Sulphite allergy

How common is Sulphite sensitivity?

If you’re not asthmatic, sulphite sensitivity would be very unusual. However if you do have asthma, your chances of being sensitive to sulphites is in the range of between 1 in 40, and 1 in 100.

Symptoms of an allergic reaction to sulphites mostly come from breathing in the sulphur dioxide that comes from sulphite-containing foods you eat or drink and include:

• headache
• rash
• hives
• swelling of the mouth and lips
• wheezing or trouble breathing
• asthma attack (in people with asthma)
• anaphylaxis

Sulphites are chemicals used as preservatives in foods and beverages during preparation, storage and distribution. They occur naturally in wine during fermentation and have been used in wine making for centuries, to help the process along. If you have a sulphite allergy but enjoy a tipple, you’ll find organic wine is generally sulphite-free. Check the label, as it’s now mandatory to display the warning “Contains Sulphites” if they’ve been added to the wine.

Sulphites are also found in dried apricots, potato and prawn products, and are also used in the pharmaceutical industry. Sulphites are added to many medications, ironically including some of the medications given to treat asthma and allergic reactions.

If you have sensitivities, you should avoid food or drink products containing sulphites and check for these sulphite-containing ingredients on the label of your medication:

• sulphur dioxide
• potassium bisulphate
• potassium metabisulphite
• sodium bisulphite
• sodium metabisulphite
• sodium sulphate

How is a sulphite sensitivity diagnosed?

Your doctor may suspect sensitivity to sulphites based on your medical history and aspects of your asthma. The diagnosis of sulphite sensitivity can be confirmed by a "challenge" in which sulphite is administered in solutions or capsules of increasing concentration.

The challenge is done in a step-by-step fashion. Small doses of sulphite are used, so the asthma reaction that happens is usually mild. In most cases, the initial solution dose is too small for the sulphite-sensitive person to react, so increasing doses are administered, waiting 20 to 30 minutes between steps. Once a reaction takes place, it’s measured by lung function  (or spirometry)  and can be quickly reversed with an inhaled bronchodilator medication. The entire challenge procedure takes less than 2 to 2-1/2 hours.