Sulfites in food and wine.
Sulfites are inorganic compounds — sulfur dioxide and its salts — used as preservatives in wine, dried fruit, and processed foods. They can cause asthma exacerbation in some sulfite-sensitive individuals. They are not sulfa drugs, and an allergy to sulfa medications says nothing about whether you can drink wine.
- What they are
- Inorganic sulfur compounds: sulfur dioxide (
SO2), sodium sulfite, sodium bisulfite, potassium metabisulfite. EU codes E220–E228. - Where found
- Wine, dried fruit, processed potatoes, fruit juices, some condiments, some pharmaceuticals (notably some inhalers and injectables).
- Reaction pattern
- Asthma exacerbation in sensitive individuals; rare true IgE allergy.
- Relationship to sulfa drugs
- None — different chemistry, different mechanism.
What sulfites are
Sulfites are inorganic compounds derived from sulfur dioxide (SO2). Common forms include sulfur dioxide gas itself, sodium sulfite (Na2SO3), sodium bisulfite, and potassium metabisulfite. They have antioxidant and antimicrobial properties, which is why they are used as preservatives.
Sulfites occur naturally in wine as a byproduct of fermentation in small amounts; they are also added during winemaking and bottling to preserve flavour and prevent oxidation. They are added to dried fruit (apricots, raisins, prunes — sulfites are why sun-dried apricots stay orange rather than turning brown), to some processed potato products, to fruit juices, to certain condiments, and to selected pharmaceuticals as antioxidants.
The EU regulatory codes E220 through E228 cover the various sulfite preservatives. In the United States, food labels must declare sulfites above a low threshold (10 ppm), which is why "contains sulfites" appears on so many wine bottles and dried fruit packages.
Who reacts
Most people have no clinically meaningful reaction to dietary sulfites. The main population that does react comprises people with asthma, of whom a fraction (cited in various studies as around 5–10%, though estimates vary) experience worsening of asthma symptoms after sulfite exposure. The mechanism is not classic IgE-mediated allergy in most cases — it appears to involve direct airway irritation by sulfur dioxide released from the sulfite, possibly amplified by neural pathways.
True IgE-mediated sulfite allergy — with hives, swelling, anaphylaxis — exists but is uncommon. People with non-asthmatic reactions to sulfites usually describe respiratory symptoms (wheezing, chest tightness, cough) rather than the cutaneous and systemic features of typical drug allergy.
The U.S. FDA banned the use of sulfites on fresh fruits and vegetables sold raw at retail in 1986 after several deaths in asthmatic individuals exposed to high concentrations on salad bars. Sulfites in packaged foods and beverages must still be declared above the threshold.
What about wine?
Wine contains both natural and added sulfites. The amounts are typically modest — sometimes more in white wines and sweet wines than in reds, because the additional preservation needs vary. The "contains sulfites" notice required in many jurisdictions reflects regulatory thresholds, not unusually high content.
For most people, ordinary wine consumption is tolerated without reaction. People with asthma — particularly with severe or poorly controlled asthma — may notice respiratory symptoms with sulfite-rich foods or beverages and adjust intake accordingly. The widely held belief that the "morning-after wine headache" is caused by sulfites is not well supported by published evidence; histamine and other compounds in wine, and alcohol itself, are more likely contributors.
What about pharmaceutical sulfites?
Some pharmaceuticals contain sulfite preservatives. Notable examples include certain epinephrine formulations, some local anaesthetic preparations, and some inhaled bronchodilators historically. The amounts are small. Reactions to pharmaceutical sulfites are most often described in patients with known sulfite-sensitive asthma. For epinephrine specifically — a life-saving drug for anaphylaxis — sulfite content is rarely a meaningful issue, since the alternative (no epinephrine) is much worse than the small possibility of a sulfite-related effect. Modern epinephrine formulations have been reformulated in some products to reduce or eliminate sulfite.
None of this is related to sulfa drug allergy.
The four-word confusion
A short reminder, because it comes up again and again:
Sulfa = a class of drugs (sulfonamides). Sulfites = inorganic preservatives. Sulfates = inorganic salts of sulfuric acid. Sulfur = the chemical element. They share three letters and an etymology. They share little else. The disambiguation page lays it out.
What to do if you suspect sulfite sensitivity
If you have asthma and notice that wheezing or chest tightness recurs after sulfite-rich foods or wines, mention this to your asthma clinician. Avoiding the trigger and ensuring asthma is well-controlled are the practical steps. Specialist allergy evaluation can clarify the picture if symptoms are persistent or severe. None of this is medical advice — the points are general.