I’ve never heard that. Seems an arbitrary number. Where did you hear this?
I have been taking it since 2009. Still works.
Sometimes I think people can build a tolerance, even though doctors will say no. Sometimes meds do stop working. But it’s not in “X” years. It could be anytime, or never.
I’ve heard that too n then they increase the dose
I was on it for a long time and I never heard that