Sulfate vs. Sulfite Allergy

Allergy to Sulfa, Sulfite, Sulfate and Sulfur

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Allergy to Sulfa, Sulfite, Sulfate and Sulfur

There is much confusion regarding allergy to sulfa-containing drugs, sulfite as a preservative agent in foods and medications, sulfate salts of medications and the chemical element sulfur. Many of my patients assume that if they are allergic to one of these agents, then they are allergic to all of them. This is not necessarily true.


Sulfa-containing medications are a common cause of drug allergy, and I think the reason for most of the confusion.

The majority of the time, a person with a sulfa allergy has experienced an allergic reaction to a sulfa-containing antibiotic, such as in Bactrim. The antibiotic sulfonamides are different structurally from the nonantibiotic sulfonamides and appear to be much more likely to result in allergic reactions. Many of the sulfa nonantibiotics, therefore, do not cause problems in people with sulfa antibiotic allergy.

Find out more about sulfa allergy, and what medications should be avoided in someone with a sulfa allergy.


Sulfites are common preservatives used in various foods and medications. Sulfites have been used for centuries, mainly as food additives, but can also occur naturally in foods such as fermented beverages and wines. Examples include sodium sulfite, sodium bisulfite, sodium metabisulfite, potassium bisulfite and potassium metabisulfite. Sulfites are best known to cause worsening breathing problems in certain people when foods or beverages containing sulfites are eaten.

Other people have experienced severe allergic reactions after eating foods or taking medications that contain sulfites.

Find out more about sulfite allergy, including what foods and medications should be avoided in someone with a sulfite allergy.

Also, learn about the treatment for sulfite allergy.


Sulfates are salts of sulfuric acid and are commonly used in the making of various drugs, such as albuterol sulfate, iron sulfate, chondroitin sulfate and codeine sulfate.

While allergic reactions to these medications are possible, it’s not likely that it’s because of the sulfate group. There does not appear to be any reason for people with sulfa or sulfite allergies to avoid medications that contain a sulfate salt.


Sulfur is a chemical element that is used in the production of countless pharmaceutical and commercial chemicals and is present in (and responsible for the names of) sulfa drugs, sulfite preservatives, and sulfates. Sulfur is too small, as an element, to cause allergic reactions by itself; therefore, there does not appear to be a reason for people with sulfa and/or sulfite allergy to specifically avoid sulfur-containing compounds.

Want to learn more? Find out about the treatment of medication allergies.


Choquet-Kastylevsky G, et al. Allergic Adverse Reactions to Sulfonamides. Current Allergy and Asthma Reports. 2002;2:16-25.

Allen J. Which Medications to Avoid in Patients with Sulfa Allergy? Prescriber's Letter. July 2000.

Chapman JA, Bernstein L, Lee RE, Oppenheimer J. Food Allergy: A Practice Parameter. Ann Allergy Asthma Immunol. 2006; 96: S1-68.

Wilson BG, Bahna SL. Adverse Reactions to Food Additives. Ann Allergy Asthma Immunol. 2005; 95: 499-507.

Bush RK, Taylor SL, Hefle SL. Adverse Reactions to Food and Drug Additives. In: Adkinson NF, Yunginger JW, Busse WW, et al, eds. Middleton’s Allergy Principles and Practice. 6th edition. Philadelphia: Mosby Publishing; 2003:1645-1663.

Lakness J. Allergy Elimination Diets. In: Lawlor GJ, Fischer TJ, Adelman DC, eds. Manual of Allergy and Immunology. 3rd ed. Boston: Little, Brown and Co;1995:559-60.

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