Sulfites in winemaking: Why? What’s the impact to me?

By Dave Schavone

Is there a more divisive question than why add sulfites to wine (aka sulfur dioxide, aka SO2)? Are they bad for you? Will they cause headaches? Are they natural? Let’s unpack some common misconceptions about SO2. Spoiler: you may not be able to get away with forgetting to drink water and blaming sulfites for your hangover.

Are sulfites really unnatural?

First things first: sulfites occur naturally in winemaking, meaning even if the winemaker chooses not to add any SO2 at all, the wine may still contain sulfur. Many wines only have a few milligrams per liter, but it is not uncommon for a wine to have around 40 mg/L naturally occurring sulfites, and in rare cases it can be over 100 mg/L. [A quick note on measuring sulfites in wine: you’ll see the sulfite content represented in two ways—mg/L (milligrams per liter) and ppm (parts per million). Since there are 1,000,000 milligrams in a liter, the number is the same regardless.]

Ok, so then why do winemakers add sulfites to wine?

On top of those naturally occurring sulfites, most winemakers add additional SO2 at various points in the winemaking process. This serves two roles—protecting against bacteria and premature oxidation, both of which can spoil a wine.

In recent years, many people have repeated the notion that sulfites cause headaches. While it might be convenient to blame your hangover on sulfur, alcohol is the much more likely culprit. There are some people who have a sulfur allergy, but it is almost always linked to severe asthma and the reaction is respiratory in nature, not a headache. For people who have this allergy, they are aware of it well before they are of drinking age, as there are significant amounts of SO2 in many other things we eat or drink. The maximum SO2 legally allowed in wine is 350ppm. Compare that to over 3600ppm in dried fruit, or 1800ppm in French fries. The average canned soda has about the same amount of SO2 as the most commercially made, additive-laden wine.

Wait: so why do I have a headache?

So if it isn’t sulfur causing all those headaches, what is? The easiest answer is good ol’ dehydration. Alcohol is a diuretic, which means it sucks the fluids out of your system. In a nutshell: drink more water when you consume alcohol. It’s probably the best way to avoid those headaches. You can also try drinking less alcohol: as much as we’d like to blame a pesky ingredient for our hangovers, it might be solely on us (gasp).

Beyond that, a recent study shows a link between what are called biogenic amines and headaches. These are compounds that occur naturally in winemaking, the most commonly recognized of which is histamine. Many more people have a sensitivity to these than they do sulfur, and the symptoms of such a sensitivity more closely match the symptoms that sulfites get blamed for: headaches, nausea, and flushing. The irony is that the best way to limit these biogenic amines in wine is by adding sulfur before fermentation.

All things considered, SO2 is unfairly maligned in the wine world. The decision by many winemakers to not use sulfur is much more of an aesthetic choice than one based on any kind of health issues. For most people, using SO2 in the right quantities will result in wines that are more enjoyable and less volatile. RedThumb chooses to add sulfites to our wines right at bottling, and only enough to ensure a consistent, delicious flavor every time you pop a new bottle.