heart Will Go On, Love is a Many Splendored Thing, Moon River, Sunrise Sunset, Can You Feel the Love Tonight).
To make sure any differences weren't simply due to the (potentially ill) effects of listening to saccharine Disney music for 30 minutes, a control group was also tested:
In the control study, which was conducted after 2 weeks, each subject from two groups embraced a lover or spouse, but without kissing, for 30 min in the same room while listening to the same music.
The researcher collected blood from each patient before and after the snogging session to determine their IgE levels. In each case, the IgE levels of the members of the kissing group were significantly lower after their closed-door session. Because a decrease in IgE was not seen in the embrace-only group, the author concluded that kissing can alleviate allergies, likely due to its overall stress-reducing effects.
Lillian Fritz-Laylin and Meredith Carpenter run NCBI ROFL, a blog devoted to scientific malingering.