So... I'm not a doctor, I don't play one on TV, and I have zero idea if this is what your problem is. BUT. I do know that as we age, our livers slowly become less efficient at cleaning up our blood, and over time, some medications can build up in the body to levels where they now cause side effects they didn't before. So sometimes older folks might need to reduce their dosage of some medicines a little, to stay within a therapeutic level but not cause the unwanted side effects. Don't do this on your own - ask your doctor about it.