Sulfite Allergy Overview and Foods to Avoid

The food additive that can trigger asthma symptoms

Sulfite Allergy Overview and Foods to Avoid

Illustration by Joshua Seong Verywell, 2018. 

Sulfites have been used for centuries, mainly as food additives to enhance flavor and preserve freshness. But these sulfur-based compounds also occur naturally in foods, such as fermented beverages and wines. They're also used as a preservative in a variety of medications to help increase shelf life.

Examples of sulfites include:

  • Sodium sulfite
  • Sodium bisulfite
  • Sodium metabisulfite
  • Potassium bisulfite
  • Potassium metabisulfite
  • Sulfur dioxide

Exposure to sulfites can cause a host of adverse effects in sensitive people, ranging from mild to potentially life-threatening. Here's how a sulfite allergy is diagnosed and how you can prevent a reaction if you've been diagnosed with this allergy. 

Overview

The good news is that sulfites usually don't cause problems in people without allergies and asthma, even when large amounts are consumed. However, in 5 to 10 percent of people with asthma, sulfites are known to increase asthma symptoms like wheezing, chest tightness, and coughing. This usually occurs in adults with severe and/or poorly controlled disease. Numerous well-controlled studies show that some asthmatics can have severe asthma symptoms after eating sulfite-containing foods/beverages or inhaling sulfite fumes or vapors.

Less is known about developing hives/swelling and anaphylaxis as a result of sulfites, although various cases have been described in which consuming sulfite-containing foods/beverages led to severe allergic reactions. Some of these people even had positive skin tests for sulfites, suggesting allergic antibodies to the preservative were present.

Other people have experienced severe reactions from sulfite-containing medications, including intravenous drugs and inhaled medications. These reactions included flushing, hives, and a drop in lung function as a result of taking the medications.

Sulfites don't appear to be a culprit in people suffering from repeated episodes of anaphylaxis of unknown cause. They're also not a risk for anaphylaxis in people with mastocytosis, a rare disorder caused when an excessive number of mast (immune) cells gather together, and appear to present little to no risk for people without asthma and without atopy, the genetic tendency to develop allergic diseases.

Causes

It’s not completely known how sulfites cause reactions in certain people. Some people clearly make allergic antibodies against sulfites, while others do not. The gasses generated from sulfites might cause muscle spasms in the lungs of some asthmatics, or the reaction could be related to the inability of some people to metabolize the sulfites appropriately.

Diagnosis

While there have been some case reports of people being diagnosed with sulfite allergy using skin testing, there's no reliable, commercially available skin test for sulfite allergy. Typically, the diagnosis is suggested by a history of adverse reactions after consuming sulfite-containing foods or medications.

In order for the diagnosis to be confirmed, an allergist may perform an oral challenge for a patient suspected of having a sulfite allergy. This procedure involves giving a person increasing amounts of sulfites to swallow while closely monitoring lung function and vital signs. A significant drop in lung function confirms sensitivity to sulfites.

This test should only be performed under the direct supervision of a physician who's been trained and is experienced with this procedure.

Why Sulfites Are Added to Foods

Sulfites are added to foods for various reasons. These include:

  • Reducing bacterial spoilage
  • Slowing the browning of fruit, vegetables, and seafood
  • Inhibiting growth of bacteria during fermentation of wines
  • Conditioning of dough in frozen pie and pizza crust
  • Bleaching effect for maraschino cherries and hominy

In the past, sulfites were added to fresh foods in restaurants and grocery stores to prevent browning. An increase in reactions led the Food and Drug Administration (FDA) to ban the use of sulfites in fresh foods in 1986, particularly on fresh lettuce in salad bars.

The FDA now requires that any food containing more than 10 parts per million (ppm) concentration of sulfites to be declared on the label. This is because foods that contain less than 10 ppm of sulfites have not been shown to cause symptoms, even in people allergic to sulfites.

Foods That Contain Sulfites

There are a number of foods that contain sulfites.

Greater than 100 ppm of sulfites (very high levels; strict avoidance advised in people with sulfite allergy)

  • Dried fruits (excluding dark raisins and prunes)
  • Bottled lemon juice (non-frozen)
  • Bottled lime juice (non-frozen)
  • Wine
  • Molasses
  • Sauerkraut (and its juice)
  • Grape juices (white, white sparkling, pink sparkling, red sparkling)
  • Pickled cocktail onions

Between 50 and 99.9 ppm of sulfites (moderate to high levels of sulfite; avoidance advised in people with sulfite allergy)

  • Dried potatoes
  • Wine vinegar
  • Gravies/sauces
  • Fruit toppings
  • Maraschino cherries

Between 10 and 49.9 ppm of sulfites (low to moderate levels of sulfite, may cause symptoms in people with severe sulfite allergy)

  • Pectin
  • Fresh shrimp
  • Corn syrup
  • Pickled peppers
  • Pickles/relish
  • Cornstarch
  • Hominy
  • Frozen potatoes
  • Maple syrup
  • Imported jams and jellies
  • Fresh mushrooms
  • Imported sausages and meats
  • Cordials (alcoholic)
  • Dehydrated vegetables
  • Various cheeses
  • Cornbread/muffin mix
  • Canned/jarred clams
  • Clam chowder
  • Avocado dip/guacamole
  • Imported fruit juices and soft drinks
  • Ciders and cider vinegar

Less than 10 ppm of sulfites (very low sulfite levels, generally do not pose a risk, even for people with sulfite allergy)

  • Malt vinegar
  • Canned potatoes
  • Beer
  • Dry soup mix
  • Soft drinks
  • Frozen pizza and pie dough
  • Beet sugar
  • Gelatin
  • Coconut
  • Fresh fruit salad
  • Domestic jams and jellies
  • Crackers
  • Cookies
  • Grapes
  • High fructose corn syrup

Medications That Contain Sulfites

Sulfites are added to some medications for their antioxidant properties as well as to prevent browning (discoloration) of medications. Sulfites are added to injectable epinephrine (for example, the EpiPen) to prevent browning, which decreases the effectiveness of the drug.

However, epinephrine has not been reported to cause adverse reactions in people with a sulfite allergy and should not be withheld in an allergic emergency. Injectable epinephrine may prove life-saving in people with a sulfite allergy who are experiencing anaphylaxis.

Some inhaler solutions used to treat asthma contain sulfites, although many asthma drugs have had sulfites removed due to safety concerns. People with a sulfite allergy should avoid medications containing sulfites, except for injectable epinephrine (for example, EpiPen and Twinject).

Here are examples of medications that contain sulfites:

Bronchodilator solutions for asthma

  • Adrenalin chloride 1:1000 concentration (epinephrine)
  • Bronkosol (isoetharine)
  • Isuprel (isuprel hydrochloride)

Topical eye drops

  • Bleph-10 (sulfacetamide sodium)
  • AK-Dex, Ocu-Dex (dexamethasone)
  • Pred-Forte (prednisolone acetate)
  • Pred-Mild (prednisolone)

Injectable medications

  • Adrenaline, Ana-Kit, EpiPen (epinephrine)
  • A-Hydrocort, Solu-Cortef (hydrocortisone-injectable)
  • Amikin (amikacin)
  • Aramine (metaraminol)
  • Celestone (betamethasone phosphate)
  • Compazine (prochlorperazine) 
  • Decadron (dexamethasone phosphate)
  • Demerol (meperidine)
  • Dopamine
  • Garamycin (gentamycin)
  • Isoetharine HCl
  • Isuprel (isoproterenol-injectable)
  • Levophed (norepinephrine)
  • Nebcin (tobramycin)
  • Novocaine (procaine)
  • Phenergan (promethazine) 
  • Solutions for total parenteral nutrition and dialysis
  • Thorazine (chlorpromazine) 
  • Xylocaine with epinephrine (lidocaine with epinephrine)

Prevention and Treatment

Generally, people with a known or suspected sulfite allergy should avoid foods and medications that contain sulfites. This should be relatively easy to accomplish, given the mandate by the FDA to label foods containing 10 ppm or more of sulfites.

Avoiding sulfites may be trickier in restaurants though. While the FDA's ban on sulfites from fresh fruits and vegetables in restaurants (such as in salad bars) has significantly reduced the risk of accidental ingestion of sulfites, unlabeled sulfite-containing foods remain in restaurants, with sulfites in potatoes considered a major concern. For this reason, people allergic to sulfites should avoid all potato products when eating out, except for baked potatoes with the skin intact.

If an allergic reaction develops after a sulfite-containing product is consumed, that specific reaction needs to be treated. For example, while asthma symptoms may require the use of inhaled bronchodilator solutions (those that don't contain sulfites), a severe allergic reaction and anaphylaxis may require treatment with injectable epinephrine. On this note, it's important for people with severe sulfite allergy to carry injectable epinephrine (EpiPen or Twinject) and to obtain a Medic-Alert bracelet

A Word From Verywell

Sulfite allergies are uncommon and mostly seen in people with severe asthma. If you have asthma, you shouldn't necessarily avoid sulfite-containing foods, unless you and your doctor suspect that you have a sulfite allergy or you've been diagnosed with one.

View Article Sources
  • Sampson HA et al. Food allergy: a practice parameter update-2014J Allergy Clin Immunol. 2014 Nov;134(5):1016-25.e43.
  • U.S. Food & Drug Administration. (2013). Guidance for Industry: A Food Labeling Guide (6. Ingredient Lists).