So the correct answer to your question would be it takes at least 8-10 days for it to be out of your system. It's a benzo with a longer half life like Valium and Librium. It's a benzo with a longer half life like Valium and Librium. How Long Does Klonopin Stay in Your System? Many people who are thinking of getting sober wonder how long Klonopin will stay in their system. To determine how long it will remain in your system after your final dose, it’s important to consider the half-life of Klonopin’s active ingredient, clonazepam. Find out how long Ativan (lorazepam) can stay in your system, and learn about precautions and things to avoid while taking it. Lorazepam is the generic name for a benzodiazepine medication sold under the brand name Ativan. This medication is prescribed to treat anxiety, including anxiety associated with depression and panic disorders. Klonopin's half-life is 18-50 hours. A drug leaves your system after 5 half-lives, thus, Klonopin should be out of your system in 2-3 days. However, half-life is affected by dose, as well, and 2mg is not a huge dose but it's a moderate one. Since clonazepam is speculated to be metabolized by CYP3A4 isoenzymes, drugs that affect CYP3A4 function may affect how long it stays in your system. Certain drugs, known as “inhibitors” of CYP3A4, interfere with isoenzymes responsible for metabolizing clonazepam. Therefore, it might stay in your system as long as 250 hours depending on various factors. Doctors give trusted answers on uses, effects, side-effects, and cautions: Dr. Ali on how long do clonazepam stay in your system: The half life of Clonazepam is as long as 50 hours. How long does klonopin stay in your system, blood, saliva, urine etc Drugs in your body are eliminated through various means. They can be eliminated through the urine, saliva and sweat. How long does Clonazepam stay in your system? If I took half of a 2mg Clonazepam will it show in a urine test 7 days from the time I took it? I am not a regular user this is the first time I have taken one in over a year.