dry eye disease
"Helps dry eye - but generates Terrible long-lasting bitter taste in the mouth, that stays for 4-6 hours or even more) and makes Every food or drink taste bad. 
I called Shire and they know that this is an effect of the drug - but they have no Idea what causes it or how to counter it. So - we cannot even know for sure that this is not a long-lasting damage to the taste bud or to any other important function. The longest clinical trials were for 12 months. Thus any long-lasting damage is not known. The thought is troublesome and so is that bitter taste."