The general rule of thumb is that you should not take products like Tylenol PM for more than 14 days. If you have been taking this for more than that, I would advise making an appointment with your doctor or healthcare provider for further evaluation. With continued use you may experience "rebound insomnia" which means you get a version of insomnia that can be much worse, or you could even develop a tolerance to Tylenol PM (which means no matter how much you take, it will not work). Another important issue is that you may be experiencing side effects like dry mouth, dizziness, and constipation, which could lead you to using additional medications to treat those side effects -- which would not be necessary if you were not taking the Tylenol PM.
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