For many wine drinkers, one of the first things they consider when buying wine is whether their bottle contains headache-inducing sulfites. But are sulfites as bad as they are painted out to be? Do they really cause headaches, and if so, how does one avoid them?

The term “sulfite” refers broadly to a group of chemical compounds that contain sulfur in them, the most common being sulfur dioxide, SO₂. Sulfites are found everywhere, in nature and in manufacturing; among many, many other things, they develop naturally in the human body, are used in drying fruit, and most importantly for our purpose, are used as a preservative in wine. Sulfites are added to nearly every commercially available wine to protect against oxidation, and to prevent bacteria from forming in the bottle. Sulfites occur naturally in wine during fermentation, but in most wines, additional sulfites are added to safeguard against spoilage. While wines labelled as “sulfite-free” do exist, it’s worth noting that the label is not technically true; a wine can be labelled sulfite-free if it contains less than 10 mg of sulfite per liter, and it would be incredibly difficult to fully remove sulfites from wine, if it’s possible at all.

So sulfites are everywhere in what we consume — does this mean you should just stay home and hide to avoid those uncomfortable allergic reactions? Probably not. While an unlucky few with sulfite allergies certainly exist, the FDA notes that sulfite sensitivity is much rarer than many realize. If wine is giving you headaches, it’s likely not from the sulfites, but instead from the histamines which also naturally occur in wine, which have been shown cause headaches by way of dilation of the carotid artery, which leads to a drop in blood pressure. There are no histamine-free wines, but if you regularly get headaches after having a glass, talk to your doctor, and maybe she could suggest an antihistamine to take before drinking. And of course, wine has alcohol in it, which has a dehydrating effect. Dehydration is a big part of what causes a hangover, which are typified by — of course — bad headaches.

Still not convinced? Though as we’ve noted there’s no such thing as a sulfite-free wine, by buying organically-grown wines you can at least have a bottle with no sulfites added. Be aware that when picking up such a wine, you’ll have to drink it sooner than you would a sulfite-laden Cabernet. Without the preservative effect the sulfites give, a wine will spoil and become undrinkable quickly. And it’s worth noting that, at least in our experience, organic bottles don’t tend to be especially impressive wines.