How long does kava stay in your system? would it have a half life like a prescription drug?

Depends: It depends. Effects can last up to 12 hours; metabolites can stay in your system for up to 2 weeks. At most use one kava capsule three times a week and take a full week off each month. it is preferable to use kava no more than two times a week. Kava use on a daily basis can harm the liver. In rare cases, daily kava kava use can lead to severe liver harm: may result in total liver failure.