What happens if you take too much blood pressure medicine?

Wrong question: The main question should be "what happens if you have uncontrolled hypertension?", and for that I could have a short or long answer, but you did not ask. It does not make any difference how many medications you take to control hypertension as long as the BP is well controlled and you do not have many side effects.

Overdose?: Depends upon the type of blood pressure medication. All can cause low blood pressure - and - Generally with the beta blockers and calcium channel blockers you can see very low heart rates and syncope. Overdose of diuretics can cause dehydration and kidney damage. Overdose of ACEI / ARB can cause kidney damage. There are many other meds to be considered but not enough space to detail here.