Charlie Sheen -- Clean As a Whistle

3/22/2011 8:00 AM PDT

Charlie Sheen -- Clean As a Whistle

Charlie Sheen is high on life -- and tiger blood -- but he's not high on drugs ... TMZ has learned. 

As TMZ first reported, Sheen and his ex, Brooke Mueller, each took drug tests back on March 11 as part of their custody settlement.

Sources close to the couple tell TMZ that Sheen got his results back within the last few days -- he passed. No word yet on Mueller's results.

The drug test clears the way for Charlie to see his children again, we're told, with a monitor present.