According to Dr. Herbert Kaufman, a member of the Medical Board of AWARE (American Wine Alliance for Research and Education) in San Francisco, in response to an inquiry presented to him by the Wine Enthusiast magazine (Volume 7, Number 3, April 1994):
“..The substance or substances which causes nasal congestion from wine have not been all identified, but some things have been demonstrated not to be the cause. Those include both histamine and a substance called seatonin. Regarding sulfites: While it is possible that sulfites can cause nasal flushing, itching, nasal congestion and even wheezing, there are other foods such as shrimp, prepared potatoes, sauerkraut, dried fruit, various prepared dips, beer and other beverages which contain greater concentration of sulfites than wine. So other foods should be causing the same symptoms.
“The exact mechanism of symptom production from sulfites is thought to be through release of breakdown products of sulfites themselves. One reason that sulfites are probably not the cause of [a person's] congestion is that the daily adult consumption of sulfites in the U.S. is approximately 160 mg. Wine contains only 100 to 400 parts per million (ppm); one ppm is equivalent to less than 1 mg. of sulfites in a full 750ml bottle of wine. In the actual fermentation and production of wine, sulfites are generated; therefore, even if no sulfites are added during the early stages of production, there will still be some sulfites present in all wines.”