Accidently took extra dose of verapamil 240mg, how do i treat this?

A single dose?: If you just took a single extra dose, you don't require any specific treatment. Just lie low today as your blood pressure and heart rate may be a bit slower than usual and you may be somewhat more prone to dizziness. Depending on the formulation you use, it will wear off in 8 to 24 hours. If don't feel well, of course, you should go to the ER.