Sulfa allergy: Which medicines should I avoid?

People who have a sulfa allergy can react to antibiotics and other medicines that contain a chemical called sulfonamide (suhl-FON-uh-mide).

Sulfonamide antibiotics that can cause a reaction

A number of antibiotics containing sulfonamides can trigger a reaction if you have a sulfa allergy.

• Sulfamethoxazole-trimethoprim (Bactrim, Septra) is taken as a pill. The brand name for a children’s syrup is Sulfatrim Pediatric.
• Silver sulfadiazine (Silvadine, SSD, Thermazine) is an antibiotic cream used to treat and prevent wound infections in burns.
• Sulfacetamide (Klaron) is an antibiotic lotion.
• Sulfacetamide-prednisolone is an antibiotic eye drop.

Other medicines likely to cause a reaction

Similar medicines likely will trigger a reaction in people who have a sulfonamide antibiotic allergy.

• Sulfasalazine (Azulfidine), is used to treat Crohn’s disease, ulcerative colitis and rheumatoid arthritis.
• Dapsone is used to treat leprosy, certain skin conditions and other diseases.

Sulfonamide medicines not likely to cause an allergic reaction

You may be able to take some other medicines with sulfonamide even if you have an allergic reaction to sulfonamide antibiotics. These include:

• Certain diabetes medicines, such as glyburide (Glynase, Diabeta), glipizide (Glucotrol XL) and glimepiride (Amaryl).
• Some nonsteroidal anti-inflammatory medicines, such as celecoxib (Celebrex, Elyxyb, Vyscoxa).
• Certain migraine medicines, such as almotriptan, naratriptan, sumatriptan (Imitrex, Tosymra, others).
• A number of diuretics, also called “water pills,” that help the body get rid of excess fluids, including acetazolamide, furosemide (Furoscix, Lasix) and hydrochlorothiazide (Inzirqo, Microzide).

Always tell your healthcare professional about any known allergy to a medicine. If you have HIV/AIDS, you may have an increased sensitivity to sulfonamide medicines.

An allergy to sulfonamide medicines is different from having an adverse reaction to wine or food that contains sulfites. Having a reaction to sulfites in something you eat or drink doesn’t mean you’ll be allergic to sulfonamide medicine.

There are no diagnostic tests for sulfa allergy. Different strategies can be used to reintroduce a drug if a reaction was reported or suspected in the past.