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Methionine, Sulfa, & Sulfur

Methionine is a sulfur-containing essential L-amino acid that is important in many body functions.
The presence of sulfur in methionine has been a source of some confusion for people who are concerned about reactions to SULFA and/or SULFITES.

Sulfa-containing medications, such as the antibiotic Bactrim, are a common source of drug allergies.
These drugs contain sulfonamide, a molecule composed of sulfur, oxygen, nitrogen, and hydrogen. The allergic reaction to these drugs is not due to the chemical make up of sulfonamide, but rather the mechanism of action of sulfa-containing antibiotics. Even if you’re allergic to antibiotics that have sulfa, you might be able to take some other types of sulfa drugs without a reaction. Allergy to sulfonamides also does not imply cross-reactivity with sulfites or elemental sulfur.

Sulfites are naturally occurring molecules made up of sulfur and oxygen. Usually found in red wines, sensitivity to sulfites can cause allergy-like reactions in some people.

Sulfur is an essential element of life. Sulfur is found in amino acids and other important molecules in the body.

Usually when someone says they are allergic to sulfur, they are referring to SULFA or SULFITES, not SULFUR.

See these references for more information:
‘Sulfur allergy’ label is misleading:
Sulfite sensitivity: