A friend of mine recently mentioned that she can't drink red wine because it has sulfites in it., and they give her headaches. I was a bit startled because pretty much all wine has sulfites, either naturally, as a byproduct of the fermentation process, or as a preservative.
In 1987 the U. S. Food and Drug Administration (FDA) began requiring that any food that has more than 10 parts per million of sulfites needs a warning label that says "contains sulfites." Sulfites are frequently used as a food preservatives because they removes the oxygen that bacteria need to survive. Sulfites are commonly used in the production of wines, sausages, fruit juice and bagged salad products. Dried fruit in particular is preserved with sulfites, so anyone who has a problem with sulfites in wine will likely have a problem with dried fruit.
Winemakers add sulfites to prevent micro-organisms, oxidation, and, particularly in red wines, discoloration. The ancient Egyptians and Romans would burn elemental sulfur in wine amphoras, producing sulfite residues which dissolved when the wine was added. The sulfites added to wine dissolve into either bound sulfites, when the sulfites join with other compounds during fermentation and thus don't affect the flavor or odor of the wine, or free sulfites which remove oxygen and thus prevent damage to the wine. Aged red wines have very little residual sulfite, and dry whites two to three years after bottling also tend to have fewer sulfites.
People who are allergic to sulfites should avoid them, of course, especially people who are asthmatics, since they seem more susceptible than the general population. It is possible to avoid sulfites by sticking to wines that are certified as organic or biodynamic; those wines sulfite content are regulated and are generally required to be no more than 100 parts per million. Washington wineries produce a variety of organic wines.
Since aged red wines typically have lower amounts of sulfites than white wines. I suspect that my friend was reacting not so much to the sulfites, but suffered the so-called "Red Wine Headache," a phenomena that isn't completely understood, but which does affect many people. There's a good discussion of the issues here.
There's a third problem with sulfur and wine, sometimes, in that occasionally when you open a bottle of wine you'll catch a faint whiff of sulfur; it might remind you of rotten eggs, or of the scent of a just-struck match. Sometimes, all you have to do is decant the wine, and let it breathe a bit. But if the odor lingers, you might want to try "the penny trick," if you have an older, clean, genuinely copper penny, drop it into the wine. Alternatively, a gentle stir or two with a sterling silver spoon will work just fine. Either method causes the sulfur odor to dissipate, and you can enjoy your wine.