There is a silent but debilitating form of corruption going on in many jurisdictions which involves supplying expired or fake medicine to private institutions to sell over the counter. I don't think its reliable to check the expiry date as some of these dates are false. I have heard of an app or an appliance to scan the veracity of such but what do you do in your case?
I think that to avoid being scammed by such merchants then we should always just buy our medicines from reputable drug stores and we should buy them in person. I think large stores would think twice about selling the public fake medicines, because it would hurt their business and company reputation.
I'm not sure where you live, but there are very tight regulations in most countries. The grey area is online medication as that is harder to detect, but if people choose to buy that way then they must be very careful and aware that there are many fake items or indeed illegal medicines. The general rule is, only buy from reputable companies. It may cost more but will be safer in the long run.
I agree, the expiry dates on the drugs could be falsified to make it look still relevant. One surer way to ascertain if a medicine is fake would be to attach codes to every sachet of the drugs from the drug regulatory body of that jurisdiction. There should be a way to text the code to a number controlled by this body to verify drug authenticity.
There are many ways for makers/sellers of fake medicines to infiltrate the market and ordinary consumers are just helpless when it comes to identifying the fakes from the real. Even generic meds are being faked these days. That is why I would always make it a point to buy from reputable drugstores where medicines are kept in the optimum temperature. In addition, these drugstores have strong internal control system which makes it difficult or impossible for their employees or management to profit from illegal trades such as selling expired or fake drugs.
It is too risky and dangerous to buy an expired medicines. We have various drug stores here in our place and they are all license and they never sell to the public a "fake" medicine which is not duly approved by the Food and Drug Administration and as recommended by the Department of Health. There are ambulant drug vendors roaming around the city and they are selling affordable medicines, but we never dare to buy from them even it is OTC medicines and approved by the FDA. We couldn't hold them liable when something happens to us after using their medicines sold.