Walk through any wine section and you'll see "contains sulfites" on almost every bottle. For many wine drinkers, this raises questions. What are sulfites? Are they harmful? And do they cause headaches?
What Are Sulfites?
Sulfites — more precisely, sulfur dioxide (SO₂) — are a natural byproduct of fermentation. Wine contains them even if nothing has been added. They're also added deliberately by winemakers as a preservative and antioxidant, because sulfur dioxide is remarkably effective at preventing spoilage and keeping wine stable during aging and transport.
The use of sulfur in winemaking goes back centuries. Before the chemistry was understood, winemakers burned sulfur candles in barrels after cleaning them, instinctively recognizing that it helped keep the wine fresher longer.
How Much Is in Your Wine?
The level of sulfites in wine varies considerably. Sweet wines generally have more, because the residual sugar creates an environment where bacteria and yeast can easily resume fermenting — sulfites help prevent this. Dry red wines typically have the lowest sulfite levels among wines, though they're not sulfite-free. Dried fruits such as apricots contain far higher concentrations of sulfites than wine does.
Do Sulfites Cause Headaches?
This is one of the most persistent myths in wine culture. The short answer is: for most people, probably not. The headache most commonly associated with wine is more likely caused by alcohol itself, histamines (which occur naturally in red wine), or dehydration from drinking without adequate water.
For most wine drinkers, sulfites at the levels found in wine are well tolerated. Those with severe asthma or known sulfite sensitivities may wish to take note, and a health professional is the appropriate source of medical guidance on that topic.
What About "No Added Sulfites" Wines?
Some winemakers choose to add no additional sulfur dioxide, relying instead on careful winemaking technique to keep the wine stable. These wines are sometimes labeled "no added sulfites" or "made without added sulfites." They can be excellent, but they're typically more delicate and may have a shorter shelf life than conventionally made wines. They also generally require more careful handling and storage.
Organic wine certification has varying rules about sulfite additions depending on the certifying body and the country of origin. In the United States, wines labeled "organic" may contain no added sulfites; wines labeled "made with organic grapes" may have some added.