A campaign against counterfeit medicines was launched on 25 October 2011. For two weeks (until 5 November), you can have medicines you bought online checked in over 750 pharmacies in Switzerland, free of charge. Your pharmacist will help you to identify questionable medicines from illegal sources.
You can find the list of pharmacists taking part in the campaign here.
And by the way: there have never been any counterfeit medicines discovered at the legal dispensing points in Switzerland (pharmacies, drugstores, hospitals, physicians' practices).