Allergies to sulfonamides, also known as sulfa, are common. Sulfa drugs were the first successful treatment against bacterial infections in the 1930s. Today, sulfonamides are still used in antibiotics, as well as a host of other medications such as diuretics and anticonvulsants.  Nearly 3 percent of people are sensitive to sulfonamides. Because of the prevalence of sulfa allergies, doctors must use care when prescribing them to patients. Those with HIV/AIDS are at particular risk for sulfa sensitivity.

People often confuse sulfa with another compound that begins with letters “s-u-l-f.” Sulfites, which occur naturally in most wines—and are used as a preservative in other foods—are chemically unrelated to the similarly named medications. In fact, perhaps the only other thing sulfites and sulfas have in common besides their names are their ability to cause allergic reactions in large numbers of people. Sulfites are the ninth most common food allergen (behind milk, egg, peanuts, tree nuts, wheat, soy, fish, and shellfish).

Approximately 1 percent of people (mostly asthmatics) are sensitive to sulfites.

Sulfa Allergy Symptoms

Symptoms of an allergic reaction to sulfa include:

  • hives
  • swelling of the face, mouth, tongue, and throat
  • drop in blood pressure
  • anaphylaxis (a severe, life threatening reaction that requires immediate medical attention)

Very rarely, a patient may exhibit serum sickness-like reactions around 10 days after treatment with a sulfa drug begins. These symptoms include:

  • fever
  • skin eruptions
  • hives
  • drug-induced arthritis
  • swollen lymph nodes

Patients with the above symptoms should contact a healthcare provider immediately. 

Sulfite Allergy Symptoms

A person who is allergic to sulfites may experience the following symptoms:

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

People who experience more serious symptoms of a sulfite allergy should contact a healthcare provider. In the case of anaphylaxis, a person will require emergency medical attention.

Sulfa Medications to Avoid

The following medications should be avoided for those with allergies or sensitivities to sulfa:

  • antibiotic combination drugs such as trimethoprim-sulfamethoxazole (Septra, Bactrim) and erythromycin-sulfisoxazole
  • Crohn's disease, ulcerative colitis, and rheumatoid arthritis drug sulfasalazine (Azulfidine)
  • the leprosy drug Dapsone (also used to treat dermatitis and certain types of pneumonia)

Medications Containing Sulfa That May Be Safe

Not all drugs that contain sulfonamides cause reactions in all people. Many people with sulfa allergies and sensitivities may be able to safely take the following medications:

  • some diabetes medications including glyburide (Glynase, Diabeta) and glimepiride (Amaryl)
  • non-steroidal anti-inflammatory drugs such as celecoxib (Celebrex)
  • migraine medication sumatriptan (Imitrex, Sumavel, and Dosepro)
  • some diuretics including hydrochlorthiazide (Microzide) and furosemide (Lasix) 

Sulfite-containing Products to Avoid

It’s important to note that most groups aren’t sensitive to sulfites, except one—those with asthma. Asthma sufferers have between a 1 in 10 and 1 in 20 chance of having a reaction to sulfites.

Not only do sulfites occur naturally in wines during fermentation, but many winemakers add them to help the process along. For the past two decades, the U.S. Food and Drug Administration (FDA) has required winemakers to display the warning "contains sulfites" if levels exceed a certain threshold. Many companies voluntarily add the label to their products as well.

Individuals with sensitivities should avoid food products with sulfur dioxide, potassium bisulfate, potassium metabisulfite, sodium bisulfite, sodium metabisulfite, and sodium sulfite on the label. Sulfites are common in the following foods and ingredients:

  • alcoholic beverages including white and red wines and wine coolers
  • baked goods containing dried fruit and vegetables
  • beverage bases that include dried citrus fruit
  • condiments such as pickles, olives, horseradish, pickle and onion relishes, wine vinegar, and salad dressing mixes
  • cornstarch, modified food starches, spinach pasta, some gravies, hominy, certain breading, batters, and noodle and rice mixes.
  • dried fruit snacks including trail mixes and peanut butter or cheese filled crackers as well as maraschino cherries and glazed fruits
  • fish and shellfish such as fresh, frozen, canned or dried shrimp, dried cod, scallops, frozen lobster, and canned clams
  • fruit fillings, flavored and unflavored gelatin, and pectin gelling agents
  • fruit juices (canned, bottled, or frozen) including lemon, lime, grape, and apple
  • jams and jellies
  • shredded coconut
  • soups containing seafood or dried soup mixes
  • sugars including brown, powdered, raw, or white sugar derived from sugar beets
  • sweet sauces including anything with high-fructose corn syrup, maple syrup, and fruit toppings
  • teas that are either instant or made from liquid concentrates
  • any product containing potatoes and vegetables that are pickled or dried