I found a capsule in my son's room and do not know what it is. Can you please help? It is either yellow & white or peach & white and is marked with ETHEX 041. Any help will be greatly appreciated.

Check this site. Is this what it looks like?

ethex 041 - Pill Identification Wizard | Drugs.com (http://www.drugs.com/imprints.php?action=search&imprint=ethex+041&shape=&color=&I1=Search)