Thiomers are capable of forming disulfide bonds with cysteine substructures of the mucus gel layer covering mucosal membranes. Because of this property they exhibit up to 100-fold higher mucoadhesive properties in comparison to the corresponding unthiolated polymers. Because of their mucoadhesive properties, thiolated polymers are an effective tool in the treatment of diseases such as dry eye, dry mouth, and dry vagina syndrome where dry mucosal surfaces are involved.