The first question that any consumer should have when dealing with an Internet pharmacy should be whether or not said Internet pharmacy can be trusted. It doesn't take a whole lot of effort for someone to set up a fake Internet pharmacy that looks so much like a legitimate one --- a frightening but very realistic prospect. There may be more than a few organizations that can be looked towards to verify the authenticity and reliability of any given website, but just how many consumers would be aware of them? And if consumers were aware, how many average consumers have the time, patience, or even good sense to go through the records of such organizations to find a site that is convenient, legitimate, and has what they need? Statistics for this sort of thing are hard to come by, but most anecdotal evidence and the prevalence of scam sites suggests that the numbers are dismally low.
Another thing to consider would be geography. The first part of this concern involves just how long it would take for standard delivery procedures to get your order to your doorstep. Medication can be a very sensitive thing, with some conditions being so hair-trigger than even a day's delay on drug doses can result in some very dangerous side effects. If the pharmacy's warehouses are nowhere near your location, then it would likely be much healthier to just drive to the closest real pharmacy than order online. Geography also plays a role on whether or not the pharmacy of your choice may even be able to deliver the medications you orders without breaking some law or regulation. Medication that enjoy legal status in one country could easily be restricted or illegal in another. Thankfully, a vast number of sites state the limits of their service somewhere on the site.
Availability should also be a concern. Just because a site shows that it stocks the medication you need, be it Tramadol or Viagra, doesn't mean it has them in stock at all times. Like a real store, online shops can run out of medication and have to place your order in the back, until their stocks are replenished. This can be a problem if the store doesn't inform you of this immediately, leaving you hanging and potentially facing side effects or unwanted symptoms because you missed a dose or two of your medication.