Sulfites have become one of the most blamed, least understood compounds in a wine glass. In the U.S., the declaration appears on nearly every wine label because it is required for wines containing 10 ppm or more of sulfites, and they get fingered for headaches, flushing, and next-day misery with remarkable confidence, confidence that, when you look at the actual evidence, turns out to be largely misplaced. Here is what sulfites really are, what they do, and what's more likely responsible for how you feel after a few glasses.
What Sulfites in Wine Actually Are
Sulfur dioxide (SO₂) is a simple compound of sulfur and oxygen. In winemaking, it does two jobs: it inhibits the wild bacteria and yeasts that would otherwise spoil the wine, and it acts as an antioxidant, slowing the chemical reactions that turn wine flat and brown. Winemakers have used sulfur in some form for centuries, burning sulfur wicks inside barrels is a practice with roots going back to ancient Rome.
Here is the detail that often surprises people: fermentation itself produces sulfites. Yeast generates small amounts of SO₂ as a metabolic byproduct, which means a wine labeled 'no added sulfites' still contains sulfites, just at lower levels. There is effectively no such thing as a completely sulfite-free wine. The legal threshold for the 'contains sulfites' declaration in the U.S. is 10 parts per million; most conventionally made wines fall somewhere between 80 and 200 ppm. For context, dried apricots typically contain over 2,000 ppm.
Why the Label Says 'Contains Sulfites'
In the United States, the 'contains sulfites' label has been required since 1988, driven by concerns about a small population with genuine sulfite sensitivity, primarily people with severe asthma. For that group, sulfites can trigger respiratory symptoms, and the warning exists for them. Genuine sulfite allergy or intolerance is relatively rare, estimated to affect around 1% of the general population and up to 5% of people with asthma.
The label was never intended to suggest that sulfites cause headaches or hangovers in the general population, but that is exactly how it got read by millions of consumers. Seeing a warning on every bottle, people understandably connected it to whatever felt bad after drinking. The connection was intuitive and wrong.
If you do not experience breathing difficulties after foods known to contain sulfites, sulfite intolerance is less likely to be the explanation, but sulfite content varies widely by product, so discuss suspected reactions with a clinician.
Do Sulfites Cause Wine Headaches? What the Evidence Says
The short answer is: almost certainly not for most people. Studies specifically designed to test whether sulfites cause headaches in healthy adults have not produced compelling evidence that they do. A true double-blind challenge, where participants drink wine with varying sulfite levels without knowing which is which, has not confirmed sulfites as the culprit.
Several other compounds are more plausible candidates. Histamines, which are higher in red wine than white, can cause flushing and headache in people who lack sufficient diamine oxidase, the enzyme that breaks histamines down. Tannins have also been implicated, possibly through their effect on serotonin levels. Then there is the simplest explanation: alcohol itself, dehydration, and the congeners (fermentation byproducts like acetaldehyde) that the liver processes after a few glasses.
The cruel irony of the sulfite myth is that white wine typically contains more added sulfites than red, winemakers add more to protect delicate aromatics and color. If sulfites were the main driver of wine headaches, white wine drinkers should suffer more. Most people report the opposite.
Natural, Organic, and Low-Sulfite Wines: What Those Labels Mean
Wine labeled 'made with organic grapes' in the U.S. may still contain added sulfites. Wine labeled 'organic wine' under USDA rules may not contain added sulfites, though it will still have naturally occurring ones. In Europe, the rules differ: 'organic wine' there permits small amounts of added SO₂, just at lower limits than conventional wine. Reading the label carefully matters because the category names do not map neatly across borders.
'Natural wine' has no legal definition in most markets, but the movement broadly favors little or no added sulfur. The tradeoff is real: lower sulfite wines are more fragile, more prone to spoilage during shipping and storage, and more variable from bottle to bottle. That is not a knock. It is just the physics of what SO₂ does. If you are buying low-sulfite wines, keep them cool, drink them young, and do not leave them sitting in a warm car.
For most healthy drinkers, going low-sulfite will not cure your wine headaches. If it does seem to help, the cause may be another aspect of the wine or drinking context; minimal-intervention wines are not reliably lower in histamines.
So What Should You Actually Do?
Drink water. Seriously, alternating water with wine addresses dehydration, which amplifies every other effect alcohol has. Eating before and during drinking slows alcohol absorption meaningfully. These two habits will do more for how you feel the next morning than switching to any particular wine style.
If you consistently react to wine but not to other alcoholic drinks, a histamine response is worth investigating, a doctor can help assess that. Keep a simple tasting journal noting what you drank and how you felt; patterns become obvious quickly over a few weeks, and the details you track (grape variety, region, producer, approximate sulfite level if listed) can help you identify what actually triggers a reaction for you.
If you have asthma and react to sulfites in food, talk to your doctor before assuming wine is safe because it has a lower sulfite level than dried fruit. For everyone else, the 'contains sulfites' label is best understood as routine consumer information, not a health warning aimed at you.