You see “contains sulphites” on every bottle of wine that contains more than 10 parts per million (ppm) of sulphites or 10 milligrams per litre. It is necessary to label wines such, as it is estimated that around 1% of people have some sort of allergy to Sulphites. Severe asthma sufferers are particularly prone as are people without the necessary enzymes to break down Sulphur Dioxide.
Sulphites often are blamed for a headache after drinking wine, however that maybe misleading, as tannins, histamines and, of course, the alcohol are also prime suspects.
Sulphur Dioxide, to which “Sulphites” refers, is a naturally occurring bi-product of the fermentation process during winemaking, so all wine contains some sulphites at a level of about 10 ppm before additional sulphites are added. Therefore, nearly every bottle of wine you come by has the Sulphites warning.
Sulphur Dioxide is widely used in the food industry as a preservative at much greater levels than those used in the Wine industry. For example, dried fruits contain up to ten times the number of Sulphites than that of the average bottle of wine.
Sulphites are added by the wine maker to stabilise and preserve the wine and make the wine more consumer friendly. Generally, less sulphites are added to red wine than white, rosé or dessert wines as tannins in the red wine act as a natural stabilizing and aging agent. Dry and delicate white wines require more sulphites to preserve them
Occasionally you will see the phrase “No added Sulphites” on a wine label. This means that there are natural sulphites contained in the wine, however the Winemaker has not added additional Sulphur Dioxide.
As a guide the upper limits on wine are Red Wine 150 parts per million (150mg per litre)200ppm for white and Rosé and up to 400 ppm for dessert wine.
If you want avoid Sulphites it is best to stick with Organic, Biodynamic or natural wines where the upper levels of sulphur are controlled and are included in the certification.
If you want to further reduce the effects of sulphites, open and decant your wine 20 minutes before consumption to allow some of the sulphites to be released into the atmosphere.
To find out more there is a good article in this link: