I use these patches every time I go on a cruise, which is usually once to 3 times a year and usually a 7 to 10 day cruise each time. When I use them my mouth gets very dry and I have to use only 1/2 a patch every 3 days. Every since I started using them my mouth and eyes have been dry. I don't take any other meds. I am 58 years old and its been happening approx 3 years. I have no other medical problems and very active and healthy.