Sulfites in Food: Wine, Dried Fruit, and the Asthma Question

You pour a glass of wine or open a bag of dried apricots and there it is on the label: contains sulfites. Maybe you have heard sulfites give you a headache, or that they are the reason some people cannot drink wine. Most of that reputation is wrong. A small part of it is very real, and worth knowing if you have asthma.

What Sulfites Actually Are

Sulfites are not one chemical. They are a family. The group includes sulfur dioxide gas (SO2) and a handful of salts that release it once they hit moisture: sodium sulfite, sodium bisulfite, potassium bisulfite, sodium metabisulfite, and potassium metabisulfite. Whatever the starting form, the active agent in food is sulfur dioxide and the sulfite ions it produces (FARRP, University of Nebraska).

They are partly natural. Yeast make small amounts of sulfur dioxide during any fermentation, which is why every wine, even one with nothing added, carries some sulfites. Winemakers and food processors then top that up to reach a useful dose.

The Two Jobs They Do

Sulfites earn their place by doing two unrelated jobs at once.

The first is stopping browning. Cut an apple and it goes brown within minutes. That color is an enzyme called polyphenol oxidase stitching oxygen onto the fruit’s phenols, the same basic process as iron rusting. Sulfur dioxide jams that enzyme like sand thrown into a gear, and it soaks up oxygen before it can react. This is why sulfured dried apricots stay bright orange while unsulfured ones turn the brown of a paper bag. Same fruit, same sugar, different color chemistry.

The second job is microbial control. Sulfur dioxide is toxic to wild yeast, mold, and many bacteria. In winemaking it is the workhorse that keeps unwanted microbes from souring the juice and turning a wine to vinegar. That antimicrobial role overlaps with preservatives like sodium benzoate and potassium sorbate , though sulfites are unusual in pulling double duty as an antioxidant too.

Why Wine Always Lists Them

Because there is no such thing as a truly sulfite-free wine. Fermentation makes some on its own, and most winemakers add more to keep the wine stable. US wine labels have to say contains sulfites once the level reaches 10 parts per million (FDA, 21 CFR 101.100), which nearly all wine clears. Winemakers have used sulfur dioxide for centuries, and burning sulfur candles inside barrels is an old trick for the same purpose.

Here is the part that trips people up. Sweet white wines and dessert wines usually carry more sulfites than dry reds, because pale color and residual sugar both need more protection. Dried fruit can carry far more than any wine. So if sulfites were the headache trigger, white wine and a handful of apricots should be worse than a glass of cabernet. For most people they are not.

The Headache Myth

The red wine headache is real. Sulfites are probably not the cause. Controlled tests have struggled to reproduce headaches from sulfites at the levels found in wine, and the stronger suspects are other compounds: histamine, tannins, the alcohol itself, and assorted fermentation byproducts called congeners (Vally and Misso, 2012, Gastroenterology and Hepatology from Bed to Bench). The evidence tying sulfites to migraines specifically is weak. If wine reliably gives you a headache, the sulfite story is the convenient answer, not the well-supported one.

The Real Risk: Asthma and Sulfite Sensitivity

There is a genuine hazard here. It is just narrower than the label panic suggests. A small subset of people react to sulfites, and the reaction can be serious: flushing, hives, stomach upset, and in the most sensitive, wheezing or a full asthma attack. The FDA estimates that roughly 1 in 100 people are sulfite-sensitive, and sensitivity is much more common among people who already have asthma (Vally and Misso, 2012, Gastroenterology and Hepatology from Bed to Bench). People without asthma rarely react.

This is not hypothetical. In the early 1980s, sulfites sprayed on restaurant salad bars to keep lettuce looking crisp and fresh were linked to severe reactions and several deaths, nearly all in people with asthma. In 1986 the FDA banned sulfites on fruits and vegetables meant to be sold or served raw, which is why you will not find them on salad bar greens or fresh produce today (FDA, 1986). They stayed legal, with labeling, in foods where people expect them, such as wine, dried fruit, and a long tail of processed products.

If you have asthma and notice symptoms after sulfite-heavy foods, that is worth a conversation with your doctor rather than self-diagnosis from a label. Reactions vary a lot from person to person, and the exact mechanism is still not fully pinned down. That careful posture is also why this page carries a caution verdict rather than a clean pass.

Reading the Label

In the US, any food with added sulfites at 10 ppm or more has to declare them, and they cannot hide inside natural flavors or a generic catch-all term (FDA, 21 CFR 101.100). The same threshold applies to standardized foods like wine and certain processed products (FDA, 21 CFR 130.9). Names to watch for, beyond the word sulfite itself:

• Sulfur dioxide
• Sodium sulfite
• Sodium bisulfite or potassium bisulfite
• Sodium metabisulfite or potassium metabisulfite

One common mix-up is worth clearing up. Sulfites are not the same as sulfates (the mineral salts in some mineral water and supplements), and they have nothing to do with sulfa drugs (sulfonamide antibiotics). A sulfa allergy does not mean you have a sulfite problem.

Where Sulfites Show Up

Sulfites are one of the oldest preservatives we use, and they remain on the FDA’s approved list with a labeling rule built around the people who actually react to them. For the bigger picture of how additives like this get reviewed, see our overview of how food additives are tested and approved and the basics in what food additives actually do . If you dry your own fruit at home, the sulfur step is optional, and our guide to drying fruit safely covers what that treatment does and does not change. And if you have ever wondered about the sulfite caramel in your cola, that is a different use of the same element, covered in our piece on caramel color .