The following links can help you to search for any medication, including brand and generic names, drug to drug interactions, side-effects and appropriate dosages.

http://www.nlm.nih.gov/medlineplus/druginformation.html
http://www.mayoclinic.com/health/drug-information/DrugHerbIndex
http://www.healthtouch.com/bin/EContent_HT/drugInfo.asp?cid=HT
http://www.drugs.com/