Can chitosan cause allergies?
Earlier reports had suggested that chitosan may be able to cause allergies in persons with a shellfish allergy, but we know today that these reported cases were caused by protein impurities present in the chitosan used. Pure chitosan does not cause allergies. In fact, chitosan is not even recognized by our immune system (the first step in the formation of allergies), possibly due to its chemical similarity to glycosaminoglycans, i.e. N-acetylglucosamine-containing polysaccharides naturally occurring in our body. This near invisibility of chitosan to the immune system is also the reason why anti-chitosan antibodies are not easily raised. Of course, this is also one of the reasons for chitosans' biocompatibility which makes them suitable for biomedical applications.