Wine allergies and intolerances are topics that I don't pretend to know much about, but hear discussed in a restaurant on a regular basis. Some people can suffer from headaches, flushing, itching and nausea after just one glass. There's a lot of confusion and the buzzword is sulfites (also spelled sulphites). I'll sometimes hear "I can't drink red wine because I'm allergic to sulfites." This never made a lot of sense to me—winemakers tend to add more sulfur dioxide during the production of white wines than they do with red, especially whites that have residual sugar. The problem is that food sensitivities and intolerances are hard to pin down, wine is a complex mix of chemicals, and there isn't a lot of easy information available.
A true allergy is a hypersensitive immune response to the allergen. An allergy to a compound in wine (like sulfites) can be serious (hence the labeling requirements), but are also very rare. The most common reactions are food intolerances to sulfites or histamines. As byproducts of fermentation, both are natural compounds found in wine, but sulfites (an inclusive term for sulfur dioxide, sulfurous acid, and other forms) are also often added at stages throughout winemaking for all kinds of purposes, mostly because they are used as an anti-microbial and antioxidant.
In Jamie Goode's book The Science of Wine, he suggests an easy test for people who believe their reactions are linked to sulfites: see if you get the same reaction if you eat a packaged fruit salad from the grocery store, or dried fruit (particularly apricots). These products contain sulfites in much higher levels than you would find in wine.
Histamines in most cases, he says, are the true villains of wine intolerance. They can cause symptoms like headaches, flushing, itching, nausea, and more. Red wines contain anywhere between 0.6 and 4 grams per litre of histamines and whites have far less. This would explain the wine drinkers who suffer the effects from red wine, but not white. Goode suggests taking an antihistamine before you drink and seeing if it makes a difference.
Maybe some people know they have an issue with histamines and just say sulfites, because there's a better chance the restaurant staff will understand. I'm still waiting for the day I hear someone say, "I can't drink red wine because I have a histamine intolerance."
Jake Skakun is a writer and sommelier from Vancouver, currently living in Toronto. He can be found most days pulling corks and twisting caps at the Black Hoof. He Tweets and Instagrams @jakeskakun.