Hello Cmille Whitely
As the other expert is offline, may be I can try to help you out.
Well diovan is known to cause dizziness and thus your doctor prescribed you with another drug. The half life of Diovan is about 6 hours. Half life of a drug is defined as the time it takes fot the concentration of the drug to be reduced to half in the body and thus doubling this time would lead to the amount of time in which the whole of the drug would be out of the body and would be loosing its affects.
So approximately the time it would take for the drug(Diovan) to get out of your system would be around 12-14 hours.
Its highly recommended that you donot alter the dosage of the drugs as advised by your doctor and should be starting on the bystolic as your doctor has advised.
Hopefully this was helpfull enough and do ask for any further assisstance