Allergies to sulfonamides, also known as sulfa drugs, are common. Sulfa drugs were the first successful treatment against bacterial infections in the 1930s. They’re still used in antibiotics today. They’re also used in other medications, like diuretics and anticonvulsants.
Nearly 3 percent of people are sensitive to sulfonamides. Sulfa allergies are common. People with HIV/AIDS are at particular risk for sulfa sensitivity.
People often confuse sulfa with sulfites. Sulfites occur naturally in most wines. They’re also used as a preservative in other foods. They’re chemically unrelated to sulfa medications. Besides similar names, sulfa and sulfites share an ability to cause allergic reactions in large numbers of people.
Sulfites are the ninth-most common food allergen. Approximately 1 percent of people, mostly people with asthma, are sensitive to sulfites.
Symptoms of an allergic reaction to sulfa include:
- swelling of the face, mouth, tongue, and throat
- drop in blood pressure
- anaphylaxis (a severe, life threatening reaction that requires immediate medical attention)
Rarely, cases of serum sickness-like reactions can occur around 10 days after a sulfa drug treatment begins. Symptoms include:
- skin eruptions
- drug-induced arthritis
- swollen lymph nodes
You should contact a doctor immediately if you have these symptoms. Avoid the following medications if you’re allergic or have a sensitivity to sulfa:
- antibiotic combination drugs such as trimethoprim-sulfamethoxazole (Septra, Bactrim) and erythromycin-sulfisoxazole
- sulfasalazine (Azulfidine) used for Crohn's disease, ulcerative colitis, and rheumatoid arthritis
- Dapsone (used to treat leprosy, dermatitis, and certain types of pneumonia)
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 (NSAIDs) such as celecoxib (Celebrex)
- migraine medication sumatriptan (Imitrex, Sumavel, and Dosepro)
- some diuretics including hydrochlorthiazide (Microzide) and furosemide (Lasix)
Symptoms of an allergic reaction to sulfite include:
- swelling of the mouth and lips
- wheezing or trouble breathing
- asthma attack (in people with asthma)
If you experience more serious symptoms of a sulfite allergy, contact your doctor. Anaphylaxis requires emergency medical attention.
According to the Cleveland Clinic, people with asthma have between a 1 in 10 and 1 in 20 chance of having a reaction to sulfites.
Sulfites are common in, processed foods, condiments, and alcoholic beverages, such as red and white wine. Sulfites occur naturally in wine during fermentation, and many winemakers add them to help the process along. For the past two decades, the U.S. Food and Drug Administration 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.
People with sensitivities should avoid food products with the following chemicals on the label:
- sulfur dioxide
- potassium bisulfate
- potassium metabisulfite
- sodium bisulfite
- sodium metabisulfite
- sodium sulfite
Work with your doctor to determine the best course of action if you suspect you have a sulfa or sulfite allergy. You may need to see a specialist or undergo further testing. Be sure to talk to your doctor about which medications and products to avoid, especially if you have asthma.