Druglib.com – Drug Information
‘DrugLib.com is a comprehensive drug database organized by relevance to specific drugs. It provides a convenient, one-stop access to a wide range of information related to your drug of interest, including drug label & prescribing information (description, clinical pharmacology, side-effects, indications, warnings, etc.), published studies, current clinical trials, alerts and news.’
Seems like a good starting place for any information regarding common prescription medications.