condroitin sulfate--sulfur allergy?

[sassy]

My mother-in-law is considering taking glucosamine/condroitin for arthritis, but has a sulfer allergy and is concerned about the condroitin sulfate. She could take the glucosamine without condroitin, but it would be less effective.

Does anyone know anything about the condroitin sulfate chemistry? I too have a sulfur allergy and have been taking glucosamine/condrotin for over two years with no obvious reaction.

Thanks for any input.