Sulfa Drug Allergy

One of the more common drug allergies is that to sulfa drugs. Sulfa drugs are more appropriately labeled sulfonamides and are derivatives of para-amino benzoic acid. The following list contains common medications that have a sulfonamide component. A sulfonamide allergy is different from a sulfite allergy because sulfonamides and sulfites are distinctly different chemicals. A person allergic to sulfites is no more likely to be allergic to sulfonamides than any other individual.

Sulfonamide drug classes/individual drugs that may cause allergic reactions include:

Sulfonamide antibiotics, sulfadiazine, sulfamethoxazole, sulfasalazine, sulfisoxazole, sulfacetamide, sulfanilamide, sulfathiazole, sulfabenzamide, Thiazide diuretics, hydrochlorothiazide, chlorothiazide, metolazone, chlorthalidone, indapamide, methyclothiazide, Loop Diuretics, furosemide, Sulfonylureas, chlorpropamide, tolbutamide, tolazamide, glipizide, glyburide, Carbonic anhydrase inhibitor, and acetazolamide.

The mechanism of the sulfonamide drug allergy is immune mediated. When a sulfonamide is metabolized in the body, the drug is capable of attaching to human proteins, forming a larger molecule and possibly launching an immune response.

In contrast, sulfiting agents refer to a group of chemicals that include sulfur dioxide, sulfite salts, and sulfate salts. Sulfur dioxide is considered to be the offending component in a sulfite allergy. Sulfites and sulfates are metabolized to sulfur dioxide under certain conditions that depend on concentration, heat, and pH.


Signs, symptoms & indicators of Sulfa Drug Allergy

Symptoms - Allergy  

(Possible) sulfa allergy

Counter Indicators
Symptoms - Allergy  

Absence of sulfa allergy

Recommendations for Sulfa Drug Allergy


Glucosamine / Chondroitin Sulfate

See the link between Sulfa Drug Allergy and MSM.


MSM (Methyl Sulfonyl Methane)

Although it is generally believed that people who are allergic to sulfa drugs or do not tolerate sulfite preservatives in foods need not be concerned about the use of MSM and glucosamine sulfate – that these do not give rise to allergic reactions. However, there are reports of individuals who are reactive, so caution is advised.


Proven definite or direct link
Very strongly or absolutely counter-indicative
May have adverse consequences



Hypersensitivity caused by exposure to a particular antigen (allergen), resulting in an increased reactivity to that antigen on subsequent exposure, sometimes with harmful immunologic consequences.


A class of diuretics that increase the excretion of sodium and chloride and accompanying volume of water.


An agent increasing urine flow, causing the kidneys to excrete more than the usual amount of sodium, potassium and water.


Compounds composed of hydrogen, oxygen, and nitrogen present in the body and in foods that form complex combinations of amino acids. Protein is essential for life and is used for growth and repair. Foods that supply the body with protein include animal products, grains, legumes, and vegetables. Proteins from animal sources contain the essential amino acids. Proteins are changed to amino acids in the body.


A measure of an environment's acidity or alkalinity. The more acidic the solution, the lower the pH. For example, a pH of 1 is very acidic; a pH of 7 is neutral; a pH of 14 is very alkaline.

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