How long does it take for med Benicar (olmesartan) to start working and to get out of your system?

Benicar (olmesartan) onset. Benicar (olmesartan) (B) is a member of the angiotensin receptor blocker (ARB) class of drugs. It works by remodeling the endothelium (E) of blood vessels, which makes them less stiff and it lowers BP that way. It takes about 2 weeks for B to remodel the E. Once B is stopped, the E begins to change to become stiffer, or less compliant and the BP rises. So, the answer to your question is about 2 weeks.
Pharmacodynamics. The half life of Benicar (olmesartan) is 13 hours. That means it will reach steady state in about 65 hours and will take about the same amount time to wear off. That said, the usual practice is to give a new anti-hypertensive drug several weeks to have a full physiological effect.