How long will 10mg of valium taken twice stay in my system?

Quite a while: The "half life of elimination" of Valium (diazepam) plus its active metabolites ranges from 40 to 100 hours - depending on the individual. The the rule of thumb in pharmacokinetics is that it requires 5 half lives for a drug to reach negligible levels. So, the estimate would be from 200 to 500 hours to completely eliminate diazepam from the human body.

Stays for a while: Valium is a long acting drug that can have an effect in the body for up to 24 hours. In terms of detection in the body systems, the drug can be detected between 2-48 hours in saliva, 5-7 days for short-term use or 4-6 weeks for chronic use in the urine, and up to 90 days in the hair. These findings are estimates as test results can still be positive outside of these ranges based on several factors