Tramadol is an opioid pain reliever. Its plasma half-life is between 6 and 7 hours, which means that it takes that amount of time for the concentration of Tramadol in the blood to be reduced by half. More more in-depth information about Tramadol, you can visit here: http://opioids.com/tramadol/prescribe.html
It depends on the dose you are on but it can usually stay in your system up to two weeks or longer. It is occasionally taken as directed by your physician a single dose can work up to 7 hours. Your tolerance to medication plays a vital role in how much, how often this type of medication is needed.